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BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 system-side impedance track ? fuel gauge with integrated ldo check for samples: BQ27520-G1 1 introduction ? battery fuel gauge based on patented 1.1 features impedance track ? technology 123 ? battery fuel gauge for 1-series li-ion C models the battery discharge curve for applications accurate time-to-empty predictions ? resides on system main board C automatically adjusts for battery aging, C works with embedded or removable battery self-discharge, and battery packs temperature/rate inefficiencies ? uses pack+ , pack C , and t battery terminals C low-value sense resistor (5 m ? to 20 m ? ) ? microcontroller peripheral provides: ? 400-khz i 2 c ? interface for connection to C accurate battery fuel gauging system microcontroller port C internal temperature sensor for battery ? in a 15-pin nanofree ? (csp) packaging temperature reporting C battery low interrupt warning 1.2 applications C battery insertion indicator ? smartphones C configurable level of state of charge (soc) ? pdas interrupts ? digital still and video cameras C state of health indicator C current data logging buffer ? handheld terminals C 64 bytes of non-volatile scratch-pad flash ? mp3 or multimedia players 1.3 description the texas instruments BQ27520-G1 system-side li-ion battery fuel gauge is a microcontroller peripheral that provides fuel gauging for single-cell li-ion battery packs. the device requires little system microcontroller firmware development. the BQ27520-G1 resides on the system s main board and manages an embedded battery (non-removable) or a removable battery pack. the BQ27520-G1 uses the patented impedance track ? algorithm for fuel gauging, and provides information such as remaining battery capacity (mah), state-of-charge (%), run-time to empty (min), battery voltage (mv), temperature ( c) and state of health (%). battery fuel gauging with the BQ27520-G1 requires only pack+ (p+), pack C (p C ), and thermistor (t) connections to a removable battery pack or embedded battery circuit. the csp option is a 15-ball package in the dimensions of 2,61 mm 1,96 mm with 0,5 mm lead pitch. it is ideal for space constrained applications. spacer spacer 1 please be aware that an important notice concerning availability, standard warranty, and use in critical applications of texas instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. 2 impedance track, nanofree are trademarks of texas instruments. 3 i 2 c is a trademark of nxp b.v. corp netherlands. production data information is current as of publication date. copyright ? 2011, texas instruments incorporated products conform to specifications per the terms of the texas instruments standard warranty. production processing does not necessarily include testing of all parameters.
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com typical application 2 introduction copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1 host system single cell li-lon battery pack pack- protection ic chg dsg temp sense soc_int current sense t pack+ voltage sense bat_gd low fets bq27520 power management controller vcc data ldo i2c battery ce
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 these devices have limited built-in esd protection. the leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the mos gates. 1 introduction ......................................... 1 4.4 access modes .................................. 23 1.1 features .......................................... 1 4.5 sealing/unsealing data flash ............. 23 1.2 applications ...................................... 1 4.6 data flash summary .......................... 24 1.3 description ....................................... 1 5 functional description ........................ 26 2 device information ................................ 4 5.1 fuel gauging ................................... 26 2.1 available options ............................... 4 5.2 impedance track ? variables .............. 27 5.3 detailed pin description .................... 29 2.2 thermal information .......................... 4 5.4 temperature measurement ................ 34 2.3 pin assignment .................................. 4 5.5 overtemperature indication .............. 34 3 electrical specifications ..................... 6 5.6 charging and charge-termination 3.1 absolute maximum ratings .................. 6 indication ........................................ 34 3.2 recommended operating conditions ..... 6 5.7 power modes ................................... 35 3.3 power-on reset ................................. 7 5.8 power control ................................ 36 3.4 2.5v ldo regulator ............................. 7 5.9 autocalibration ............................... 37 3.5 internal temperature sensor 6 application-specific information ......... 37 characteristics ................................ 7 6.1 battery profile storage and selection ...................................................... 37 3.6 high-frequency oscillator ................. 7 6.2 application-specific flow and control 3.7 low-frequency oscillator .................. 8 ...................................................... 38 3.8 integrating adc (coulomb counter) 7 communications characteristics ................................ 8 7.1 i 2 c interface 3.9 adc (temperature and cell measurement) characteristics ............ 8 7.2 i 2 c time out 3.10 data flash memory characteristics ..... 9 7.3 i 2 c command waiting time 3.11 i 2 c-compatible interface communication 7.4 i 2 c clock stretching timing characteristics ....................... 9 8 reference schematics 4 general description ............................ 10 8.1 schematic 4.1 data commands ................................ 11 8.2 package dimensions 4.2 data flash interface ........................ 21 revision history 4.3 manufacturer information blocks ...... 22 copyright ? 2011, texas instruments incorporated contents 3 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 2 device information 2.1 available options firmware tape and reel part number package (1) t a communication format version quantity bq27520yzfr-g1 3000 3.01 csp-15 C 40 c to 85 c i 2 c bq27520yzft-g1 250 (1) for the most current package and ordering information, see the package option addendum at the end of this document, or see the ti website at www.ti.com . 2.2 thermal information BQ27520-G1 thermal metric (1) units yzf(15 pins) ja junction-to-ambient thermal resistance 70 jctop junction-to-case (top) thermal resistance 17 jb junction-to-board thermal resistance 20 c/w jt junction-to-top characterization parameter 1 jb junction-to-board characterization parameter 18 jcbot junction-to-case (bottom) thermal resistance n/a (1) for more information about traditional and new thermal metrics, see the ic package thermal metrics application report, spra953 2.3 pin assignment 4 device information copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1 csp-15 (top view) a1 a2 a3 b1 b2 c1 c2 c3 d1 d2 d3 b3 a1 a2 a3 b1 b2 b3 c1 c2 c3 d1 d2 d3 csp-15 (bottom view) e 1 e 2 e 3 e 1 e 2 e 3
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 table 2-1. pin functions pin type (1) description name no. analog input pin connected to the internal coulomb counter where srp is nearest the pack C connection. connect to srp a1 ia 5-m ? to 20-m ? sense resistor. analog input pin connected to the internal coulomb counter where srn is nearest the vss connection. connect to srn b1 ia 5-m ? to 20-m ? sense resistor. v ss c1, c2 p device ground v cc d1 p regulator output and BQ27520-G1 power. decouple with 1 f ceramic capacitor to vss. regin e1 p regulator input. decouple with 0.1 f ceramic capacitor to vss. soc_int a2 i/o soc state interrupts output. generate a pulse under the conditions specified by table 5-6 . open drain output. battery-good indicator. active- low by default, though polarity can be configured through the [batg_pol] bit of bat_gd b2 o operation configuration . push-pull output. ce d2 i chip enable. internal ldo is disconnected from regin when driven low. bat e2 i cell-voltage measurement input. adc input. recommend 4.8v maximum for conversion accuracy. slave i 2 c serial communications clock input line for communication with system (master). use with 10k ? pull-up scl a3 i resistor (typical). slave i 2 c serial communications data line for communication with system (master). open-drain i/o. use with 10k ? sda b3 i/o pull-up resistor (typical). battery low output indicator. active high by default, though polarity can be configured through the [batl_pol] bit of bat_low c3 o operation configuration . push-pull output. ts d3 ia pack thermistor voltage sense (use 103at-type thermistor). adc input. battery-insertion detection input. power pin for pack thermistor network. thermistor-multiplexer control pin. use with bi/tout e3 i/o pull-up resistor > 1m ? (1.8 m ? typical). (1) i/o = digital input/output, ia = analog input, p = power connection copyright ? 2011, texas instruments incorporated device information 5 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 3 electrical specifications 3.1 absolute maximum ratings over operating free-air temperature range (unless otherwise noted) (1) parameter value unit v regin regulator input range C 0.3 to 5.5 v v cc supply voltage range C 0.3 to 2.75 v v iod open-drain i/o pins (sda, scl, soc_int) C 0.3 to 5.5 v v bat bat input pin C 0.3 to 5.5 v i input voltage range to all other pins (bi/tout, ts, srp, srn, bat_gd) C 0.3 to v cc + 0.3 v human-body model (hbm), bat pin 1.5 esd kv human-body model (hbm), all other pins 2 t a operating free-air temperature range C 40 to 85 c t f functional temperature range C 40 to 100 c t stg storage temperature range C 65 to 150 c (1) stresses beyond those listed under " absolute maximum ratings " may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under " recommended operating conditions " is not implied. exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 3.2 recommended operating conditions t a = 25 c and v regin = v bat = 3.6v (unless otherwise noted) parameter test conditions min typ max unit no operating restrictions 2.7 4.5 v regin supply voltage v no flash writes 2.45 2.7 external input capacitor for internal ldo between c regin 0.1 f nominal capacitor values specified. regin and v ss recommend a 5% ceramic x5r type external output capacitor for internal ldo between capacitor located close to the device. c ldo25 0.47 1 f v cc and v ss fuel gauge in normal mode. i cc normal operating-mode current (1) 118 a i load > sleep current fuel gauge in sleep+ mode. i slp+ sleep+ operating mode current (1) 62 a i load < sleep current fuel gauge in sleep mode. i slp low-power storage-mode current (1) 23 a i load < sleep current fuel gauge in hibernate mode. i hib hibernate operating-mode current (1) 8 a i load < hibernate current output voltage, low (scl, sda, soc_int, v ol i ol = 3 ma 0.4 v bat_low) v oh(pp) output voltage, high (bat_low, bat_gd) i oh = C 1 ma v cc C 0.5 v v oh(od) output voltage, high (sda, scl, soc_int) external pullup resistor connected to v cc v cc C 0.5 v input voltage, low (sda, scl) C 0.3 0.6 v il input voltage, low (bi/tout) bat insert check mode active C 0.3 0.6 v input voltage, high (sda, scl) 1.2 6 v ih(od) v cc + input voltage, high (bi/tout) bat insert check mode active 1.2 0.3 v a1 input voltage range (ts) v ss C 0.125 2 v v a2 input voltage range (bat) v ss C 0.125 5 v v a3 input voltage range (srp, srn) v ss C 0.125 0.125 v i lkg input leakage current (i/o pins) 0.3 a t pucd power-up communication delay 250 ms (1) specified by design. not production tested. 6 electrical specifications copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 3.3 power-on reset t a = C 40 c to 85 c, typical values at t a = 25 c and v regin = 3.6 v (unless otherwise noted) parameter test conditions min typ max unit v it+ positive-going battery voltage input at v cc 2.09 2.20 2.31 v v hys power-on reset hysteresis 45 115 185 mv 3.4 2.5v ldo regulator t a = 25 c, c ldo25 = 1 f, v regin = 3.6v (unless otherwise noted) parameter test condition min nom max unit 2.5 v ldo regulator (1) 2.7v v regin 4.5v, i out 16ma t a = C 40 c to 85 c 2.4 2.5 2.54 v v reg25 regulator output voltage 2.45v v regin < 2.7v (low battery), t a = C 40 c to 85 c 2.4 v i out 3ma ce high-level input v ih(ce) 2.65 voltage vregin = 2.7 to 4.5v t a = C 40 c to 85 c v ce low-level input v il(ce) 0.8 voltage 2.7v, i out 16ma t a = C 40 c to 85 c 325 v do regulator dropout voltage mv 2.45v, i out 3ma t a = C 40 c to 85 c 50 regulator output change v regtemp v regin = 3.6v, i out = 16ma t a = C 40 c to 85 c 0.5% with temperature v regline line regulation 2.7v v regin 4.5v, i out = 16ma 18 40 mv 0.2ma i out 3ma, v regin = 2.45 v 34 40 v regload load regulation mv 3ma i out 16ma, v regin = 2.7 v 31 i short (2) short circuit current limit v reg25 = 0v t a = C 40 c to 85 c 250 ma (1) ldo output current, i out , is the sum of internal and external load currents. (2) assured by design. not production tested. 3.5 internal temperature sensor characteristics t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit g temp temperature sensor voltage gain C 2 mv/ c 3.6 high-frequency oscillator t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit f osc operating frequency 2.097 mhz t a = 0 c to 60 c C 2% 0.38% 2% f eio frequency error (1) (2) t a = C 20 c to 70 c C 3% 0.38% 3% t a = C 40 c to 85 c C 4.5% 0.38% 4.5% t sxo start-up time (3) 2.5 5 ms (1) the frequency error is measured from 2.097 mhz. (2) the frequency drift is included and measured from the trimmed frequency at v cc = 2.5 v, t a = 25 c. (3) the start-up time is defined as the time it takes for the oscillator output frequency to be within 3% of typical oscillator frequency. copyright ? 2011, texas instruments incorporated electrical specifications 7 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 3.7 low-frequency oscillator t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit f losc operating frequency 32.768 khz t a = 0 c to 60 c C 1.5% 0.25% 1.5% f leio frequency error (1) (2) t a = C 20 c to 70 c C 2.5% 0.25% 2.5% t a = C 40 c to 85 c C 4% 0.25% 4% t lsxo start-up time (3) 500 s (1) the frequency drift is included and measured from the trimmed frequency at v cc = 2.5 v, t a = 25 c. (2) the frequency error is measured from 32.768 khz. (3) the start-up time is defined as the time it takes for the oscillator output frequency to be within 3% of typical oscillator frequency. 3.8 integrating adc (coulomb counter) characteristics t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit v sr input voltage range, v (srn) and v (srp) v sr = v (srn) C v (srp) C 0.125 0.125 v t sr_conv conversion time single conversion 1 s resolution 14 15 bits v os(sr) input offset 10 v inl integral nonlinearity error 0.007 0.034 % fsr z in(sr) effective input resistance (1) 2.5 m ? i lkg(sr) input leakage current (1) 0.3 a (1) specified by design. not tested in production. 3.9 adc (temperature and cell measurement) characteristics t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit v in(adc) input voltage range 0.05 1 v t adc_conv conversion time 125 ms resolution 14 15 bits v os(adc) input offset 1 mv z adc1 effective input resistance (ts) (1) 8 m ? BQ27520-G1 not measuring cell voltage 8 m ? z adc2 effective input resistance (bat) (1) BQ27520-G1 measuring cell voltage 100 k ? i lkg(adc) input leakage current (1) 0.3 a (1) specified by design. not tested in production. 8 electrical specifications copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 3.10 data flash memory characteristics t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit t dr data retention (1) 10 years flash-programming write cycles (1) 20,000 cycles t wordprog word programming time (1) 2 ms i ccprog flash-write supply current (1) 5 10 ma t dferase data flash master erase time (1) 200 ms t iferase instruction flash master erase time (1) 200 ms t pgerase flash page erase time (1) 20 ms (1) specified by design. not production tested 3.11 i 2 c-compatible interface communication timing characteristics t a = C 40 c to 85 c, 2.4 v < v cc < 2.6 v; typical values at t a = 25 c and v cc = 2.5 v (unless otherwise noted) parameter test conditions min typ max unit t r scl/sda rise time 300 ns t f scl/sda fall time 300 ns t w(h) scl pulse duration (high) 600 ns t w(l) scl pulse duration (low) 1.3 s t su(sta) setup for repeated start 600 ns t d(sta) start to first falling edge of scl 600 ns t su(dat) data setup time 100 ns t h(dat) data hold time 0 ns t su(stop) setup time for stop 600 ns t (buf) bus free time between stop and start 66 s t d(clkstr) clock stretch delay fullsleep mode, all i2c packets 150 s normal mode, only i2c packets 144 ms directed to fuel gauge. maximum only occurs during data flash updates. f scl clock frequency 400 khz figure 3-1. i 2 c-compatible interface timing diagrams copyright ? 2011, texas instruments incorporated electrical specifications 9 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 4 general description the BQ27520-G1 accurately predicts the battery capacity and other operational characteristics of a single li-based rechargeable cell. it can be interrogated by a system processor to provide cell information, such as time-to-empty (tte), time-to-full (ttf) and state-of-charge (soc) as well as soc interrupt signal to the host. information is accessed through a series of commands, called standard commands . further capabilities are provided by the additional extended commands set. both sets of commands, indicated by the general format command( ) , are used to read and write information contained within the device control and status registers, as well as its data flash locations. commands are sent from system to gauge using the BQ27520-G1 s i 2 c serial communications engine, and can be executed during application development, pack manufacture, or end-equipment operation. cell information is stored in the device in non-volatile flash memory. many of these data flash locations are accessible during application development. they cannot, generally, be accessed directly during end-equipment operation. access to these locations is achieved by either use of the BQ27520-G1 s companion evaluation software, through individual commands, or through a sequence of data-flash-access commands. to access a desired data flash location, the correct data flash subclass and offset must be known. the BQ27520-G1 provides two 32-byte user-programmable data flash memory blocks: manufacturer info block a and manufacturer info block b . this data space is accessed through a data flash interface. for specifics on accessing the data flash, manufacturer information blocks . the key to the BQ27520-G1 s high-accuracy gas gauging prediction is texas instrument s proprietary impedance track ? algorithm. this algorithm uses cell measurements, characteristics, and properties to create state-of-charge predictions that can achieve less than 1% error across a wide variety of operating conditions and over the lifetime of the battery. the device measures charge/discharge activity by monitoring the voltage across a small-value series sense resistor (5 m ? to 20 m ? typ.) located between the system s vss and the battery s pack- terminal. when a cell is attached to the device, cell impedance is computed, based on cell current, cell open-circuit voltage (ocv), and cell voltage under loading conditions. the device external temperature sensing is optimized with the use of a high accuracy negative temperature coefficient (ntc) thermistor with r25 = 10.0k ? 1%. b25/85 = 3435k 1% (such as semitec ntc 103at). the BQ27520-G1 can also be configured to use its internal temperature sensor. when an external thermistor is used, a 18.2k pull up resistor between bt/tout and ts pins is also required. the BQ27520-G1 uses temperature to monitor the battery-pack environment, which is used for fuel gauging and cell protection functionality. to minimize power consumption, the device has different power modes: normal, sleep, sleep+, hibernate, and bat insert check. the BQ27520-G1 passes automatically between these modes, depending upon the occurrence of specific events, though a system processor can initiate some of these modes directly. more details can be found in power modes . note formatting conventions in this document: commands: italics with parentheses and no breaking spaces, e.g., remainingcapacity( ) data flash: italics , bold , and breaking spaces , e.g., design capacity register bits and flags: brackets and italics , e.g., [tda] data flash bits: brackets, italics and bold , e.g., [led1] modes and states: all capitals, e.g., unsealed mode. 10 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.1 data commands 4.1.1 standard data commands the BQ27520-G1 uses a series of 2-byte standard commands to enable system reading and writing of battery information. each standard command has an associated command-code pair, as indicated in table 4-1 . because each command consists of two bytes of data, two consecutive i 2 c transmissions must be executed both to initiate the command function, and to read or write the corresponding two bytes of data. additional options for transferring data, such as spooling, are described in section of communication . standard commands are accessible in normal operation. read/write permissions depend on the active access mode, sealed or unsealed (for details on the sealed and unsealed states, see section 4.4 , access modes.) table 4-1. standard commands sealed unsealed name command code units access access control( ) cntl 0x00 / 0x01 n/a r/w r/w atrate( ) ar 0x02 / 0x03 ma r/w r/w atratetimetoempty( ) artte 0x04 / 0x05 minutes r r/w temperature( ) temp 0x06 / 0x07 0.1 k r/w r/w voltage( ) volt 0x08 / 0x09 mv r r/w flags( ) flags 0x0a / 0x0b n/a r r/w nominalavailablecapacity( ) nac 0x0c / 0x0d mah r r/w fullavailablecapacity( ) fac 0x0e / 0x0f mah r r/w remainingcapacity( ) rm 0x10 / 0x11 mah r r/w fullchargecapacity( ) fcc 0x12 / 0x13 mah r r/w averagecurrent( ) ai 0x14 / 0x15 ma r r/w timetoempty( ) tte 0x16 / 0x17 minutes r r/w timetofull( ) ttf 0x18 / 0x19 minutes r r/w standbycurrent( ) si 0x1a / 0x1b ma r r/w standbytimetoempty( ) stte 0x1c / 0x1d minutes r r/w maxloadcurrent( ) mli 0x1e / 0x1f ma r r/w maxloadtimetoempty( ) mltte 0x20 / 0x21 minutes r r/w availableenergy( ) ae 0x22 / 0x23 mwh r r/w averagepower( ) ap 0x24 / 0x25 mw r r/w tteatconstantpower( ) ttecp 0x26 / 0x27 minutes r r/w stateofhealth() soh 0x28 / 0x29 % / num r r/w stateofcharge( ) soc 0x2c / 0x2d % r r/w normalizedimpedancecal( ) nic 0x2e / 0x2f mohm r r/w instantaneouscurrentreading( ) icr 0x30 / 0x31 ma r r/w datalogindex( ) dli 0x32 / 0x33 n/a r r datalogbuffer( ) dlb 0x34 / 0x35 ma r r copyright ? 2011, texas instruments incorporated general description 11 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 4.1.1.1 control( ) : 0x00/0x01 issuing a control( ) command requires a subsequent 2-byte subcommand. these additional bytes specify the particular control function desired. the control( ) command allows the system to control specific features of the BQ27520-G1 during normal operation and additional features when the device is in different access modes, as described in table 4-2 . table 4-2. control( ) subcommands cntl sealed cntl function description data access control_status 0x0000 yes reports the status of df checksum, hibernate, it, etc. device_type 0x0001 yes reports the device type (eg: BQ27520-G1) fw_version 0x0002 yes reports the firmware version on the device type hw_version 0x0003 yes reports the hardware version of the device type df_checksum 0x0004 no enables a data flash checksum to be generated and reports on a read prev_macwrite 0x0007 yes returns previous mac subcommand code chem_id 0x0008 yes reports the chemical identifier of the impedance track ? configuration board_offset 0x0009 no forces the device to measure and store the board offset cc_int_offset 0x000a no forces the device to measure the internal cc offset write_cc_offset 0x000b no forces the device to store the internal cc offset ocv_cmd 0x000c yes request the gauge to take a ocv measurement bat_insert 0x000d yes forces the bat_det bit set when the [bie] bit is 0 bat_remove 0x000e yes forces the bat_det bit clear when the [bie] bit is 0 set_hibernate 0x0011 yes forces control_status [hibernate] to 1 clear_hibernate 0x0012 yes forces control_status [hibernate] to 0 set_sleep+ 0x0013 yes forces control_status [snooze] to 1 clear_sleep+ 0x0014 yes forces control_status [snooze] to 0 factory_restore 0x0015 no forces a factory restore of learned resistance and qmax to defaults enable_dlog 0x0018 yes commands the device to start coulomb counter data logging mode. disable_dlog 0x0019 yes commands the device to stop data logging mode. sealed 0x0020 no places the BQ27520-G1 in sealed access mode it_enable 0x0021 no enables the impedance track ? algorithm it_disable 0x0023 no disables the impedance track ? algorithm cal_mode 0x0040 no places the BQ27520-G1 in calibration mode reset 0x0041 no forces a full reset of the BQ27520-G1 12 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.1.1.1.1 control_status: 0x0000 instructs the fuel gauge to return status information to control addresses 0x00/0x01. the status word includes the following information. table 4-3. control_status bit definitions bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 high byte dlogen fas ss csv cca bca ocvcmdcomp ocvfail low byte initcomp hibernate snooze sleep ldmd rup_dis vok qen dlogen = status biting the BQ27520-G1 is in current data logging mode. true when set. fas = status bit indicating the BQ27520-G1 is in full access sealed state. active when set. ss = status bit indicating the BQ27520-G1 is in sealed state. active when set. csv = status bit indicating a valid data flash checksum has been generated. active when set. cca = status bit indicating the BQ27520-G1 coulomb counter calibration routine is active. the cca routine will take place approximately 1 minute after the initialization. active when set. bca = status bit indicating the BQ27520-G1 board calibration routine is active. active when set. ocvcmdcomp = status bit indicating the BQ27520-G1 has executed the ocv command. this bit can only be set with battery s presence. true when set. ocvfail = status bit indicating BQ27520-G1 ocv reading is failed due to the current. this bit can only be set with battery s presence. true when set. initcomp = initialization completion bit indicating the initialization completed. this bit can only be set with battery s presence. true when set. hibernate = status bit indicating a request for entry into hibernate from sleep mode. true when set. default is 0. snooze = status bit indicating the BQ27520-G1 sleep+ mode is enabled. true when set. sleep = status bit indicating the BQ27520-G1 is in sleep mode. true when set. ldmd = status bit indicating the BQ27520-G1 impedance track ? algorithm is using constant-power mode. true when set. default is 0 (constant-current mode). rup_dis = status bit indicating the BQ27520-G1 ra table updates are disabled. updates disabled when set. vok = status bit indicating the BQ27520-G1 voltages are okay for qmax. true when set. qen = status bit indicating the BQ27520-G1 qmax updates enabled. true when set. 4.1.1.1.2 device_type: 0x0001 instructs the fuel gauge to return the device type to addresses 0x00/0x01. 4.1.1.1.3 fw_version: 0x0002 instructs the fuel gauge to return the firmware version to addresses 0x00/0x01. 4.1.1.1.4 hw_version: 0x0003 instructs the fuel gauge to return the hardware version to addresses 0x00/0x01. 4.1.1.1.5 df_checksum: 0x0004 instructs the fuel gauge to compute the checksum of the data flash memory. the checksum value is written and returned to addresses 0x00/0x01 (unsealed mode only). the checksum will not be calculated in sealed mode; however, the checksum value can still be read. 4.1.1.1.6 prev_macwrite: 0x0007 instructs the fuel gauge to return the previous subcommand written to addresses 0x00/0x01. 4.1.1.1.7 chem_id: 0x0008 instructs the fuel gauge to return the chemical identifier for the impedance track ? configuration to addresses 0x00/0x01. 4.1.1.1.8 board_offset: 0x0009 instructs the fuel gauge to compute the coulomb counter offset with internal short and then without internal short applied across the sensing resistor (sr) inputs. the difference between the two measurements is copyright ? 2011, texas instruments incorporated general description 13 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com the board offset. after a delay of approximately 32 seconds, this offset value is returned to addresses 0x00/0x01 and written to data flash. the control status [bca] is also set. the user must prevent any charge or discharge current from flowing during the process. this function is only available when the fuel gauge is unsealed. when sealed, this command only reads back the board-offset value stored in data flash. 4.1.1.1.9 cc_int_offset: 0x000a control data of 0x000a instructs the fuel gauge to compute the coulomb counter offset with internal short applied across the sr inputs. the offset value is returned to addresses 0x00/0x01, after a delay of approximately 16 seconds. this function is only available when the fuel gauge is unsealed. when sealed, this command only reads back the cc_int_offset value stored in data flash. 4.1.1.1.10 write_offset: 0x000b control data of 0x000b causes the fuel gauge to write the coulomb counter offset to data flash. 4.1.1.1.11 ocv cmd: 0x000c this command is to request the gauge to take a ocv reading. this command can only be issued after the [inicomp] has been set, indicating the initialization has been completed. the ocv measurement take place at the beginning of the next repeated 1s firmware synchronization clock. during the same time period, the soc_int will pulse. the host should use this signal to reduce the load current below the c/20 in 8ms for a valid ocv reading. the ocv command [ocvfail] bit will be set if the ocv_cmd is issued when [chg_inh] is set. 4.1.1.1.12 bat_insert: 0x000d this command is to force the bat_det bit to be set when the battery insertion detection is disabled. when the bie is set to 0, the battery insertion detection is disabled. the gauge relies on the host to inform the battery insertion with this command to set the bat_det bit. 4.1.1.1.13 bat_remove: 0x000e this command is to force the bat_det bit to be clear when the battery insertion detection is disabled. when the bie is set to 0, the battery insertion detection is disabled. the gauge relies on the host to inform the battery removal with this command to clear the bat_det bit. 4.1.1.1.14 set_hibernate: 0x0011 instructs the fuel gauge to force the control_status [hibernate] bit to 1. this will allow the gauge to enter the hibernate power mode after the transition to sleep power state is detected. the [hibernate] bit is automatically cleared upon exiting from hibernate mode. 4.1.1.1.15 clear_hibernate: 0x0012 instructs the fuel gauge to force the control_status [hibernate] bit to 0. this prevents the gauge from entering the hibernate power mode after the transition to the sleep power state is detected. it can also be used to force the gauge out of hibernate mode. 4.1.1.1.16 set_sleep+ mode: 0x0013 instructs the fuel gauge to set the control_status [snooze] bit to 1. this will enable the sleep+ mode. the gauge will enter sleep+ power mode after the transition conditions are meet. 4.1.1.1.17 clear_sleep+ mode: 0x0014 instructs the fuel gauge to set the control_status [snooze] bit to 0. this will disable the sleep+ mode. the gauge will exit from the sleep+ power mode after the snooze bit is cleared. 14 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.1.1.1.18 factory restore: 0x0015 instructs the fuel gauge to reset learned resistance tables and qmax values to the default values. soc_int is asserted while the restore is in progress. this command is only available when the fuel gauge is unsealed. 4.1.1.1.19 enable_dlog: 0x0018 commands the fuel gauge to set the control_status[dlogen] bit to 1, clear the data fifo, and begin recording coulomb counter data logging. while in data logging mode, the device will not enter sleep mode. 4.1.1.1.20 disable_dlog: 0x0019 commands the fuel gauge to clear the control_status[dlogen] bit to 0 and stop recording coulomb counter data. the previous data stored in the fifo is not cleared. 4.1.1.1.21 sealed: 0x0020 instructs the fuel gauge to transition from the unsealed state to the sealed state. the fuel gauge must always be set to the sealed state for use in end equipment. 4.1.1.1.22 it_enable: 0x0021 this command forces the fuel gauge to begin the impedance track ? algorithm, sets the it enable to 0x01 and causes the [vok] and [qen] flags to be set in the control_status register. [vok] is cleared if the voltages are not suitable for a qmax update. this command is only available when the fuel gauge is unsealed. 4.1.1.1.23 it_disable: 0x0023 this command disables the fuel gauge the impedance track ? algorithm, clears the it enable to 0x00 and causes the [qen] flags to be cleared in the control_status register. this command is only available when the fuel gauge is unsealed. 4.1.1.1.24 cal_mode: 0x0040 this command instructs the fuel gauge to enter calibration mode. this command is only available when the fuel gauge is unsealed. 4.1.1.1.25 reset: 0x0041 this command instructs the fuel gauge to perform a full reset. this command is only available when the fuel gauge is unsealed. 4.1.1.2 atrate( ) : 0x02/0x03 the atrate( ) read-/write-word function is the first half of a two-function command set used to set the atrate value used in calculations made by the atratetimetoempty( ) function. the atrate( ) units are in ma. the atrate( ) value is a signed integer, with negative values interpreted as a discharge current value. the atratetimetoempty( ) function returns the predicted operating time at the atrate value of discharge. the default value for atrate( ) is zero and forces atratetimetoempty( ) to return 65,535. both the atrate( ) and atratetimetoempty( ) commands must only be used in normal mode. 4.1.1.3 atratetimetoempty( ) : 0x04/0x05 this read-word function returns an unsigned integer value of the predicted remaining operating time if the copyright ? 2011, texas instruments incorporated general description 15 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com battery is discharged at the atrate( ) value in minutes with a range of 0 to 65,534. a value of 65,535 indicates atrate( ) = 0. the fuel gauge updates atratetimetoempty( ) within 1 s after the system sets the atrate( ) value. the fuel gauge automatically updates atratetimetoempty( ) based on the atrate( ) value every 1 s. both the atrate( ) and atratetimetoempty( ) commands must only be used in normal mode. 4.1.1.4 temperature( ) : 0x06/0x07 this read-/write-word function returns an unsigned integer value of the temperature in units of 0.1 k measured by the fuel gauge. when [temps] bit = 0, a read command will return the internal temperature sensor value. when [temps] bit = 1, a read command will return the external thermistor measurement value. 4.1.1.5 voltage( ) : 0x08/0x09 this read-word function returns an unsigned integer value of the measured cell-pack voltage in mv with a range of 0 to 6000 mv. 4.1.1.6 flags( ) : 0x0a/0x0b this read-word function returns the contents of the fuel-gauge status register, depicting the current operating status. table 4-4. flags bit definitions bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 high byte otc otd C C chg_inh xchg fc chg low byte C C ocv_gd wait_id bat_det soc1 sysdown dsg otc = overtemperature in charge condition is detected. true when set. otd = overtemperature in discharge condition is detected. true when set. chg_inh = charge inhibit: unable to begin charging (temperature outside the range [charge inhibit temp low, charge inhibit temp high] ). true when set. xchg = charge suspend alert (temperature outside the range [suspend temperature low, suspend temperature high] ). true when set. fc = full-charged condition reached. set when charge termination condition is met. (rmfcc=1; set fc_set % = -1% when rmfcc = 0). true when set chg = (fast) charging allowed. true when set. ocv_gd = good ocv measurement taken. true when set. wait_id = waiting to identify inserted battery. true when set. bat_det = battery detected. true when set. soc1 = state-of-charge threshold 1 ( soc1 set ) reached. the flag is enabled when bl_int bit in operation configuration b is set. true when set. sysdown = systemdown bit indicating the system shut down. true when set dsg = discharging detected. true when set. 4.1.1.7 nominalavailablecapacity( ) : 0x0c/0x0d this read-only command pair returns the uncompensated (less than c/20 load) battery capacity remaining. units are mah. 4.1.1.8 fullavailablecapacity( ) : 0x0e/0x0f this read-only command pair returns the uncompensated (less than c/20 load) capacity of the battery when fully charged. units are mah. fullavailablecapacity( ) is updated at regular intervals, as specified by the it algorithm. 4.1.1.9 remainingcapacity( ) : 0x10/0x11 this read-only command pair returns the compensated battery capacity remaining. units are mah. 4.1.1.10 fullchargecapacity( ) : 0x12/13 this read-only command pair returns the compensated capacity of the battery when fully charged. units are mah. fullchargecapacity( ) is updated at regular intervals, as specified by the it algorithm. 16 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.1.1.11 averagecurrent( ) : 0x14/0x15 this read-only command pair returns a signed integer value that is the average current flow through the sense resistor. it is updated every 1 second. units are ma. 4.1.1.12 timetoempty( ) : 0x16/0x17 this read-only function returns an unsigned integer value of the predicted remaining battery life at the present rate of discharge, in minutes. a value of 65,535 indicates battery is not being discharged. 4.1.1.13 timetofull( ) : 0x18/0x19 this read-only function returns an unsigned integer value of predicted remaining time until the battery reaches full charge, in minutes, based upon averagecurrent( ) . the computation accounts for the taper current time extension from the linear ttf computation based on a fixed averagecurrent( ) rate of charge accumulation. a value of 65,535 indicates the battery is not being charged. 4.1.1.14 standbycurrent( ) : 0x1a/0x1b this read-only function returns a signed integer value of the measured standby current through the sense resistor. the standbycurrent( ) is an adaptive measurement. initially it reports the standby current programmed in initial standby , and after spending several seconds in standby, reports the measured standby current. the register value is updated every 1 second when the measured current is above the deadband and is less than or equal to 2 initial standby . the first and last values that meet this criteria are not averaged in, since they may not be stable values. to approximate a 1 minute time constant, each new standbycurrent( ) value is computed by taking approximate 93% weight of the last standby current and approximate 7% of the current measured average current. 4.1.1.15 standbytimetoempty( ) : 0x1c/0x1d this read-only function returns an unsigned integer value of the predicted remaining battery life at the standby rate of discharge, in minutes. the computation uses nominal available capacity (nac), the uncompensated remaining capacity, for this computation. a value of 65,535 indicates battery is not being discharged. 4.1.1.16 maxloadcurrent( ) : 0x1e/0x1f this read-only function returns a signed integer value, in units of ma, of the maximum load conditions. the maxloadcurrent( ) is an adaptive measurement which is initially reported as the maximum load current programmed in initial max load current . if the measured current is ever greater than initial max load current , then maxloadcurrent( ) updates to the new current. maxloadcurrent( ) is reduced to the average of the previous value and initial max load current whenever the battery is charged to full after a previous discharge to an soc less than 50%. this prevents the reported value from maintaining an unusually high value. 4.1.1.17 maxloadtimetoempty( ) : 0x20/0x21 this read-only function returns an unsigned integer value of the predicted remaining battery life at the maximum load current discharge rate, in minutes. a value of 65,535 indicates that the battery is not being discharged. 4.1.1.18 availableenergy( ) : 0x22/0x23 this read-only function returns an unsigned integer value of the predicted charge or energy remaining in the battery. the value is reported in units of mwh. copyright ? 2011, texas instruments incorporated general description 17 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 4.1.1.19 averagepower( ) : 0x24/0x25 this read-only function returns an signed integer value of the average power during battery charging and discharging. it is negative during discharge and positive during charge. a value of 0 indicates that the battery is not being discharged. the value is reported in units of mw. 4.1.1.20 timetoemptyatconstantpower( ) : 0x26/0x27 this read-only function returns an unsigned integer value of the predicted remaining operating time if the battery is discharged at the averagepower( ) value in minutes. a value of 65,535 indicates averagepower( ) = 0. the fuel gauge automatically updates timetoemptyatcontantpower( ) based on the averagepower( ) value every 1 s. 4.1.1.21 stateofhealth( ) : 0x28/0x29 0x28 soh percentage: this read-only function returns an unsigned integer value, expressed as a percentage of the ration of predicted fcc(25 c, soh loadi) over the designcapacity() . the fcc(25 c, soh loadi) is the calculated full charge capacity at 25 c and the soh loadi which is specified in the data flash. the range of the returned soh percentage is 0x00 to 0x64, indicating 0 to 100% correspondingly. 0x29 soh status: this read-only function returns an unsigned integer value, indicating the status of the soh percentage. the meanings of the returned value are: ? 0x00: soh not valid (initialization) ? 0x01: instant soh value ready ? 0x02: initial soh value ready C calculation based on uncompensated qmax C updated at first grid point update after cell insertion ? 0x03: soh value ready C utilize the updated qmax update C calculation based on compensated qmax C updated after complete charge and relax is complete ? 0x04-0xff: reserved 4.1.1.22 stateofcharge( ) : 0x2c/0x2d this read-only function returns an unsigned integer value of the predicted remaining battery capacity expressed as a percentage of fullchargecapacity( ) , with a range of 0 to 100%. 4.1.1.23 normalizedimpedancecal( ) : 0x2e/0x2f this read-only function returns an unsigned integer value of the calculated normalized impedance to 0 c at the current depth of discharge, with the unit of m ? . 4.1.1.24 instantaneouscurrentreading( ): 0x30/0x31 this read-only function returns a signed integer value that is the instantaneous current flow through the sense resistor. the conversion time is 125ms. it is updated every 1 second. units are ma. 4.1.1.25 datalogindex( ): 0x32/0x33 in data logging mode, this read-only register returns an unsigned integer that increments for every new coulomb counter sample placed in the data fifo and decrements for each sample read by the host from datalogbuffer(). the index saturates at 30 counts to prevent rollover of the fifo and subsequent data samples are discarded. data logging is controlled by the enable_dlog and disable_dlog subcommands while status is provided by the control_status[dlogen] bit. 18 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.1.1.26 datalogbuffer( ): 0x34/0x35 in data logging mode, this read-only register returns a 16-bit signed coulomb counter value in ma. access to data is provided by a 30 sample fifo with the number of samples available from datalogindex(). if the fifo is empty, this value returned is 0x7fff. 4.1.2 extended data commands extended commands offer additional functionality beyond the standard set of commands. they are used in the same manner; however, unlike standard commands, extended commands are not limited to 2-byte words. the number of commands bytes for a given extended command ranges in size from single to multiple bytes, as specified in table 4-5 . table 4-5. extended data commands command sealed unsealed name units code access (1) (2) access (1) (2) reserved rsvd 0x34...0x3b n/a r r designcapacity( ) dcap 0x3c / 0x3d mah r r dataflashclass( ) (2) dfcls 0x3e n/a n/a r/w dataflashblock( ) (2) dfblk 0x3f n/a r/w r/w blockdata( ) dfd 0x40 0x5f n/a r r/w blockdatachecksum( ) dfdcks 0x60 n/a r/w r/w blockdatacontrol( ) dfdcntl 0x61 n/a n/a r/w devicenamelength( ) dnamelen 0x62 n/a r r devicename( ) dname 0x63...0x69 n/a r r applicationstatus( ) appstat 0x6a n/a r r reserved rsvd 0x6b...0x7f n/a r r (1) sealed and unsealed states are entered via commands to control() 0x00/0x01. (2) in sealed mode, data flash cannot be accessed through commands 0x3e and 0x3f. 4.1.2.1 designcapacity( ) : 0x3c/0x3d sealed and unsealed access: this command returns the value is stored in design capacity and is expressed in mah. this is intended to be the theoretical or nominal capacity of a new pack, but has no bearing on the operation of the fuel gauge functionality. 4.1.2.2 dataflashclass( ) : 0x3e unsealed access: this command sets the data flash class to be accessed. the class to be accessed must be entered in hexadecimal. sealed access: this command is not available in sealed mode. copyright ? 2011, texas instruments incorporated general description 19 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 4.1.2.3 dataflashblock( ) : 0x3f unsealed access: this command sets the data flash block to be accessed. when 0x00 is written to blockdatacontrol( ) , dataflashblock( ) holds the block number of the data flash to be read or written. example: writing a 0x00 to dataflashblock( ) specifies access to the first 32-byte block, a 0x01 specifies access to the second 32-byte block, and so on. sealed access: this command directs which data flash block is accessed by the blockdata( ) command. writing a 0x01 or 0x02 instructs the blockdata( ) command to transfer manufacturer info block a or b , respectively. all other dataflashblock( ) values are reserved. 4.1.2.4 blockdata( ) : 0x40 0x5f unsealed access: this data block is the remainder of the 32 byte data block when accessing data flash. sealed access: this data block is the remainder of the 32 byte data block when accessing manufacturer block info a or b . 4.1.2.5 blockdatachecksum( ) : 0x60 unsealed access: this byte contains the checksum on the 32 bytes of block data read or written to data flash. the least-significant byte of the sum of the data bytes written must be complemented ([255 C x ], for x the least-significant byte) before being written to 0x60. sealed access: this byte contains the checksum for the 32 bytes of block data written to manufacturer info block a or b . the least-significant byte of the sum of the data bytes written must be complemented ([255 C x ], for x the least-significant byte) before being written to 0x60. 4.1.2.6 blockdatacontrol( ) : 0x61 unsealed access: this command is used to control data flash access mode. writing 0x00 to this command enables blockdata( ) to access general data flash. writing a 0x01 to this command enables sealed mode operation of dataflashblock( ) . sealed access: this command is not available in sealed mode. 4.1.2.7 devicenamelength( ) : 0x62 unsealed and sealed access: this byte contains the length of the device name . 4.1.2.8 devicename( ) : 0x63 0x69 unsealed and sealed access: this block contains the device name that is programmed in device name . 4.1.2.9 applicationstatus( ) : 0x6a this byte function allows the system to read the BQ27520-G1 application status data flash location. see table 6-1 for specific bit definitions. 4.1.2.10 reserved 0x6b C 0x7f 20 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.2 data flash interface 4.2.1 accessing the data flash the BQ27520-G1 data flash is a non-volatile memory that contains BQ27520-G1 initialization, default, cell status, calibration, configuration, and user information. the data flash can be accessed in several different ways, depending on what mode the BQ27520-G1 is operating in and what data is being accessed. commonly accessed data flash memory locations, frequently read by a system, are conveniently accessed through specific instructions, already described in section 4.1 , data commands . these commands are available when the BQ27520-G1 is either in unsealed or sealed modes. most data flash locations, however, are only accessible in unsealed mode by use of the BQ27520-G1 evaluation software or by data flash block transfers. these locations should be optimized and/or fixed during the development and manufacture processes. they become part of a golden image file and can then be written to multiple battery packs. once established, the values generally remain unchanged during end-equipment operation. to access data flash locations individually, the block containing the desired data flash location(s) must be transferred to the command register locations, where they can be read to the system or changed directly. this is accomplished by sending the set-up command blockdatacontrol( ) (0x61) with data 0x00. up to 32 bytes of data can be read directly from the blockdata( ) (0x40 0x5f), externally altered, then rewritten to the blockdata( ) command space. alternatively, specific locations can be read, altered, and rewritten if their corresponding offsets are used to index into the blockdata( ) command space. finally, the data residing in the command space is transferred to data flash, once the correct checksum for the whole block is written to blockdatachecksum( ) (0x60). occasionally, a data flash class will be larger than the 32-byte block size. in this case, the dataflashblock( ) command is used to designate which 32-byte block the desired locations reside in. the correct command address is then given by 0x40 + offset modulo 32. for example, to access terminate voltage in the gas gauging class, dataflashclass( ) is issued 80 (0x50) to set the class. because the offset is 50, it must reside in the second 32-byte block. hence, dataflashblock( ) is issued 0x01 to set the block offset, and the offset used to index into the blockdata( ) memory area is 0x40 + 50 modulo 32 = 0x40 + 18 = 0x40 + 0x12 = 0x52. reading and writing subclass data are block operations up to 32 bytes in length. if during a write the data length exceeds the maximum block size, then the data is ignored. none of the data written to memory are bounded by the BQ27520-G1 C the values are not rejected by the fuel gauge. writing an incorrect value may result in hardware failure due to firmware program interpretation of the invalid data. the written data is persistent, so a power-on reset does not resolve the fault. copyright ? 2011, texas instruments incorporated general description 21 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 4.3 manufacturer information blocks the BQ27520-G1 contains 64 bytes of user programmable data flash storage: manufacturer info block a , and manufacturer info block b . the method for accessing these memory locations is slightly different, depending on whether the device is in unsealed or sealed modes. when in unsealed mode and when and 0x00 has been written to blockdatacontrol( ) , accessing the manufacturer information blocks is identical to accessing general data flash locations. first, a dataflashclass( ) command is used to set the subclass, then a dataflashblock( ) command sets the offset for the first data flash address within the subclass. the blockdata( ) command codes contain the referenced data flash data. when writing the data flash, a checksum is expected to be received by blockdatachecksum( ) . only when the checksum is received and verified is the data actually written to data flash. as an example, the data flash location for manufacturer info block b is defined as having a subclass = 58 and an offset = 32 through 63 (32 byte block). the specification of class = system data is not needed to address manufacturer info block b , but is used instead for grouping purposes when viewing data flash info in the BQ27520-G1 evaluation software. when in sealed mode or when 0x01 blockdatacontrol( ) does not contain 0x00, data flash is no longer available in the manner used in unsealed mode. rather than issuing subclass information, a designated manufacturer information block is selected with the dataflashblock( ) command. issuing a 0x01 or 0x02 with this command causes the corresponding information block (a or b, respectively) to be transferred to the command space 0x40 0x5f for editing or reading by the system. upon successful writing of checksum information to blockdatachecksum( ) , the modified block is returned to data flash. note: manufacturer info block a is read-only when in sealed mode. 22 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 4.4 access modes the BQ27520-G1 provides three security modes (full access, unsealed, and sealed) that control data flash access permissions, according to table 4-6 . data flash refers to those data flash locations, specified in table 4-7 , that are accessible to the user. manufacture information refers to the two 32-byte blocks. table 4-6. data flash access security mode data flash manufacture information full access r/w r/w unsealed r/w r/w sealed none r(a); r/w(b) although full access and unsealed modes appear identical, only full access allows the BQ27520-G1 to write access-mode transition keys. 4.5 sealing/unsealing data flash the BQ27520-G1 implements a key-access scheme to transition between sealed, unsealed, and full-access modes. each transition requires that a unique set of two keys be sent to the BQ27520-G1 via the control( ) control command. the keys must be sent consecutively, with no other data being written to the control( ) register in between. note that to avoid conflict, the keys must be different from the codes presented in the cntl data column of table 4-2 subcommands. when in sealed mode, the control_status [ss] bit is set, but when the unseal keys are correctly received by the BQ27520-G1, the [ss] bit is cleared. when the full-access keys are correctly received, then the control_status [fas] bit is cleared. both the sets of keys for each level are 2 bytes each in length and are stored in data flash. the unseal key (stored at unseal key 0 and unseal key 1 ) and the full-access key (stored at full-access key 0 and full-access key 1 ) can only be updated when in full-access mode. the order of the keys is key 1 followed by key 0 . the order of the bytes entered through the control( ) command is the reverse of what is read from the part. for example, if the key 1 and key 0 of the unseal keys returns 0x1234 and 0x5678, then the control( ) should supply 0x3412 and 0x7856 to unseal the part. copyright ? 2011, texas instruments incorporated general description 23 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 4.6 data flash summary table 4-7 summarizes the data flash locations available to the user, including their default, minimum, and maximum values. table 4-7. data flash summary subclass data min max default class subclass offset name units id type value value value configuration 2 safety 0 ot chg i2 0 1200 550 0.1 c configuration 2 safety 2 ot chg time u1 0 60 2 s configuration 2 safety 3 ot chg recovery i2 0 1200 500 0.1 c configuration 2 safety 5 ot dsg i2 0 1200 600 0.1 c configuration 2 safety 7 ot dsg time u1 0 60 2 s configuration 2 safety 8 ot dsg recovery i2 0 1200 550 0.1 c charge inhibit configuration 32 0 charge inhibit temp low i2 C 400 1200 0 0.1 c temp low charge inhibit configuration 32 2 charge inhibit temp high i2 C 400 1200 450 0.1 c temp high temp configuration 32 4 temp hys i2 0 100 50 0.1 c hysteresis configuration 34 charge 2 charging voltage i2 0 4600 4200 mv configuration 34 charge 4 delta temp i2 0 500 50 0.1 c configuration 34 charge 6 suspend low temp i2 C 400 1200 -50 0.1 c configuration 34 charge 8 suspend high temp i2 C 400 1200 550 0.1 c charge configuration 36 2 taper current i2 0 1000 100 ma termination charge configuration 36 4 minimum taper charge i2 0 1000 25 0.01mah termination charge configuration 36 6 taper voltage i2 0 1000 100 mv termination charge configuration 36 8 current taper window u1 0 60 40 s termination charge configuration 36 11 fc set % i1 C 1 100 100 % termination charge configuration 36 12 fc clear % i1 C 1 100 98 % termination configuration 48 data 4 initial standby current i1 C 128 0 C 10 ma configuration 48 data 5 initial max load current i2 C 32,767 0 C 500 ma configuration 48 data 7 cc threshold i2 100 32,767 900 mah configuration 48 data 10 design capacity i2 0 65,535 1000 mah configuration 48 data 12 soh load i2 C 32,767 0 C 400 ma configuration 48 data 14 default temp i2 0 1000 250 (1) 0.1 c bq27520- configuration 48 data 16 device name s8 x x C g1 configuration 49 discharge 0 soc1 set threshold u1 0 255 150 mah configuration 49 discharge 1 soc1 clear threshold u1 0 255 175 mah configuration 49 discharge 5 sysdown set volt threshold i2 0 4200 3150 mv configuration 49 discharge 7 sysdown set volt time u1 0 60 2 s configuration 49 discharge 8 sysdown clear volt threshold i2 0 4200 3400 mv configuration 49 discharge 15 final voltage u2 0 4200 3000 mv configuration 56 integrity data 1 full reset counter u1 0 255 0 num manufacturer system data 57 0 C 31 block a [0 C 31] h1 0x00 0xff 0x00 C info manufacturer system data 57 32 C 63 block b [0 C 31] h1 0x00 0xff 0x00 C info (1) display as the value evsw displayed. data flash value is different. 24 general description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 table 4-7. data flash summary (continued) subclass data min max default class subclass offset name units id type value value value configuration 64 registers 0 operation configuration h2 0x0000 0xffff 0x0973 C configuration 64 registers 7 soc delta u1 0 25 1 % configuration 64 registers 8 u1 0 7 4 num i 2 c timeout configuration 64 registers 9 dfwrindwaittime u2 0 65535 0 5 s configuration 64 registers 11 opconfigb h1 0x00 0xff 0x50 C configuration 64 registers 12 opconfigc h1 0x00 0xff 0x28 C configuration 64 registers 13 clock control register h1 0x00 0x0f 0x00 C configuration 68 power 0 flash update ok voltage i2 0 4200 2800 mv configuration 68 power 7 sleep current i2 0 100 10 ma configuration 68 power 16 hibernate current u2 0 700 8 ma configuration 68 power 18 hibernate voltage u2 2400 3000 2550 mv configuration 68 power 21 max res factor u1 0 255 20 num configuration 68 power 22 min res factor u1 0 255 5 num gas gauging 80 it cfg 0 load select u1 0 255 1 C gas gauging 80 it cfg 1 load mode u1 0 255 0 C gas gauging 80 it cfg 24 ra filter u2 0 1000 800 num min % passed charge for gas gauging 80 it cfg 40 u1 1 100 37 % qmax gas gauging 80 it cfg 44 qmax filter u1 0 255 96 num gas gauging 80 it cfg 45 terminate voltage i2 C 32,768 32,767 3420 mv gas gauging 80 it cfg 50 user rate-ma i2 C 2000 C 100 0 ma gas gauging 80 it cfg 52 user rate-mw i2 C 7200 C 350 0 mw gas gauging 80 it cfg 54 reserve cap-mah i2 0 9000 0 mah gas gauging 80 it cfg 56 reserve cap-mwh i2 0 14,000 0 mwh gas gauging 80 it cfg 61 min delta voltage i2 C 32,000 32,000 0 mv gas gauging 80 it cfg 63 max sim rate u1 0 255 2 c/rate gas gauging 80 it cfg 64 min sim rate u1 0 255 20 c/rate gas gauging 80 it cfg 65 ra max delta u2 0 65,535 44 m gas gauging 80 it cfg 67 qmax max delta% u1 0 255 5 % gas gauging 80 it cfg 68 deltav max dv u2 0 65,535 10 mv current gas gauging 81 0 dsg current threshold i2 0 2000 60 ma thresholds current gas gauging 81 2 chg current threshold i2 0 2000 75 ma thresholds current gas gauging 81 4 quit current i2 0 1000 40 ma thresholds current gas gauging 81 6 dsg relax time u2 0 8191 60 s thresholds current gas gauging 81 8 chg relax time u1 0 255 60 s thresholds current gas gauging 81 9 quit relax time u1 0 63 1 s thresholds current gas gauging 81 10 transient factor charge u1 0 255 255 num thresholds current gas gauging 81 11 transient factor discharge u1 0 255 255 num thresholds current gas gauging 81 12 max ir correct u2 0 1,000 400 mv thresholds gas gauging 82 state 0 it enable h1 0x00 0x03 0x00 C gas gauging 82 state 1 application status h1 0x00 0xff 0x00 C gas gauging 82 state 2 qmax 0 i2 0 32,767 1000 mah gas gauging 82 state 4 cycle count 0 u2 0 65,535 0 C gas gauging 82 state 6 update status 0 h1 0x00 0x03 0x00 C copyright ? 2011, texas instruments incorporated general description 25 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com table 4-7. data flash summary (continued) subclass data min max default class subclass offset name units id type value value value gas gauging 82 state 7 qmax 1 i2 0 32767 1000 mah gas gauging 82 state 9 cycle count 1 u2 0 65,535 0 count gas gauging 82 state 11 update status 1 h1 0x00 0x03 0x00 C gas gauging 82 state 12 cell0 chg dod i2 0 16384 0 C gas gauging 82 state 14 cell1 chg dod at eoc i2 0 16384 0 C gas gauging 82 state 16 avg i last run i2 C 32,768 32,767 C 299 ma gas gauging 82 state 18 avg p last run i2 C 32,768 32,767 C 1131 mah gas gauging 82 state 20 delta voltage i2 C 32,768 32,768 2 mv calibration 104 data 0 cc gain f4 (2) 0.1 47 10 (3) mohm calibration 104 data 4 cc delta f4 (2) 4.7 188 10 (3) mohm calibration 104 data 8 cc offset i2 C 2.4 2.4 C 0.088 (3) mv calibration 104 data 10 adc offset i2 C 500 500 0 mv calibration 104 data 12 board offset i1 C 128 127 0 mv calibration 104 data 13 int temp offset i1 C 128 127 0 0.1 c calibration 104 data 14 ext temp offset i1 C 128 127 0 0.1 c calibration 104 data 15 pack v offset i1 C 128 127 0 mv calibration 107 current 1 deadband u1 0 255 5 ma security 112 codes 0 unseal key 0 h2 0x0000 0xffff 0x3672 C security 112 codes 2 unseal key 1 h2 0x0000 0xffff 0x0414 C security 112 codes 4 unsealed to full 0 h2 0x0000 0xffff 0xffff C security 112 codes 6 unsealed to full 1 h2 0x0000 0xffff 0xffff C security 112 codes 24 factrestorkey 0 h2 0x0000 0xffff 0x0def C security 112 codes 26 factrestorkey 1 h2 0x0000 0xffff 0x0fac C (2) not ieee floating point. (3) display as the value evsw displayed. data flash value is different. 5 functional description 5.1 fuel gauging the BQ27520-G1 measures the cell voltage, temperature, and current to determine battery soc. the BQ27520-G1 monitors charge and discharge activity by sensing the voltage across a small-value resistor (5 m ? to 20 m ? typ.) between the srp and srn pins and in series with the cell. by integrating charge passing through the battery, the battery s soc is adjusted during battery charge or discharge. the total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. when an application load is applied, the impedance of the cell is measured by comparing the ocv obtained from a predefined function for present soc with the measured voltage under load. measurements of ocv and charge integration determine chemical state of charge and chemical capacity (qmax). the initial qmax values are taken from a cell manufacturers' data sheet multiplied by the number of parallel cells. it is also used for the value in design capacity . the BQ27520-G1 acquires and updates the battery-impedance profile during normal battery usage. it uses this profile, along with soc and the qmax value, to determine fullchargecapacity( ) and stateofcharge( ) , specifically for the present load and temperature. fullchargecapacity( ) is reported as capacity available from a fully charged battery under the present load and temperature until voltage( ) reaches the terminate voltage . nominalavailablecapacity( ) and fullavailablecapacity( ) are the uncompensated (no or light load) versions of remainingcapacity( ) and fullchargecapacity( ) respectively. 26 functional description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 the BQ27520-G1 has two flags accessed by the flags( ) function that warns when the battery s soc has fallen to critical levels. when remainingcapacity( ) falls below the first capacity threshold, specified in so c1 set threshold , the [soc1] (state of charge initial) flag is set. the flag is cleared once remainingcapacity( ) rises above soc1 set threshold. the BQ27520-G1 s bat_low pin automatically reflects the status of the [soc1] flag. this flag is enabled when bl_int bit in operation configuration b is set. all units are in mah. when voltage( ) falls below the system shut down threshold voltage, sysdown set volt threshold , the [sysdown] flag is set, serving as a final warning to shut down the system. the soc_int also signals. when voltage( ) rises above sysdown clear voltage and the [sysdowm] flag has already been set, the [sysdown] flag is cleared. the soc_int also signals such change. all units are in mv. when the voltage is discharged to final voltage , the soc will be set as 0. 5.2 impedance track ? variables the BQ27520-G1 has several data flash variables that permit the user to customize the impedance track ? algorithm for optimized performance. these variables are dependent upon the power characteristics of the application as well as the cell itself. 5.2.1 load mode load mode is used to select either the constant-current or constant-power model for the impedance track ? algorithm as used in load select (see load select ). when load mode is 0, the constant current model is used (default). when 1, the constant power model is used. the [ldmd] bit of control_status reflects the status of load mode . 5.2.2 load select load select defines the type of power or current model to be used to compute load-compensated capacity in the impedance track ? algorithm. if load mode = 0 ( constant-current ) then the options presented in table 5-1 are available. table 5-1. constant-current model used when load mode = 0 loadselect value current model used average discharge current from previous cycle: there is an internal register that records the average discharge 0 current through each entire discharge cycle. the previous average is stored in this register. present average discharge current: this is the average discharge current from the beginning of this discharge cycle 1(default) until present time. 2 average current: based on averagecurrent( ) 3 current: based off of a low-pass-filtered version of averagecurrent( ) ( =14 s) 4 design capacity / 5: c rate based off of design capacity /5 or a c/5 rate in ma. 5 atrate (ma): use whatever current is in atrate( ) 6 user_rate-ma: use the value in user_rate-ma . this mode provides a completely user-configurable method. if load mode = 1 ( constant power ) then the following options shown in table 5-2 are available copyright ? 2011, texas instruments incorporated functional description 27 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com table 5-2. constant-power model used when load mode = 1 loadselect value power model used average discharge power from previous cycle: there is an internal register that records the average discharge power 0 through each entire discharge cycle. the previous average is stored in this register. present average discharge power: this is the average discharge power from the beginning of this discharge cycle 1(default) until present time. 2 average current voltage: based off the averagecurrent( ) and voltage( ) . 3 current voltage: based off of a low-pass-filtered version of averagecurrent( ) ( =14 s) and voltage( ) 4 design energy / 5: c rate based off of design energy /5 or a c/5 rate in ma. 5 atrate (10 mw): use whatever value is in atrate( ) . 6 user_rate-10mw: use the value in user_rate-10mw . this mode provides a completely user-configurable method. 5.2.3 reserve cap-mah reserve cap-mah determines how much actual remaining capacity exists after reaching 0 remainingcapacity( ) , before terminate voltage is reached. a no-load rate of compensation is applied to this reserve. 5.2.4 reserve cap-mwh reserve cap-mwh determines how much actual remaining capacity exists after reaching 0 availableenergy( ) , before terminate voltage is reached. a no-load rate of compensation is applied to this reserve capacity. 5.2.5 dsg current threshold this register is used as a threshold by many functions in the BQ27520-G1 to determine if actual discharge current is flowing into or out of the cell. the default for this register is in table 4-7 , which should be sufficient for most applications. this threshold should be set low enough to be below any normal application load current but high enough to prevent noise or drift from affecting the measurement. 5.2.6 chg current threshold this register is used as a threshold by many functions in the BQ27520-G1 to determine if actual charge current is flowing into or out of the cell. the default for this register is in table 4-7 , which should be sufficient for most applications. this threshold should be set low enough to be below any normal charge current but high enough to prevent noise or drift from affecting the measurement. 5.2.7 quit current, dsg relax time, chg relax time, and quit relax time the quit current is used as part of the impedance track ? algorithm to determine when the BQ27520-G1 enters relaxation mode from a current-flowing mode in either the charge direction or the discharge direction. the value of quit current is set to a default value in table 4-7 and should be above the standby current of the system. either of the following criteria must be met to enter relaxation mode: ? | averagecurrent( ) | < | quit current | for dsg relax time ? | averagecurrent( ) | < | quit current | for chg relax time after about 5 minutes in relaxation mode, the BQ27520-G1 attempts to take accurate ocv readings. an additional requirement of dv/dt < 4 v/s is required for the BQ27520-G1 to perform qmax updates. these updates are used in the impedance track ? algorithms. it is critical that the battery voltage be relaxed during ocv readings to and that the current is not be higher than c/20 when attempting to go into relaxation mode. quit relax time specifies the minimum time required for averagecurrent( ) to remain above the quitcurrent threshold before exiting relaxation mode. 28 functional description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 5.2.8 qmax 0 and qmax 1 generically called qmax , these dynamic variables contain the respective maximum chemical capacity of the active cell profiles, and are determined by comparing states of charge before and after applying the load with the amount of charge passed. they also correspond to capacity at a low rate of discharge, such as the c/20 rate. for high accuracy, this value is periodically updated by the BQ27520-G1 during operation. based on the battery cell capacity information, the initial value of chemical capacity should be entered in the qmax n field for each default cell profile. the impedance track ? algorithm updates these values and maintains them the associated actual cell profiles. 5.2.9 update status 0 and update status 1 bit 0 (0x01) of the update status n registers indicates that the BQ27520-G1 has learned new qmax parameters and is accurate. the remaining bits are reserved. bits 0 is user-configurable; however, it is also a status flag that can be set by the BQ27520-G1. bit 0 should never be modified except when creating a golden image file as explained in the application note preparing optimized default flash constants for specific battery types ( slua334 ). bit 0 is updated as needed by the BQ27520-G1. 5.2.10 avg i last run the BQ27520-G1 logs the current averaged from the beginning to the end of each discharge cycle. it stores this average current from the previous discharge cycle in this register. this register should not be modified. it is only updated by the BQ27520-G1 when required. 5.2.11 avg p last run the BQ27520-G1 logs the power averaged from the beginning to the end of each discharge cycle. it stores this average power from the previous discharge cycle in this register. to get a correct average power reading the BQ27520-G1 continuously multiplies instantaneous current times voltage( ) to get power. it then logs this data to derive the average power. this register should not be modified. it is only updated by the BQ27520-G1 when required. 5.2.12 delta voltage the BQ27520-G1 stores the maximum difference of voltage( ) during short load spikes and normal load, so the impedance track ? algorithm can calculate remaining capacity for pulsed loads. it is not recommended to change this value. 5.2.13 default ra and ra tables these tables contain encoded data and, with the exception of the default ra tables , are automatically updated during device operation. no user changes should be made except for reading/writing the values from a pre-learned pack (part of the process for creating golden image files). 5.3 detailed pin description 5.3.1 the operation configuration register some BQ27520-G1 pins are configured via the operation configuration data flash register, as indicated in table 5-3 . this register is programmed/read via the methods described in section 4.2.1 , accessing the data flash. the register is located at subclass = 64, offset = 0. copyright ? 2011, texas instruments incorporated functional description 29 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com table 5-3. operation configuration bit definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 high byte rescap batg_ovr int_brem pfc_cfg1 pfc_cfg0 iwake rsns1 rsns0 low byte int_focv idselen sleep rmfcc soci_pol batg_pol batl_pol temps rescap = no-load rate of compensation is applied to the reserve capacity calculation. true when set. default is 0. batg_ovr = bat_gd override bit. if the gauge enters hibernate only due to the cell voltage, the bat_gd pin will not negate. true when set. default is 0. int_brem = battery removal interrupt bit. the soc_int pulses 1ms when the battery removal interrupt is enabled. true when set. the default is 0. pfc_cfg1/pfc_cfg0 = pin function code (pfc) mode selection: pfc 0, 1, or 2 selected by 0/0, 0/1, or 1/0, respectively. default is pfc 1 (0/1). iwake/rsns1/rsns0 = these bits configure the current wake function (see table 5-7 ). default is 0/0/1. int_focv = indication of the measurement of the ocv during the initialization. the soc_int will pulse during the first measurement if this bit is set. true when set. default is 0. idselen = enables cell profile selection feature. true when set. default is 1. sleep = the fuel gauge can enter sleep, if operating conditions allow. true when set. default is 1. rmfcc = rm is updated with the value from fcc, on valid charge termination. true when set. default is 1. soci_pol = soc interrupt polarity is active-low. true when cleared. default is 0. batg_pol = bat_gd pin is active-low. true when cleared. default is 0. batl_pol = bat_low pin is active-high. true when set. default is 1. temps = selects external thermistor for temperature( ) measurements. true when set. default is 1. some BQ27520-G1 pins are configured via the operation configuration b data flash register, as indicated in table 5-4 . this register is programmed/read via the methods described in section 4.2.1: accessing the data flash. the register is located at subclass = 64, offset = 9. table 5-4. operation configuration b bit definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 rsvd0 bie bl_int gndsel rsvd dfwrindbl rfactstep indfacres rsvd0 = reserved. must set to 0. bie = battery insertion detection enable. when the battery insertion detection is disabled, the gauge relies on the host command to set the bat_det bit. true when set. default is 1. bl_int = battery low interrupt enable. true when set. default is 0. gndsel = the adc ground select control. the vss (pin d1) is selected as ground reference when the bit is clear. pin a1 is selected when the bit is set. default is 0. dfwrindbl = dataflash write indication. soc_int is used for indication if the bit is clear. bat_low is used for indication if the bit is set. default is 0. rfactstep = enables ra step up/down to min/max res factor before disabling ra updates. default is 1. indfacres = enables soc_int pin to assert during factory_restore subcommand execution . default is 1. table 5-5. operation configuration c bit definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 batgspuen batgwpuen batlspuen batlwpuen rsvd slpwkchg deltavopt1 deltavopt0 batgspuen = bat_gd pin strong pull-up enable. default is 0. batgwpuen = bat_gd pin weak pull-up enable. default is 0. batlspuen = bat_low pin strong pull-up enable. default is 1. batlwpuen = bat_low pin weak pull-up enable. default is 0. slpwkchg = enables compensation for the passed charge missed when waking from sleep mode. default is 1. deltavopt[1:0] = configures options for determination of delta voltage which is defined as the maximum difference in voltage( ) during normal load and short load spikes. delta voltage is a used as a compensation factor for calculating for remainingcapacity( ) under pulsed loads. default is 0/0. 0/0 = standard deltav. average variance from steady state voltage used to determine end of discharge voltage. (default) 0/1 = no averaging. the last instantaneous change in voltage( ) from steady state is used to determine the end of discharge voltage. 1/0 = use the value in min delta voltage . 1/1 = not used. 5.3.2 pin function code descriptions the BQ27520-G1 has three possible pin-function variations that can be selected in accordance with the circuit architecture of the end application. each variation has been assigned a pin function code, or pfc. when the pfc is set to 0, only the BQ27520-G1 measures battery temperature under discharge and relaxation conditions. the charger does not receive any information from the BQ27520-G1 about the temperature readings, and therefore operates open-loop with respect to battery temperature. 30 functional description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 a pfc of 1 is like a pfc of 0, except temperature is also monitored during battery charging. if charging temperature falls outside of the preset range defined in data flash, a charger can be disabled via the bat_gd pin until cell temperature recovers. see section 5.6.2 , charge inhibit and suspend , for additional details. finally when the pfc is set to 2, the battery thermistor can be shared between the fuel gauge and the charger. the charger has full usage of the thermistor during battery charging, while the fuel gauge uses the thermistor exclusively during discharge and battery relaxation. when pfc = 0 or 2, the BQ27520-G1 must be queried by the system in order to determine the battery temperature. at that time, the BQ27520-G1 samples the temperature. this saves battery energy when operating from battery, as periodic temperature updates are avoided during charging mode. note: due to thermistor sharing limitations, temperature data is not available during battery charging with pfc = 2. the pfc is specified in operation configuration [pfc_cfg1, pfc_cfg0] . the default is pfc = 1. 5.3.3 bat_low pin the bat_low pin provides a system processor with an electrical indicator of battery status. the signaling on the bat_low pin follows the status of the [soc1] bit in the flags( ) register. note that the polarity of the bat_low pin can be inverted via the [batl_pol] bit of operation configuration . 5.3.4 power path control with the bat_gd pin the BQ27520-G1 must operate in conjunction with other electronics in a system appliance, such as chargers or other ics and application circuits that draw appreciable power. after a battery is inserted into the system, there should be no charging current or a discharging current higher than c/20, so that an accurate ocv can be read. the ocv is used for helping determine which battery profile to use, as it constitutes part of the battery impedance measurement when a battery is inserted into a system, the impedance track ? algorithm requires that no charging of the battery takes place and that any discharge is limited to less than c/20 these conditions are sufficient for the fuel gauge to take an accurate ocv reading. to disable these functions, the bat_gd pin is merely negated from the default setting. once an ocv reading has be made, the bat_gd pin is asserted, thereby enabling battery charging and regular discharge of the battery. the operation configuration [batg_pol] bit can be used to set the polarity of the battery good signal, should the default configuration need to be changed. copyright ? 2011, texas instruments incorporated functional description 31 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com figure 5-1. power mode diagram figure 5-1 details how the bat_gd pin functions in the context of battery insertion and removal, as well as normal vs. sleep modes. in pfc 1, the bat_gd pin is also used to disable battery charging when the BQ27520-G1 reads battery temperatures outside the range defined by [charge inhibit temp low, charge inhibit temp high] . the bat_gd line is asserted once temperature falls within the range [charge inhibit temp low + temp hys, charge inhibit temp high C temp hys] . 5.3.5 battery detection using the bi/tout pin during power-up or hibernate activities, or any other activity where the BQ27520-G1 needs to determine whether a battery is connected or not, the fuel gauge applies a test for battery presence. first, the bi/tout pin is put into high-z status. the weak 1.8m ? pull-up resistor will keep the pin high while no battery is present. when a battery is inserted (or is already inserted) into the system device, the bi/tout pin will be pulled low. this state is detected by the fuel gauge, which polls this pin every second when the gauge has power. a battery-disconnected status is assumed when the BQ27520-G1 reads a thermistor voltage that is near 2.5v. 32 functional description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1 system sleep exit from sleep | averagecurrent( ) | > sleep current or current is detected above i wake exit from sleep (host has set control status [hibernate] = 1 or v cell < hibernate voltage fuel gauging and data updated every 1s normal fuel gauging and data updated every 20 seconds (lfo on and hfo off) sleep disable all bq27520 subcircuits except gpio. negate bat_gd hibernate entry to sleep operation configuration [sleep] = 1 and | averagecurrent( ) | sleep current and control status [snooze] = 0 wakeup from hibernate communication activity and comm address is not for bq27520 exit from hibernate battery removed por check for battery insertion from halt state. no gauging bat insert check entry to normal flags [bat _det] = 1 exit from normal flags [bat _det] = 0 exit from sleep flags [bat_det] = 0 flags [bat _det] = 0 wait_hibernate fuel gauging and data updated every 20 seconds bat_gd unchanged exit from wait_hibernate cell relaxed and | averagecurrent() | < hibernate current or cell relaxed and v cell < hibernate voltage system shutdown exit from wait _hibernate host must set control status [hibernate ] = 0 and v cell > hibernate voltage exit from hibernate communication activity and comm address is for bq27520 bq27520 clears control status [hibernate ] = 0 recommend host also set control status [hibernate] = 0 fuel gauging and data updated every 20 seconds both lfo and hfo are on sleep+ entry to sleep+ operation configuration [sleep] = 1 and control status [snooze] = 1 and | averagecurrent( ) | sleep current exit from sleep+ any communication to the gauge or | averagecurrent( ) | > sleep current or current is detected above i wake entry to sleep+ control status [snooze] = 0 entry to sleep+ control status [snooze] = 1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 5.3.6 soc_int pin the soc_int pin generates a pulse of different pulse widths under various conditions as indicated by the table below. after initialization only one soc_int pulse will be generated within any given one second time slot and therefore, may indicate multiple event conditions. table 5-6. soc_int pulse condition and width enable condition pulse width comment during charge, when the soc is greater than ( > ) the points, 100% - n soc_delta and 100%; soc_delta during discharge, when the soc reaches ( ) the points 100% - n soc_delta 0 1 ms point soc_delta and 0%; where n is an integer starting from 0 to the number generating soc no less than 0% soc1 set always 1 ms when rsoc reached the soc1 set or clear threshold set in the data flash and bl_int bit in operation configuration b is set. soc1 clear always 1 ms sysdown set always 1 ms when the battery voltage reached the sysdown set or clear threshold sysdown set in the data flash always 1 ms clear state when there is a state change including charging, discharging and soc_delta 0 1 ms change relaxation. this function is disabled when soc_delta is set to 0. battery int_brem bit is set in removal opconfig and bie bit is 1ms this function is disabled when bie is cleared. set about 165ms. same soc_int pulses for the ocv command after the initialization. ocv as the ocv after initialization command command execution time period about 165ms. same this command is to generate the soc_int pulse during the ocv int_focv bit is set in as the ocv initialization. command opconfig command execution time period programmable pulse soc_int is used to indicate the data flash update. the gauge will wait data flash after initialization and width flash (see dfwrindwaittime times 5 s after the soc_int signal to start the write dfwrindwaittime 0 comment) data flash update. this function is disabled if dfwrindwaittime is set to 0. copyright ? 2011, texas instruments incorporated functional description 33 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 5.4 temperature measurement the BQ27520-G1 measures battery temperature via its ts input, in order to supply battery temperature status information to the fuel gauging algorithm and charger-control sections of the gauge. alternatively, it can also measure internal temperature via its on-chip temperature sensor, but only if the [temps] bit of the operation configuration register is cleared. the [gndsel] bit of operation configuration b register selects the ground reference of the adc converter for temperature measurement. regardless of which sensor is used for measurement, a system processor can request the current battery temperature by calling the temperature( ) function (see section 4.1.1 , standard data commands , for specific information). the thermistor circuit requires the use of an external ntc 103at-type thermistor. additional circuit information for connecting this thermistor to the BQ27520-G1 is shown in section 8 , reference schematic . 5.5 overtemperature indication 5.5.1 overtemperature: charge if during charging, temperature( ) reaches the threshold of ot chg for a period of ot chg time and averagecurrent( ) > chg current threshold , then the [otc] bit of flags( ) is set. when temperature( ) falls to ot chg recovery , the [otc] of flags( ) is reset. if ot chg time = 0, then the feature is completely disabled. 5.5.2 overtemperature: discharge if during discharging, temperature( ) reaches the threshold of ot dsg for a period of ot dsg time , and averagecurrent( ) C dsg current threshold , then the [otd] bit of flags( ) is set. when temperature( ) falls to ot dsg recovery , the [otd] bit of flags( ) is reset. if ot dsg time = 0, then feature is completely disabled. 5.6 charging and charge-termination indication 5.6.1 detecting charge termination for proper BQ27520-G1 operation, the cell charging voltage must be specified by the user. the default value for this variable is charging voltage table 4-7 . the BQ27520-G1 detects charge termination when (1) during 2 consecutive periods of current taper window , the averagecurrent( ) is < taper current , (2) during the same periods, the accumulated change in capacity > min taper charge / current taper window , and (3) voltage( ) > charging voltage C taper voltage . when this occurs, the [chg] bit of flags( ) is cleared. also, if the [rmfcc] bit of operation configuration is set, then remainingcapacity( ) is set equal to fullchargecapacity( ) . 5.6.2 charge inhibit and suspend the BQ27520-G1 can indicate when battery temperature has fallen below or risen above predefined thresholds charge inhibit temp low or charge inhibit temp high , respectively. in this mode, the [chg_int] bit is set and the bat_gd pin is deserted to indicate this condition. the [chg_int] bit is cleared and the bat_gd pin is asserted once the battery temperature returns to the range [charge inhibit temp low + temp hys, charge inhibit temp high C temp hys] . when pfc = 1, the BQ27520-G1 can indicate when battery temperature has fallen below or risen above predefined thresholds suspend low temp or suspend high temp , respectively. in this mode, the [xchg] bit is set to indicate this condition. the [xchg] bit is cleared once the battery temperature returns to the range [suspend low temp + temp hys, suspend high temp C temp hys] . 34 functional description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 the charging should not start when the temperature is below the charge inhibit temp low or above the charge inhibit temp high. the charging can continue if the charging starts inside the window [charge inhibit temp low, charge inhibit temp high] until the temperature is either below suspend low temp or above the suspend low temp. therefore, the window [charge inhibit temp low, charge inhibit temp high] must be inside the window of [suspend low temp, suspend high temp]. 5.7 power modes the BQ27520-G1 has different power modes: bat insert check, normal, sleep, sleep+ and hibernate. in normal mode, the BQ27520-G1 is fully powered and can execute any allowable task. in sleep+ mode, both low frequency and high frequency oscillators are active. although the sleep+ has higher current consumption than the sleep mode, it is also a reduced power mode. in sleep mode, the fuel gauge turns off the high frequency oscillator and exists in a reduced-power state, periodically taking measurements and performing calculations. in hibernate mode, the fuel gauge is in a low power state, but can be woken up by communication or certain i/o activity. finally, the bat insert check mode is a powered-up, but low-power halted, state, where the BQ27520-G1 resides when no battery is inserted into the system. the relationship between these modes is shown in figure 5-1 . 5.7.1 bat insert check mode this mode is a halted-cpu state that occurs when an adapter, or other power source, is present to power the BQ27520-G1 (and system), yet no battery has been detected. when battery insertion is detected, a series of initialization activities begin, which include: ocv measurement, setting the bat_gd pin, and selecting the appropriate battery profiles. some commands, issued by a system processor, can be processed while the BQ27520-G1 is halted in this mode. the gauge will wake up to process the command, then return to the halted state awaiting battery insertion. 5.7.2 normal mode the fuel gauge is in normal mode when not in any other power mode. during this mode, averagecurrent( ) , voltage( ) and temperature( ) measurements are taken, and the interface data set is updated. decisions to change states are also made. this mode is exited by activating a different power mode. because the gauge consumes the most power in normal mode, the impedance track ? algorithm minimizes the time the fuel gauge remains in this mode. 5.7.3 sleep mode sleep mode is entered automatically if the feature is enabled ( operation configuration [sleep] = 1) and averagecurrent( ) is below the programmable level sleep current . once entry into sleep mode has been qualified, but prior to entering it, the BQ27520-G1 performs an coulomb counter autocalibration to minimize offset. during sleep mode, the BQ27520-G1 periodically takes data measurements and updates its data set. however, a majority of its time is spent in an idle condition. the BQ27520-G1 exits sleep if any entry condition is broken, specifically when (1) averagecurrent( ) rises above sleep current , or (2) a current in excess of i wake through r sense is detected. in the event that a battery is removed from the system while a charger is present (and powering the gauge), impedance track ? updates are not necessary. hence, the fuel gauge enters a state that checks for battery insertion and does not continue executing the impedance track ? algorithm. copyright ? 2011, texas instruments incorporated functional description 35 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 5.7.4 sleep+ mode compared to the sleep mode, sleep+ mode has the high frequency oscillator in operation. the communication delay could be eliminated. the sleep+ is entered automatically if the feature is enabled ( control status [snooze] = 1) and averagecurrent( ) is below the programmable level sleep current . during sleep+ mode, the BQ27520-G1 periodically takes data measurements and updates its data set. however, a majority of its time is spent in an idle condition. the BQ27520-G1 exits sleep+ if any entry condition is broken, specifically when (1) any communication activity with the gauge, or (2) averagecurrent( ) rises above sleep current , or (3) a current in excess of i wake through r sense is detected. 5.7.5 hibernate mode hibernate mode should be used when the system equipment needs to enter a low-power state, and minimal gauge power consumption is required. this mode is ideal when a system equipment is set to its own hibernate, shutdown, or off modes. before the fuel gauge can enter hibernate mode, the system must set the [hibernate] bit of the control_status register. the gauge waits to enter hibernate mode until it has taken a valid ocv measurement and the magnitude of the average cell current has fallen below hibernate current . the gauge can also enter hibernate mode if the cell voltage falls below hibernate voltage and a valid ocv measurement has been taken. the gauge will remain in hibernate mode until the system issues a direct i 2 c command to the gauge or a por occurs. i 2 c communication that is not directed to the gauge will not wake the gauge. it is important that bat_gd be deserted status (no battery charging/discharging). this prevents a charger application from inadvertently charging the battery before an ocv reading can be taken. it is the system s responsibility to wake the BQ27520-G1 after it has gone into hibernate mode. after waking, the gauge can proceed with the initialization of the battery information (ocv, profile selection, etc.) 5.8 power control 5.8.1 wake-up comparator the wake up comparator is used to indicate a change in cell current while the BQ27520-G1 is in sleep mode. operation configuration uses bits [rsns1 C rsns0] to set the sense resistor selection. operation configuration also uses the [iwake] bit to select one of two possible voltage threshold ranges for the given sense resistor selection. an internal interrupt is generated when the threshold is breached in either the charge or discharge direction. setting both [rsns1] and [rsns0] to 0 disables this feature. 36 functional description copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 table 5-7. i wake threshold settings (1) rsns1 rsns0 iwake vth(srp C srn) 0 0 0 disabled 0 0 1 disabled 0 1 0 1.0 mv or C 1.0 mv 0 1 1 2.2 mv or C 2.2 mv 1 0 0 2.2 mv or C 2.2 mv 1 0 1 4.6 mv or C 4.6 mv 1 1 0 4.6 mv or C 4.6 mv 1 1 1 9.8 mv or C 9.8 mv (1) the actual resistance value vs the setting of the sense resistor is not important, just the actual voltage threshold when calculating the configuration. the voltage thresholds are typical values under room temperature. 5.8.2 flash updates data flash can only be updated if voltage( ) flash update ok voltage . flash programming current can cause an increase in ldo dropout. the value of flash update ok voltage should be selected such that the BQ27520-G1 v cc voltage does not fall below its minimum of 2.4 v during flash write operations. 5.9 autocalibration the BQ27520-G1 provides an autocalibration feature that measures the voltage offset error across srp and srn as operating conditions change. it subtracts the resulting offset error from normal sense resistor voltage, v sr , for maximum measurement accuracy. autocalibration of the coulomb counter begins on entry to sleep mode, except if temperature( ) is 5 c or temperature( ) 45 c. the fuel gauge also performs a single offset when (1) the condition of averagecurrent( ) 100 ma and (2) {voltage change since last offset calibration 256 mv} or {temperature change since last offset calibration is greater than 8 c for 60 s}. capacity and current measurements continue at the last measured rate during the offset calibration when these measurements cannot be performed. if the battery voltage drops more than 32 mv during the offset calibration, the load current has likely increased; hence, the offset calibration is aborted. 6 application-specific information 6.1 battery profile storage and selection 6.1.1 common profile aspects when a battery pack is removed from host equipment, the BQ27520-G1 maintains some of the battery information in case the battery is re-inserted. this way, the impedance track ? algorithm has a mean of recovering battery-status information, thereby maintaining good state-of-charge (soc) estimates. two default battery profiles are available to store battery information. they are used to provide the impedance track ? algorithm with the default information on two possible battery types expected to be used with the end-equipment. these default profiles can be used to support batteries of different chemistry, same chemistry but different capacities, or same chemistry but different models. default profiles are programmed by the end-equipment manufacturer. however, only one of the default profiles can be selected, and this selection cannot be changed during end-equipment operation. in addition to the default profiles, the fuel gauge maintains two profiles pack0 and pack1. these tables hold dynamic battery data, and keep track of the status for up to two of the most recent batteries used. in most cases, the fuel gauge can manage the information on two removable battery packs. copyright ? 2011, texas instruments incorporated application-specific information 37 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 6.1.2 activities upon pack insertion 6.1.2.1 first ocv and impedance measurement at power-up the bat_gd pin is inactive, so that the system might not obtain power from the battery (this depends on actual implementation). in this state, the battery should be put in a condition with load current less than c/20. next, the BQ27520-G1 measures its first open-circuit voltage (ocv) via the bat pin. the [ocvcmdcomp] bit will set once the ocv measurement is completed. depending on the load current, the [ocvfail] bit indicates whether the ocv reading is valid. from the ocv(soc) table, the soc of the inserted battery is found. then the bat_gd pin is made active, and the impedance of the inserted battery is calculated from the measured voltage and the load current: z(soc) = ( ocv(soc) C v ) / i. this impedance is compared with the impedance of the dynamic profiles, packn , and the default profiles, defn , for the same soc (the letter n depicts either a 0 or 1 ).the [initcomp] bit will be set afterwards and the ocv command could be issued 6.1.3 reading application status the application status data flash location contains cell profile status information, and can be read using the applicationstatus( ) extended command (0x6a). the bit configuration of this function/location is shown in table 6-1 . table 6-1. applicationstatus( ) bit definitions. application bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 configuration byte lu_ prof lu_prof = last profile used by fuel gauge. cell0 last used when cleared. cell1 last used when set. default is 0. 6.2 application-specific flow and control the BQ27520-G1 supports only one type of battery profile. this profile is stored in both the def0 and def1 profiles. when a battery pack is inserted for the first time, the default profile is copied into the packn profiles. then the impedance track ? algorithm begins gas gauging, regularly updating packn as the battery is used. when an existing pack is removed from the BQ27520-G1 and a different (or same) pack is inserted, cell impedance is measured immediately after battery detection (see section 6.1.2.1., first ocv and impedance measurement ). the BQ27520-G1 chooses the profile which is closest to the measured impedance, starting with the packn profiles. that is, if the measured impedance matches pack0 , then the pack0 profile is used. if the measured impedance matches pack1 , then the pack1 profile is used. if the measured impedance does not match the impedance stored in either pack0 or pack1 , the battery pack is deemed new (none of the previously used packs). either def0/def1 profile is copied into either the pack0 or pack1 profile, overwriting the oldest packn profile. 38 application-specific information copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 7 communications 7.1 i 2 c interface the BQ27520-G1 supports the standard i 2 c read, incremental read, quick read, one byte write, and incremental write functions. the 7 bit device address (addr) is the most significant 7 bits of the hex address and is fixed as 1010101. the first 8-bits of the i2c protocol will; therefore, be 0xaa or 0xab for write or read, respectively. the quick read returns data at the address indicated by the address pointer. the address pointer, a register internal to the i 2 c communication engine, will increment whenever data is acknowledged by the BQ27520-G1 or the i 2 c master. quick writes function in the same manner and are a convenient means of sending multiple bytes to consecutive command locations (such as two-byte commands that require two bytes of data) the following command sequences are not supported: attempt to write a read-only address (nack after data sent by master): attempt to read an address above 0x6b (nack command): copyright ? 2011, texas instruments incorporated communications 39 submit documentation feedback focus.ti.com: BQ27520-G1 host generated a a s 0 addr[6:0] cmd [7:0] sr 1 addr[6:0] a data [7:0] a data [7:0] p n . . . (d) incremental read a a s 0 addr[6:0] cmd [7:0] sr 1 addr[6:0] a data [7:0] p n (c) 1- byte read a a s a 0 p addr[6:0] cmd [7:0] data [7:0] (a) 1-byte write (b) quick read s 1 addr[6:0] a data [7:0] p n bq27520 generated . . . a a s a 0 p addr[6:0] cmd[7:0] data [7:0] data [7:0] a a (e) incremental write (s = start , sr = repeated start , a = acknowledge , n = no acknowledge , and p = stop).
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 7.2 i 2 c time out the i 2 c engine will release both sda and scl if the i 2 c bus is held low for the time defined by i 2 c timeout times 0.5 second. if the BQ27520-G1 was holding the lines, releasing them will free for the master to drive the lines. if an external condition is holding either of the lines low, the i 2 c engine will enter the low power sleep mode. 7.3 i 2 c command waiting time to make sure the correct results of a command with the 400khz i 2 c operation, a proper waiting time should be added between issuing command and reading results. for subcommands, the following diagram shows the waiting time required between issuing the control command the reading the status with the exception of checksum and ocv commands. a 100ms waiting time is required between the checksum command and reading result, and a 1.2 second waiting time is required between the ocv command and result. for read-write standard command, a minimum of 2 seconds is required to get the result updated. for read-only standard commands, there is no waiting time required, but the host should not issue all standard commands more than two times per second. otherwise, the gauge could result in a reset issue due to the expiration of the watchdog timer. the i 2 c clock stretch could happen in a typical application. a maximum 80ms clock stretch could be observed during the flash updates. there is up to 270ms clock stretch after the ocv command is issued. 7.4 i 2 c clock stretching i 2 c clock stretches can occur during all modes of fuel gauge operation. in the fullsleep and hibernate modes, a clock stretch will occur on all i2c bus traffic as the device must wake-up to process the packet. the data flash clock control register can be configured with a value of 0x09 in order to minimize the wake-up clock stretch period to approximately 32us; while a clock control register value of 0x00 configures a longer wake-up clock stretch period of approximately 4ms used in previous bq2750x devices. any other value used in the clock control register may result in unpredictable clock stretch timing. in normal and sleep modes, clock stretching will only occur for packets addressed for the fuel gauge. the timing of stretches will vary as interactions between the communicating host and the gauge are asynchronous. the i 2 c clock stretches may occur after start bits, the ack/nak bit and first data bit transmit on a host read cycle. the majority of clock stretch periods are small ( < = 4msec) as the i2c interface peripheral and cpu firmware perform normal data flow control. however, less frequent but more significant clock stretch periods may occur when data flash (df) is being written by the cpu to update the resistance (ra) tables and other df parameters such as qmax. due to the organization of df, updates need to be written in data blocks consisting of multiple data bytes. an ra table update requires erasing a single page of df, programming the updated ra table and a flag. the potential i 2 c clock stretching time is 24ms max. this includes 20ms page erase and 2ms row programming time (x2 rows). the ra table updates occur during the discharge cycle and at up to 15 resistance grid points that occur during the discharge cycle. 40 communications copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1 a a s 0 addr [6:0] cmd [7:0] sr 1 addr [6:0] a data [7:0] a data [7:0] p n a a s a 0 p addr [6:0] cmd [7:0] data [7:0] data [7:0] a 66 s m a a s 0 addr [6:0] cmd [7:0] sr 1 addr [6:0] a data [7:0] a data [7:0] a data [7:0] a data [7:0] p n waiting time between control subcommand and reading results waiting time between continuous reading results 66 s m 66 s m
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 a df block write typically requires a max of 72ms. this includes copying data to a temporary buffer and updating df. this temporary buffer mechanism is used to protect from power failure during a df update. the first part of the update requires 20ms time to erase the copy buffer page, 6 ms time to write the data into the copy buffer and the program progress indicator (2ms for each individual write). the second part of the update is writing to the df and requires 44ms df block update time. this includes a 20ms each page erase for two pages and 2ms each row write for two rows. in the event that a previous df write was interrupted by a power failure or reset during the df write, an additional 44ms max df restore time is required to recover the data from a previously interrupted df write. in this power failure recovery case, the total i 2 c clock stretching is 116ms max. another case where i 2 c clock stretches is at the end of discharge. the update to the last discharge data will go through the df block update twice because two pages are used for the data storage. the clock stretching in this case is 144ms max. this occurs if there has been a ra table update during the discharge. copyright ? 2011, texas instruments incorporated communications 41 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com 8 reference schematics 8.1 schematic 42 reference schematics copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 www.ti.com slus955a C jan 2011 C revised august 2011 8.2 package dimensions d e max = 2640 m max = 1986 m min = 2580 m min = 1926 m copyright ? 2011, texas instruments incorporated reference schematics 43 submit documentation feedback focus.ti.com: BQ27520-G1
BQ27520-G1 slus955a C jan 2011 C revised august 2011 www.ti.com revision history note: page numbers for previous revisions may differ from page numbers in the current version. changes from original (june 2010) to a revision ......................................................................................................... page ? changed section 4.1.1.4 - temperature( ) : 0x06/0x07 ........................................................................ 16 ? changed table 5-4, bit7 from: wrtemp to: rsvd0. host temperature write is not supported ..................... 30 44 reference schematics copyright ? 2011, texas instruments incorporated submit documentation feedback focus.ti.com: BQ27520-G1
package option addendum www.ti.com 11-apr-2013 addendum-page 1 packaging information orderable device status (1) package type package drawing pins package qty eco plan (2) lead/ball finish msl peak temp (3) op temp (c) top-side markings (4) samples bq27520yzfr-g1 nrnd dsbga yzf 15 3000 green (rohs & no sb/br) snagcu level-1-260c-unlim -40 to 85 bq27520g bq27520yzft-g1 nrnd dsbga yzf 15 250 green (rohs & no sb/br) snagcu level-1-260c-unlim -40 to 85 bq27520g (1) the marketing status values are defined as follows: active: product device recommended for new designs. lifebuy: ti has announced that the device will be discontinued, and a lifetime-buy period is in effect. nrnd: not recommended for new designs. device is in production to support existing customers, but ti does not recommend using this part in a new design. preview: device has been announced but is not in production. samples may or may not be available. obsolete: ti has discontinued the production of the device. (2) eco plan - the planned eco-friendly classification: pb-free (rohs), pb-free (rohs exempt), or green (rohs & no sb/br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. tbd: the pb-free/green conversion plan has not been defined. pb-free (rohs): ti's terms "lead-free" or "pb-free" mean semiconductor products that are compatible with the current rohs requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. where designed to be soldered at high temperatures, ti pb-free products are suitable for use in specified lead-free processes. pb-free (rohs exempt): this component has a rohs exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. the component is otherwise considered pb-free (rohs compatible) as defined above. green (rohs & no sb/br): ti defines "green" to mean pb-free (rohs compatible), and free of bromine (br) and antimony (sb) based flame retardants (br or sb do not exceed 0.1% by weight in homogeneous material) (3) msl, peak temp. -- the moisture sensitivity level rating according to the jedec industry standard classifications, and peak solder temperature. (4) multiple top-side markings will be inside parentheses. only one top-side marking contained in parentheses and separated by a "~" will appear on a device. if a line is indented then it is a continuation of the previous line and the two combined represent the entire top-side marking for that device. important information and disclaimer: the information provided on this page represents ti's knowledge and belief as of the date that it is provided. ti bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. efforts are underway to better integrate information from third parties. ti has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. ti and ti suppliers consider certain information to be proprietary, and thus cas numbers and other limited information may not be available for release. in no event shall ti's liability arising out of such information exceed the total purchase price of the ti part(s) at issue in this document sold by ti to customer on an annual basis.
tape and reel information *all dimensions are nominal device package type package drawing pins spq reel diameter (mm) reel width w1 (mm) a0 (mm) b0 (mm) k0 (mm) p1 (mm) w (mm) pin1 quadrant bq27520yzft-g1 dsbga yzf 15 250 180.0 8.4 2.1 2.76 0.81 4.0 8.0 q1 package materials information www.ti.com 24-aug-2013 pack materials-page 1
*all dimensions are nominal device package type package drawing pins spq length (mm) width (mm) height (mm) bq27520yzft-g1 dsbga yzf 15 250 182.0 182.0 17.0 package materials information www.ti.com 24-aug-2013 pack materials-page 2

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