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i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 1 of 31 all rights reserved revision 1.0 5 october 2015 IQS227AS datasheet iq switch ? - proxsense ? series single channel capacitive proximity/touch controller the iqs227 a s proxsense ? ic is a ful ly integrated self c apacitive sensor with d ual outpu ts (touch and proximity output s ). features ? sub 2 .5 a in low power mode while sensing proximity ? a utomatic t uning i mplementation (ati) - automatic tuning of sense electrode ? i nternal c apacitor i mplementation (ici ) C reference capacitor on - chip ? supply voltage: 1.8v to 3.6v ? minimum external components ? data streaming option ? advanced o n - chip digital signal processing ? user selectable (otp) : 4 power modes io sink / source time - out for stuck key output mode (direct / latch / toggle) proximity and touch button sensitivity applications ? lcd, plasma & led tvs ? gsm cellular telephones C on ear detection / touch keys ? led flashlights or headlamps ? white goods and appliances ? office e quipment , toys, sanitary ware ? flame p roof, h azardous environment human interface devices ? proximity d etection enables backlighting activation ? wake - up from standby applications ? replacement for electromechanical switches ? find - in - the - dark (fitd) applications ? automotive: door pocket l ighting, electric window control ? gui trigger on proximity detected available options t a tsot23 - 6 - 40 c to 85 c IQS227AS 6 pin tsot23 - 6 representations only, not actual markings rohs2 compliant
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 2 of 31 all rights reserved revision 1.0 5 october 2015 contents IQS227AS datasheet ................................ ................................ ................................ ................................ ................ 1 1 overview ................................ ................................ ................................ ................................ ......................... 4 2 analogue functio nality ................................ ................................ ................................ ............................... 4 3 packaging and pin - out ................................ ................................ ................................ ................................ . 5 4 user configurable op tions ................................ ................................ ................................ .......................... 7 5 measuring capacitanc e using the charge transfer method ................................ ............................... 10 6 descriptions of user options ................................ ................................ ................................ ..................... 10 7 data streaming mode ................................ ................................ ................................ ................................ .. 15 8 auto tuning implementatio n (ati) ................................ ................................ ................................ ............ 17 9 electrical specifica tions ................................ ................................ ................................ ............................. 20 10 datasheet and part - number information ................................ ................................ .............................. 24 11 revision history ................................ ................................ ................................ ................................ ............ 27 appendix a. memory map ................................ ................................ ................................ ................................ . 28 appendix b. contact information ................................ ................................ ................................ .................. 31
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 3 of 31 all rights reserved revision 1.0 5 october 2015 list of abbreviations ati automatic tuning implementation bp boost power mode cs counts (number of charge transfers) c s internal reference capacitor emi electromagnetic interference esd electro - static discharge ftb/eft (electrical) fast transient bursts gnd ground hc halt charge lp low power mode lta long term average nd noise detect thr threshold
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 4 of 31 all rights reserved revision 1.0 5 october 2015 1 overview the IQS227AS is a single channel capaciti ve proximity and touch controller with an internal voltage regular and reference capacitor (c s ). the iqs 227 a s device s ha ve dedicated pin (s) for the connection of sense electrode s (cx) and output pins for proximity events on pout and touch event on tout. the output pins can be configured for various output methods including a serial data streaming option on tout (1 - wire protocol) or debug i 2 c . device configuration is determined by one time programmable (otp) options. the devices automatically track slow v arying environmental changes via various filters, detect noise and has an a utomatic tuning implementation (ati) to tune the device sense electrode(s) . the iqs227 a s is built on proxsense ? new low voltage platform ideal for battery application (down to 1.8v) . 1.1 applicability all specifications , except where specifically mentioned otherwise, provided by this datasheet are applicable to the following ranges : ? temperature : - 40c to +85c ? supply voltage (v ddhi ) : 1.8v to 3.6v 2 analogue functionality the analog ue circuitry measures the capacitance of a sense electrode attached to the cx pin through a charge transfer process that is periodically ini tiated by the digital circuitry. the measuring process is referred to a conversion and consists of the discharging of reference capacitor and cx, the charging of cx and then a series of charge transfers from cx to c s until a trip voltage is reached. the nu mber of charge transfers required to reach the trip voltage is referred to as the counts (cs). the capacitance measurement circuitry makes use of an internal c s and voltage reference (v ref ). the analog ue circuitry further provides functionality for: ? power on reset (por) detection. ? brown out detection (bod). ? detection of a watch dog timer (wdt)
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 5 of 31 all rights reserved revision 1.0 5 october 2015 3 packaging and pin - out 3.1 iqs 227 a s the iqs227 a s is available in a tsot23 - 6 package. 3.1.1 pin - out figure 3.1 pin - out of iqs 227 a s in tsot23 - 6 package . table 3.1 pin - out descri p tion . iqs 227 as pin name type function 1 tout digital out touch output 2 gnd ground gnd reference 3 pout digital out proximity output 4 v reg analogue output internal regulator pin 5 v ddhi supply input supply voltage input 6 c x analogue i/o sense electrode 1 2 3 t o u t g n d p o u t 6 5 4 c x v d d h i v r e g 2 2 7 a x x
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 6 of 31 all rights reserved revision 1.0 5 october 2015 3.1.2 schematic figure 3.2 typical application schematic of iqs 227 a s . 100pf capacitors are option al for added rf immunity. place all decoupling capacitors (on vddhi and vreg) as close to the ic as possible. refer to azd008 for touch key designs
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 7 of 31 all rights reserved revision 1.0 5 october 2015 4 user configurable options the iqs227 a s provides one time programmable (otp) user options (each option can be modified only once) . the device is fully functional in the default state. otp options are intended for specific applications. the configuration of the device can be done on packaged device s or in - circuit. in - circuit configuration may be limited by values of external components chosen. a number of standard device configurations are available . azoteq can supply pre - configured devices for large quantities. 4.1 configuring of d evice s azoteq offers a configuration tool (ct 2 10 ) and accompanying software (usbprog.exe) that can be used to program the otp user options for pro totyping purposes. more details regarding the configuration of the device with the usbprog program is explained by application note: azd007 C usbprog overview which can be found on the azoteq website . alternat e programming solutions of the iqs227 a s also exist . f or further enquiries regarding this matter please contact azoteq at proxsensesupport@azoteq.com or the local distributor table 4.1 user selectable configuration options : bank 0 ( 0xc4h ) t func p func logic t thr 2 t thr 1 t thr 0 p thr 1 p thr 1 bit 7 bit 0 bank 0: bit 7 t func : touch function section 6.3 0 = normal 1 = toggle bank0: bit 6 p func : proximity function section 6.3 0 = normal 1 = latch bank0: bit 5 logic : i/os output logic select section 6.2 0 = a ctive low 1 = a ctive high bank0: bit 4 - 2 t thr : touch thresholds section 6.5 0 00 = 72 /25 6 001 = 8 /25 6 010 = 24 /25 6 011 = 48 /25 6 100 = 96 /25 6 101 = 128 /25 6 110 = 160 /25 6 111 = 192 /25 6 bank0: bit 1 - 0 p t hr : proximity thresholds section 6.4 0 0 = 4 0 1 = 2 10 = 8 1 1 = 16
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 8 of 31 all rights reserved revision 1.0 5 october 2015 table 4.2 : user selectable configuration options : bank 1 C full ati ( 0xc5h ) t halt1 t halt 0 ~ ~ ~ base 2 base 1 base 0 bit 7 bit 0 bank1: bit 7 - 6 t halt : halt times section 6.13 0 0 = 20 seconds 0 1 = 40 seconds 10 = never 11 = always (prox on 40s) bank1: bit 5 - 3 not used bank1: bit 2 - 0 base : base value section 6.7 000 = 200 001 = 50 010 = 75 011 = 10 0 100 = 150 101 = 25 0 110 = 3 00 111 = 5 00
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 9 of 31 all rights reserved revision 1.0 5 october 2015 table 4.3 user selectable configuration options : bank 1 C partial ati 1 t halt1 t halt 0 m ult sense 1 m ult sense 0 m ult comp 3 m ult comp 2 m ult comp 1 m ult comp 0 bit 7 bit 0 bank 1:7 - 6 t halt : halt times section 6.13 0 0 = 20 seconds 0 1 = 40 seconds 10 = never 11 = always (prox on 40s) bank1: bit 5 - 4 mult : multiplier for sensitivity section 6.8 00 = 1 01 = 2 10 = 3 11 = 4 bank1: bit 3 - 0 mult: multiplier for compensation section 6.8 0000 = 0 1111 = 15 table 4.4 user selectable configuration options : bank 2 ( 0xc6h ) stream trans comms nd target ati lp 1 lp 0 bit 7 bit 0 bank 2 : bit 7 stream : st r eaming method section 7.2 0 = 1 - wire 1 = 2 - wire (i 2 c) bank 2 : bit 6 trans : charge transfer frequency section 6.9 0 = 512khz 1 = 250khz bank 2 : bit 5 comms : streamin g section 7 0 = disabled 1 = enabled bank 2 : bit 4 nd : noise detect section 6.11 0 = disabled 1 = enabled (1 - wire comms only) bank 2: bit 3 target : ati target counts section 6.10 0 = 1 024 1 = 512 bank 2: bit 2 ati : ati selection section 6.12 0 = full 1 = partial bank 2: bit 1 - 0 lp : low power modes section 6.6 0 0 = bp (9ms) 01 = np (128ms) 10 = lp1 (256ms) 11 = lp2 ( 512m s) 1 requires otp bit 2 in bank 2 to be set.
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 10 of 31 all rights reserved revision 1.0 5 october 2015 5 measuring capacitance using the charge t ransfer method the charge transfer method of capacitive sensing is employed on the iqs227 as . (the c harge transfer principle is thoroughly described in the application note: azd004 - azoteq capacitive sensing.) a c harge c ycle is used to take a measurement of the capacitance of the sense electrode (connected to cx ) relative to ground . it consists of a series of pulses charging cx and discharging cx to the reference capacitor, at the charge transfer frequency (fcx - refer to section 9 ). th e number of the pulses required to reach a trip voltage on the reference capacitor is referred to as count value (cs) which is the instantaneous capacitive measurement. the counts ( cs ) are used to determine if either a physical contact or proximity event occurred ( refer to s ection 6.13.1 ) , based on the change in counts ( cs ) detected . the typi cal values of cs , without a touch or proximity condition range between 650 and 1150 counts , although higher and lower count s can be used based on the application requirements . with counts larger than +/ - 1150 the gain of the system may become too high causi ng unsteady operation . the iqs227 a s schedules a charge cycle every t sample seconds to ensure regular samples for processing of results. the duration of the charge cycle is define d as t charge . ( r efer to table 9.5 ) and varies according to the counts required to reach the trip voltage . following the charge cycle other activities such as data streaming is completed (if in streaming mode) , before the next charge cycle is initiated. please note: attaching a probe to the cx pin will increase the capacitance of the sense plate and therefore c s . this may have an immediate influence on the counts (decrease t charge ) and cause a proximity or touch event . after t halt seconds the system will adjust to accommodate for this change . if the total load on cx , with the probe attache d is still lower than the maximum cx load the system will continue to function normally after t halt seconds with the probe attached. figure 5.1 charge cycles as can be seen on cx 6 descriptions of user options th is section describes the individual user programmable options of the iqs227 a s in more detail. user programmable options are programmed to one time programmable (otp) fuse registers ( refer to s ection 4 ). note: ? high =logical 1 and low=logical 0. ? the following sections are explained with pout and tout taken as active low. c x p i n 1 2 3 4 t c h a r g e t s a m p l e
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 11 of 31 all rights reserved revision 1.0 5 october 2015 ? the default is always where bits are set to 0 . refer to s ection 9.3 for the sourcing and sinking capabilities pout and tout. these pins are sourced from v ddhi and will be turn ed high (when active high) for a minimum time of t high , and low for a minimum time of t low (when active low). 6.1 proximity / touch sensor the iqs227 a s provides a proximity output on pout and a touch output on tout , and does not need to be configured . 6.2 logic select for o utput s the logic used by the device can be selected as a ctive high or a ctive low . the output pins , pout and tout , will function based on th is selection . the i/os are push pull in both directions and does not require a pull - up resistor . configuration: bank0 bit 5 logic: output logic select - bit selection 0 active low 1 active high 6.3 output pin function various options for the function of the output pin (s) are available. these are selected as follow: configuration: bank0 bit 7 - 6 func 1 :func 0 output pins functions bit selection 00 pout active, tout active 01 pout latch, tout active 10 pout active, tout toggle 11 pout latch, tout toggle 6.3.1 output function: active with a proximity or touch event , the output pin will change to low and stay low for as long as the event remains (see figure 6.1 ) . also refer to the use of t halt s ection 6.13.1 that may cause the termination of the event. figure 6.1 active mode output configuration 6.3.2 output function: latch (for t latch ) with a proximity or touch event , the output pin will latch low for t latch seconds. when the event terminates prior to t latch the output pin will remain low . when the e vent remains active longer than t latch the output pin will remain low as long as the event remains active ( s ee figure 6.2 ). user actuation output pin 1 0 1 0
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 12 of 31 all rights reserved revision 1.0 5 october 2015 figure 6.2 latch mode output configuration 6.3.3 output function: toggle the output pin will toggle with every proximit y or touch event occurring. thus when an event occurs and the output is low the output will become high and when the output is high the output will become low (s ee figure 6.3 ) . figure 6.3 toggle mode output configuration 6.4 proximity threshold the iqs227 a s has 4 proximity threshold settings. the proximity threshold is selected by the designer to obtain the desired sensitivity and noise immunity. the proximity event is triggered based on the selected proximity threshold; the counts ( cs ) and the lta (long term average) . the threshold is expressed in terms of counts; the same as cs (refer to table 4.3 ) configuration: bank0 bit 1 - 0 p thr 1 :p thr 0 proximity thresholds bit selection 00 4 01 2 (most sensitive) 10 8 11 16 (least sensitive) a proximity event is identified when for at least 6 consecutive samples the following equation holds : p th r = < lta - cs where lt a is the long term average (refer to 6.13.1 ) 6.5 touch threshold the iqs227 a s has 8 touch threshold settings. the touch threshold is selected by the designer to obtain the desired touch sensitivity. the touch threshold is expresse d as a fraction of the lta as follows: ? ??? = ? 256 ? ??? the touch event is triggered based on t th , counts ( cs ) and lta. a touch event is identified when for at least 3 consecutive samples the following equation holds: t th r = < lta - cs with lower average counts (therefore lower lta) values the touch threshold will be lower an d vice versa. t l a t c h + t i m e t h a t u s e r a c t u a t i o n s t a y s a c t i v e o u t p u t p i n 1 0 1 0 u s e r a c t u a t i o n t l a t c h t l a t c h output pin 1 0 1 0 user actuation
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 13 of 31 all rights reserved revision 1.0 5 october 2015 configuration: bank0 bit 4 - 2 t thr 2 :t thr 0 : touch thresholds bit selection 000 72 / 25 6 001 8 /25 6 (most sensitive) 010 24 / 2 5 6 011 48 / 25 6 100 96 / 25 6 101 128 / 25 6 110 160 / 25 6 111 192 / 25 6 (least sensitive) 6.6 power modes the iqs227 a s has four power modes specifically designed to reduce current consumption for battery applications. the power modes are basically implemented around the occurrence of charge cycle every t sample seconds (refer to table 6.1 ) . the fewer charge transfer cycles that need to occur per second the lower the power consumption (but decreased response time) . during boost power mode (bp), charge cycles are initiated approximately every 9 ms . while in any power mode the device will zoom to b p whenever a n existing c oun t sample (cs) indicates a possible proximity or touch event. the device will remain in b p for t zoom seconds and then return to the selected power mode. the zoom function allows reliable detection of events with count s being produced at the b p rate. table 6.1 power mode configuration: bank2 bit1 - 0 bit power mode timing t sample (ms) 00 t b p (default) b p (9ms) 01 t n p 128 10 t lp 1 256 11 t lp 2 512 figure 6.4 lp modes: charge cycles 6.7 base values the sensitivity of the iqs227 a s can be changed by adjusting the base value of the ati algorithm, and as a result changing the compensation required to reach the target. ??????????? = ?????? ???? the target of the iqs227 a s is fixed at 1000 counts. c x z o o m t o b o o s t m o d e a f t e r p r o x i m i t y d e t e c t e d c h a r g e c y c l e d u r a t i o n = t c h a r g e t s a m p l e t s a m p l e
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 14 of 31 all rights reserved revision 1.0 5 october 2015 configuration: bank1 bit2 - 0 base : base value select - bit selection 0 00 200 00 1 50 010 75 011 10 0 100 150 101 25 0 110 3 00 111 5 00 6.8 multipliers when using partial ati, the base value is set up using the multipliers. compensation will still be added automatically to reach the target. 6.9 charge transfer the charge transfer frequency of the iqs227 a s is adjustable. changing the transfer frequency will affect sensitivity and respon se rate. two options are available: configuration: bank 2 bit 6 trans : charge transfer frequency bit selection 0 512khz 1 250khz 6.10 ati target counts the target of the ati algorithm can be adjusted between 1024 (default) and 512 counts. when less sensitivity is required, the lower counts will also increase response rate. configuration: bank2 bit3 target : ati target counts bit selection 0 1024 1 512 6.11 noise detect 6.11.1 nd: rf noise detection the iqs227 a s has rf noise detect (nd) functionality. if nd function is enabled, the iqs227 a s is able to detect rf noise on the tout pin. further details on the working of this can be found in the application notes: azd015 and azd015b. in extremely noise environments, and close proximity to rf noise sources, the noise detect of the iqs227 a s can be enable to block false triggers. proper layout guidelines should always be used before the need to use nd. configuration: bank2 bit4 nd : noise detect bit selection 0 disabled 1 enabled 6.12 enable partial ati in some applications the startup time of the iqs227 a s may be required to be decreased. this is possible by enabling partial ati, if the multipliers required can be determined, and the compensation alone is adequate to account for environmental change. configuration: bank2 bit2 ati : partial ati bit selection 0 disabled 1 enabled 6.13 filter s used by the iqs227 as the iqs227 a s devices employ various signal processing functions that includes the execution of various filters as described below. 6.13.1 long term average (lta) capacitive touch devices detect changes in capacitance that are not always related to the intended proximity or touch of a human. this is a result of changes in the envi ronment of the sense plate and other factors . these changes need to be compensated for in various manners in order to reliably detect touch events and especially to detect proximity events. one mechanism the iqs227 a s employs is the use of a l ong t erm a vera ging filter (iir type filter) which track s slow changes in the environment (expressed as changes in the coun t s ) . the
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 15 of 31 all rights reserved revision 1.0 5 october 2015 result of this filter is a long term average (lta) value that forms a dynamic reference used for various functions such as identification of proximity and touch events . the lta is calculated from the counts (cs). the filter only executes while no proximity or touch event is detected to ensure compensation only for environmental changes. however there may be instances where sudden changes in the environment or changes in the environment while a proximity or touch event has been detected cause the counts to drift away from the lta. to compensate for these situations a halt timer (t halt ) has been defined . the halt timer is started when a proxim ity or touch event occurs and when it expires the lta filter is recalibrated . recalibration causes lta < cs, thus the disappearance of proximity or touch events (refer to 6.4 and 6.5 ). the designer needs to select a halt timer value to best accommodate the required application. configuration: bank1 bit 7 - 6 t halt 1 :t hatl 0 : halt time of long term average bit selection 00 20 seconds 01 40 seconds 10 never 11 always (proximity on 40 seconds) notes: ? the never option indicates that the execution of the filters will never be halted. ? with the always option and the detection of a proximity event the execution of the filter will be halted for only 40 seconds and with the detection of a touch event the execution of the filter will be halted as long as the touch condition applies. refer to application note azd024 - graphical representation of the iir filter for detail regarding the execution of the lta filter. 6.13.2 iir raw data filter the extreme sensitivity of the iqs227 a s makes it susceptible to external noise sources. this causes a decreased signal to noise (s/n) ratio, which could potentially cause false event detections. noise can also couple into the device as a result of poor pcb, sense electrode design and other fact ors influencing capacitive sensing devices. in order to compensate for noise t he iqs227 a s uses an iir filter on the raw data to minimize result of noise in the counts . this filter is implemented on all of the iqs227 a s devices , and cannot be disabled. 7 data streaming mode the iqs227 a s has the capability to stream data to a mcu. this provides the designer with the capability to obtain the parameters within the device in order to aid design into applications. data streaming may further be used by an mcu to control events or further process results obtained from the iqs227 a s devices. data streaming is performed as a 1 - wire data protocol on tout , or set to i 2 c streaming (sda on pout, scl on tout) . data streaming can be enabled as indicated below: configuration: bank 2 bi t7 comms : data streaming bit selection 0 d isabled 1 e nabled configuration: bank 2 bit 5 streaming : d ata streaming mode bit selection 0 1 - wire 1 i 2 c data streaming is initiated by the iqs227 as . when data streaming is enabled data is sent following each charge. figure 7.1 illustrates the communication protocol for initialising and sending data with the 1 wire communication protocol.
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 16 of 31 all rights reserved revision 1.0 5 october 2015 1. communication i s initiated by a start bit . b it defined as a low condition for t start . 2. following the start bit , is a synchronisation byte (t init = 0xaa ) . this byte is used by the mcu for clock synchronisation. 3. following t init the data bytes will be sent . with short data streaming mode enabled, 5 bytes of data will be sent, otherwise 8 bytes will be sent after each charge cycle. 4. each byte sent will be preceded by a start bit and a stop bit will follow every byte. 5. stop bit indicated by taking pin 1 high. the stop bit does not have a defined period . figure 7.1 1 - wire data streaming m ode the following table define s the data streamed from the iqs227 a s devices during the 1 - wire streaming protocol . b 1 b 2 b 3 b 4 b 5 b 6 b 7 b 8 t o u t / o u t t i n i t t s t o p t d a t a s t o p C s t a r t s t o p C s t a r t s t a r t
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 17 of 31 all rights reserved revision 1.0 5 october 2015 table 7.1 byte definitions for 1 - wire data streaming mode byte (b) bit value 0 aa 1 7:0 cs high byte 2 15:8 cs low byte 3 23:16 lta high byte 4 31:24 lta low byte 5 sys flags 39 38 37 36 35 34 33 32 ~ ~ active high filter halt lp active ati busy noise found in zoom 6 47 46 45 44 43 42 41 40 touch proximity multipliers multipliers multipliers multipliers multipliers multipliers 7 55:48 compensation 8 63:56 counter 7.1 event mode the iqs227 a s has event mode implemented during 1 - wire communication. this allows the mcu to monitor the pout pin for status changes (proximity or touch made or released events) instead of capturing data continuously. upon a status change, the iqs227 a s will pull the po ut pin for low to indicate to the mcu to read data. the pout pin will stay low for 1.6ms. 7.2 i 2 c the iqs227 a s also allow for i 2 c streaming for debugging. data streaming can be changed from 1 - wire protocol to i 2 c as shown below : configuration: bank2 bit7: streaming mode bit selection 0 1 - wire protocol 1 i 2 c streaming the memory map for the iqs227 a s can be found in appendix a . the iqs227 a s can communicate on an i 2 c compatible bus structure. note that 4.7k pull - up resistors should be placed on sda and scl. the control byte indicates the 7 - bit device address (0x44h) and the read/write indicator bit. 8 auto tuning implementation (at i) ati is a sophisticated technology implemented in the latest generation proxsense ? devices that optimises the performance of the sensor in a wide range of applications and environmental conditions (refer to application note azd0027 - a uto tuning implemen tation ) . ati makes adjustments through external reference capacitors (as required by most other solutions) to obtain optimum performance . ati adjusts internal circuitry according to two parameters, the ati multiplier and the ati compensation. the ati multiplier can be viewed as a course adjustment and the ati compensation as a fine adjustment. the adjustment of the ati parameters will result in variations in the counts and sensitivity. sensitivity can be observed as the change in current sample as the result of a fixed change in sensed capacitance. the ati parameters have been chosen to provide significant overlap . i t may therefore be possible to select various combinations of ati multiplier and ati compensation settings to obtain the same count value . the sensitivity of the various options may however be different for the same count value .
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 18 of 31 all rights reserved revision 1.0 5 october 2015 8.1 automatic ati the iqs227 a s implements an automatic ati algorithm. this algorithm automatically adjusts the ati parameters to optimise the sensing electrodes connecti on to the device. t he device will execute the ati algorithm whenever the device starts - up and when the counts are not within a predetermined range. while the automatic ati algorithm is in progress this condition will be indicated in the streaming data and proximity and touch events cannot be detected. the device will only briefly remain in this condition and it will be entered only when relatively lar ge shifts in the counts has been detected. the automatic ati function aims to maintain a constant count value , regardless of the capacitance of the sense electrode (within the maximum range of the device). the effects of auto - ati on the application are the following: ? automatic adjustment of the device configuration and processing parameters for a wide range of pcb and application designs to maintain a optimal configuration for proximity and touch detection. ? automatic tuning of the sense electrode at star t - up to optimise the sensitivity of the application. ? automatic re - tuning when the device detects changes in the sensing electrodes capacitance to accommodate a large range of changes in the environment of the application that influences the sensing electro de . ? re - tuning only occurs during device operation when a relatively large sensitivity reduction is detected. this is to ensure smooth operation of the device during operation. ? re - tuning may temporarily influences the normal functioning of the device, but i n most instances the effect will be hardly noticeable. ? shortly after the completion of the re - tuning process the sensitivity of a proximity detec tion may be reduced slightly for a few seconds as internal filters stabilises . auto matic ati can be implemented so effectively due to: ? excellent system signal to noise ratio (snr). ? effective digital signal processing to remove ac and other noise. ? the very stable core of the devices. ? b uilt in capability to accommodate a large range of sensing electrode capacitances . 8.2 iqs227 a s noise immunity the iqs227 a s has advanced immunity to rf noise sources such as gsm cellular telephones, dect, bluetooth and wifi devices. d esign guidelines should however be followed to ensure the best noise immunity. the design of capacitive sensing applications can encompass a large range of situations but as a summary the following should be noted to improve a design: ? a ground plane should be placed under t he ic, except under the cx line . ? all the tracks on the pcb must be kept as short as po ssible. ? the capacitor between v ddhi and gnd as well as between v re g and gnd , must be placed as close as possible to the ic. ? a 100 pf capacitor can be placed in parallel with the 1uf capacitor between v ddhi and gnd . another 100 pf capacitor can be placed i n parallel with the 1uf capacitor between v re g and gnd . ? when the device is too sensitive for a specific application a parasitic capacitor (max 5pf) can be added between the cx line and ground. ? proper sense electrode and button design principles must be fol lowed. ? unintentional coupling of sense electrode to ground and other circuitry must be limited by increasing the distance to these sources or making use of the driven shield. ? in some instances a ground plane some distance from the device and sense electrod e may provide significant shieldin g from undesired interference.
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 19 of 31 all rights reserved revision 1.0 5 october 2015 ? when then the capacitance between the sense electrode and ground becomes t o o large the sensitivity of the device may be influenced.
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 20 of 31 all rights reserved revision 1.0 5 october 2015 9 electrical specifications 9.1 absolute maximum specifications exceeding these maximum specifications may cause damage to the device. operating t emperature - 40c to 85c supply voltage (v ddhi C v ss ) 3.6v maximum pin v oltage ( t out , p out ) v ddhi + 0 . 3v pin voltage ( c x ) 1.7 v minimum pin voltage ( vddhi , vreg , t out , p out , cx ) v ss - 0. 3v minimum p ower - o n s lope 1 0 0v/s hbm esd p rotection ( vddhi , vreg , v ss , t out , p out , cx ) 8 kv 9.2 general characteristics the iqs227 a s devices are rated for supply voltages between 1.8v and 3.6v . table 9.1 iqs 227 a s general operating conditions (self) description conditions parameter min typ max unit supply v oltage v ddhi 1.8 3.6 v internal regulator o utput 1.8 v ddhi 3.6 v reg 1.6 4 1.7 1.7 6 v boost o perating current 1.8 v ddhi 3.6 i iqs227 a s b p 119 12 8 135 a normal o perating curr ent 1.8 v ddhi 3.6 i iqs227 a s n p 4.7 6 7.6 a low power o perating curr ent 1.8 v ddhi 3.6 i iqs227 a s lp 1 2.8 3.5 4.7 a low power o perating curr ent 1.8 v ddhi 3.6 i iqs227 a s lp 2 1.75 < 2 .5 1 3 a charge transfer timings for low power modes are found in section 6.6 . table 9.2 start - up and shut - down slope characteristics description condi tions parameter min max unit por v ddhi slope 100v/s por 1. 5 5 v bod bod 1 v 1 all low power current values arise from characterization done from ( - )35c to (+)85c at 3.3v
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 21 of 31 all rights reserved revision 1.0 5 october 2015 9.3 output characteristics 1 table 9.3 tout characteristics symbol description v oh conditions min typ max unit i source output high voltage 0.9*vddhi v ddhi = 3. 6 v ~ ~ tbd ma 0.9*vddhi v ddhi = 3.3v ~ 10 ~ 0.9*vddhi v ddhi = 1.8 v tbd ~ ~ symbol description v ol conditions min typ max unit i s ink output low voltage 0.1v v ddhi = 3. 6 v tbd ma 0.1v v ddhi = 3. 3 v 1 0 0.1v v ddhi = 1.8 v tbd table 9.4 pout characteristics symbol description v oh conditions min typ max unit i source output high voltage 0.9*vddhi v ddhi = 3.6v ~ ~ tbd ma 0.9*vddhi v ddhi = 3.3v ~ 10 ~ 0.9*vddhi v ddhi = 1.8v tbd ~ ~ symbol description v ol conditions min typ max unit i s ink output low voltage 0.1v v ddhi = 3.6v tbd ma 0.1v v ddhi = 3.3v 10 0.1v v ddhi = 1.8v tbd table 9.5 combined characteristics symbol description v oh conditions min typ max unit i source output high voltage 0.9*vddhi v ddhi = 3.6v ~ ~ tbd ma 0.9*vddhi v ddhi = 3.3v ~ 17 ~ 0.9*vddhi v ddhi = 1.8v tbd ~ ~ symbol description v ol conditions min typ max unit i s ink output low voltage 0.1v v ddhi = 3.6v tbd ma 0.1v v ddhi = 3.3v 20 0.1v v ddhi = 1.8v tbd 1 i/o sink capabilities only in active low configuration. i/o source capabilities only in active high configuration.
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 22 of 31 all rights reserved revision 1.0 5 october 2015 9.4 packaging information figure 9.1 tsot23 - 6 packaging 1 table 9.6 tsot23 - 6 dimensions dimension min max a 2.60mm 3.00mm b 1.50mm 1.70mm c 2.80mm 3.00mm d 0.30mm 0.50mm e 0.95 basic f 0.84mm 1.0 0mm g 0.00mm 0.10mm h 0.30mm 0.50mm i 0 8 j 0.03mm 0.20mm 9.5 package msl moisture sensitivity level (msl) relates to the packaging and handling precautions for some semiconductors. the msl is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (approximately 30c/ 85 %rh see j - std0 33c for more info ) before reflow occur. 1 drawing not on scale d a c e f g h i b j
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 23 of 3 1 all rights reserved revision 1.0 5 october 2015 table 9.7 table 9 - 1 : msl package level (duration ) tsot23 - 6 msl 1 (unlimited at 30 c/85% rh
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 24 of 31 all rights reserved revision 1.0 5 october 2015 10 datasheet and part - number information 10.1 ordering information orders will be subject to a moq (minimum order quantity) of a full reel. contact the official distributor for sample quantities. a list of the distributors can be found under the distributors section of www.azoteq.com . for large orders, azoteq can provide pre - configured devices. the part - number can be generated by using usbprog.exe or the interactive part number generator on the website. ic name iqs 227 a s = self capacitive ic with d ual outputs configuration zzz zzz zz = ic configuration (hexadecimal) package type ts = t so t23 - 6 bulk packaging r = reel (3000pcs/reel) C moq = 3000pcs moq = 1 reel. o rders shipped as full reels i q s 2 2 7 g g z z z z z z z z p p b i c n a m e c o n f i g u r a t i o n b u l k p a c k a g i n g p a c k a g e t y p e
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 25 of 31 all rights reserved revision 1.0 5 october 2015 10.2 device marking C top there are 2 marking versions in circulation for IQS227AS: figure 10.1 first marking variant. figure 10.2 second marking variant. ic name 22 7 a = iqs227 as self capacitive 22 - a = IQS227AS self capacitive batch code xx = aa to zz 10.3 device marking - bottom some batches iqs 2 2 7as will not have any bottom markings. these devices are configured after marking, and may have variations in configuration C please refer to the reel label. other batches will display the configuration set on the chip on the bottom marking. z zz zzz zz configuration 2 2 7 a x x i c n a m e b a t c h c o d e 2 2 - a x x i c n a m e b a t c h c o d e
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 26 of 31 all rights reserved revision 1.0 5 october 2015 10.4 tape & reel specification figure 10.3 tsot23 - 6 tape s pecification.
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 27 of 31 all rights reserved revision 1.0 5 october 2015 11 revision history revision device id 1 package markings description 0 39 28 22 7 a aa IQS227AS self capacitive sensor 1 refers to product number and firmware version
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 28 of 31 all rights reserved revision 1.0 5 october 2015 appendix a. memory map device information [00h] p rod_nr the product number for the iqs227 a s is 39 (decimal). [01h] sw_nr the software version number of the device rom can be read in this byte. the latest software version is 28 (decimal). [10h] sysflags0 bit 7: system_use bit 6: system_use bit 5: logic: logic output indication 0 = active low 1 = active high bit 4: halt: indicates filter halt status 0 = lta not being halted 1 = lta halted bit 3 : lp : low power mode 0 = sample time bp 1 = sample time lp bit 2 : ati : status of automated ati routine 0 = ati is not busy 1 = ati in progress bit 1: nd: this bit indicates the presence of noise interference. 00h product number (prod_nr) bit 7 6 5 4 3 2 1 0 access value 39 (decimal) r note 01h software number (sw_nr) bit 7 6 5 4 3 2 1 0 access value 28 (decimal) r note 10h system flags (sys_flags) bit 7 6 5 4 3 2 1 0 access value ~ ~ logic halt lp ati nd zoom r note
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 29 of 31 all rights reserved revision 1.0 5 october 2015 0 = ic has not detected the presence of noise 1 = ic has detected the presence of noise bit 0: zoom: zoom will indicate full - speed charging once an undebounced proximity is detected. in bp mode, this will not change the charging frequency. 0 = ic not zoomed in 1 = ic detected undebounced proximity and ic is charging at full - speed (bp) [31h] status bit 1: touch: touch indication bit. 0 = no touch detected 1 = touch event detected bit 0: prox: proximity indication bit. 0 = no proximity detected 1 = proximity event detected 31h status bit 7 6 5 4 3 2 1 0 access value touch prox r note 42h counts_hi (cs_h) bit 7 6 5 4 3 2 1 0 access value counts high byte r note 43h counts_low (cs_l) bit 7 6 5 4 3 2 1 0 access value counts low byte r note 83h lta_hi (lta_h) bit 7 6 5 4 3 2 1 0 access value long term average high byte r note 84h lta_low (lta_l) bit 7 6 5 4 3 2 1 0
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 30 of 31 all rights reserved revision 1.0 5 october 2015 [c8h] default comms pointer the value stored in this register will be loaded into the comms pointer at the start of a communication window. for example, if the design only requires the proximity status information each cycle, then the default comms pointer can be set to address 31h . this would mean that at the start of each communication window, the comms pointer would already be set to the proximity status register, simply allowing a read to retrieve the data, without the need of setting up the address. access value long term average low byte r note c4h fuse bank 0 (fb_0) bit 7 6 5 4 3 2 1 0 access value see table 4.1 for more details r note c5h fuse bank 1 (fb_1) bit 7 6 5 4 3 2 1 0 access value see table 4.2 for more details r note c6h fuse bank 2 (fb_2) bit 7 6 5 4 3 2 1 0 access value see table 4.4 for more details r note c7h fuse bank 3 (fb_3) bit 7 6 5 4 3 2 1 0 access value not used r note c8h default_comms_pointer bit 7 6 5 4 3 2 1 0 access value (beginning of device specific data) r/w default 10h
i q switch ? proxsense ? series copyright ? azoteq (pty) ltd 201 5 iqs22 7 as datasheet page 31 of 31 all rights reserved revision 1.0 5 october 2015 appendix b. contact information usa asia south africa physical address 6507 jester blvd bldg 5, suite 510g austin tx 78750 usa rm 2125 , glittery city shennan rd futian district shenzhen, 518033 china 109 main street paarl 7646 south africa postal address 6507 jester blvd bldg 5, suite 510g austin tx 78750 usa rm 2125 , glittery city shennan rd futian district shenzhen, 518033 china po box 3534 paarl 7620 south africa tel +1 512 538 1995 +86 755 8303 5294 ext 808 +27 21 863 0033 fax +1 512 672 8442 +27 21 863 1512 email kobusm@azoteq.com linayu@azoteq.com.cn info@azoteq.com please visit www.azoteq.com for a list of distributors and worldwide representation . the following patents relate to the device or usage of the device: us 6,249,089 b1; us 6,621,225 b2; us 6,650,066 b2; us 6,952,084 b2; us 6,984,9 00 b1; us 7,084,526 b2; us 7,084,531 b2; us 7,265,494 b2; us 7,291,940 b2; us 7,329,970 b2; us 7,336,037 b2; us 7,443,101 b2; us 7,466,040 b2 ; us 7,498,749 b2; us 7,528,508 b2; us 7,755,219 b2; us 7,772,781 b2; us 7,781,980 b2; us 7,915,765 b2; us 7,994,7 26 b2; us 8,035,623 b2; us re43,606 e; us 8,288,952 b2; us 8,395,395 b2; us 8,531,120 b2; us 8 ,659,306 b2; us 8,823,273 b2 ; ep 1 120 018 b2; ep 1 206 168 b1; ep 1 308 913 b1; ep 1 530 178 a1; ep 2 351 220 b1; ep 2 559 164 b1; cn 1330853; cn 1783573; au s 761094; hk 104 1401 iq switch ? , swipeswitch?, proxsense ? , lightsense?, airbutton tm and the logo are trademarks of azoteq. the information in this datasheet is believed to be accurate at the time of publication. azoteq uses reasonable effort to maintain the information up - to - date and accurate, but does not warrant the accuracy, completeness or reliability of the information contained herein. all content and information are provided on a n as is basis only, without any representations or warrant ies, express or implied, of any kind, including representations about the suitability of these products or information for any purpose. a zoteq disclaims all warranties and conditions with regard to these products and information, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non - infringement of any third party intellectual property rights. azoteq assumes no liability for any damages or injury arising from any use of the in formation or the product or caused by, without limitation, failure of performance, error, omission, interruption, defect, delay in operation or transmission, even if azoteq has been advised of the possibility of such damages. the applications mentioned her ein are used solely for the purpose of illustration and azoteq makes no warranty or representation that such applications will be suitable withou t further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. azoteq products are not authorized for use as critical components in life support devic es or systems. no licenses to patents are granted, implicitly, express or implied, by estoppel or otherwise, under any intellectua l property rights. in the event that any of the abovementioned limitations or exclusions does not apply, it is agreed that azoteqs total liability for all losses, damages and causes of action (in contra ct, tort (including without limitation, negligence) or otherwise) will not exceed the amount already paid by the customer for the products. azoteq reserves the right to alter its products, to make co rrections, deletions, modifications, enhancements, improvements and other changes to the content and informa tion, its products, programs and services at any time or to move or discontinue any contents, products, programs or services without prior notification. for the most up - to - date information and binding terms and conditions please refer to www.azoteq.com . www.azoteq.com info@azoteq.com

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