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| 19-3774; Rev 4; 5/09 Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages General Description The MAX6775-MAX6781 low-power, 1%-accurate battery monitors are available in the ultra-small DFN package (1.0mm x 1.5mm) and SC70 packages. These low-power devices are ideal for monitoring single lithium-ion (Li+) cells, or multicell alkaline/NiCd/NiMH power sources. These devices offer single (MAX6775/ MAX6776/MAX6777/MAX6778) or dual (MAX6779/ MAX6780/MAX6781) low-battery outputs and feature fixed or resistor-adjustable hysteresis. Hysteresis eliminates the output chatter sometimes associated with battery voltage monitors, usually due to input-voltage noise or battery terminal voltage recovery after load removal. These devices are available in several versions: with single- or dual-voltage monitors, and with fixed or adjustable hysteresis. The MAX6775/MAX6776 offer a single battery monitor and factory-set hysteresis of 0.5%, 5%, or 10%. The MAX6779/MAX6780/MAX6781 have two battery monitors in a single package and factory-set hysteresis of 0.5%, 5%, or 10%. The MAX6777/ MAX6778 offer a single battery monitor with external inputs for the rising and falling thresholds, allowing external hysteresis control. For convenient interface with system power circuitry or microprocessors, both open-drain and push-pull outputs are available. The single-channel devices are available with open-drain or push-pull outputs. The dual-channel devices are available with both outputs open-drain, both outputs push-pull, or one of each (see the Selector Guide). This family of devices is offered in small 5-pin SC70 and ultra-small 6-pin DFN packages, and is fully specified over the -40C to +85C extended temperature range. o o o o o Features o 1.0%-Accurate Threshold Specified Over Temperature Single/Dual, Low-Battery Output Options Low 3A Battery Current Open-Drain or Push-Pull Low-Battery Outputs Fixed or Adjustable Hysteresis Low-Input Leakage Current Allows Use of Large Resistors o Guaranteed Valid Low-Battery-Output Logic State Down to VBATT = 1V o Immune to Short Battery Transients o Fully Specified from -40C to +85C o Small 5-Pin SC70 or Ultra-Small 6-Pin DFN (1mm x 1.5mm) Package MAX6775-MAX6781 Ordering Information PART MAX6775XK_+T MAX6775LT_+T MAX6776XK_+T MAX6776LT_+T MAX6777XK+T MAX6777LT+T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 5 SC70 6 DFN 5 SC70 6 DFN 5 SC70 6 DFN Ordering Information continued at end of data sheet. +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. MAX6775/MAX6776/MAX6779/MAX6780/MAX6781 are available with factory-trimmed hysteresis. Specify trim by replacing "_" with "A" for 0.5%, "B" for 5%, or "C" for 10% hysteresis. Applications Battery-Powered Systems (Single-Cell Li+ or Multicell NiMH, NiCd, Alkaline) Cell Phones/Cordless Phones Pagers Portable Medical Devices PDAs Electronic Toys MP3 Players 3.6V Typical Operating Circuit BATT MAX6775 LBI LBO IN DC-DC CONVERTER SHDN OUT Pin Configurations appear at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781 ABSOLUTE MAXIMUM RATINGS BATT to GND............................................................-0.3V to +6V LBI, LBL, LBH, LBI1, LBI2 to GND ...............-0.3V to minimum of ((VBATT + 0.3V) and +6V) LBO, LBO1, LBO2 to GND (open-drain) .................-0.3V to +6V LBO, LBO1, LBO2 to GND (push-pull).........-0.3V to minimum of ((VBATT + 0.3V) and +6V) Input Current (all pins) ........................................................20mA Output Current (all pins) .....................................................20mA Continuous Power Dissipation (TA = +70C) 5-Pin SC70 (derate 3.1mW/C above +70C) ..............247mW 6-Pin DFN (derate 2.1mWC above +70C) ..............168mW Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C 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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1) PARAMETER Operating Voltage Range (Note 2) Supply Current SYMBOL VBATT IQ CONDITIONS TA = 0C to +70C TA = -40C to +85C VBATT = 3.7V, no load VBATT = 1.8V, no load 0.5% hysteresis version LBI, LBI_ Falling Threshold (Note 3) LBI Rising Threshold LBI Input Leakage Current LBL, LBH Threshold LBL, LBH Input Leakage Current VLBIF VLBIR 0.2V VLBI VBATT - 0.2V VBATT = 1.8V to 5.5V VBATT - 0.2V VLBL/LBH 0.2V 5% hysteresis version 10% hysteresis version 1.2037 1.1493 1.0888 1.2098 -5 1.2098 -5 1.222 MIN 1.0 1.2 4 3.2 1.2159 1.1609 1.0998 1.222 TYP MAX 5.5 5.5 7 6 1.2280 1.1725 1.1108 1.2342 +5 1.2342 +5 V nA V nA V UNITS V A FIXED HYSTERESIS (MAX6775/MAX6776/MAX6779/MAX6780/MAX6781) ADJUSTABLE HYSTERESIS (MAX6777/MAX6778) 2 _______________________________________________________________________________________ Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages ELECTRICAL CHARACTERISTICS (continued) (VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1) PARAMETER Propagation Delay Startup Time Output Low (Push-Pull or Open-Drain) VOL SYMBOL tPD CONDITIONS VLBI_ + 100mV to VLBI_ - 100mV VBATT rising above 1.6V VBATT 1.2V, ISINK = 100A VBATT 2.7V, ISINK = 1.2mA VBATT 4.5V, ISINK = 3.2mA VBATT 1.6V, ISOURCE = 100A Output High (Push-Pull ) VOH VBATT 2.7V, ISOURCE = 500A VBATT 4.5V, ISOURCE = 800A Output Leakage Current (Open-Drain) Output not asserted, VLBO_ = 5.5V 0.8 x VBATT 0.8 x VBATT 0.8 x VBATT -100 +100 nA V MIN TYP 9 3 0.3 0.3 0.3 V MAX UNITS s ms LOW-BATTERY OUTPUTS (LBO, LBO1, LBO2) MAX6775-MAX6781 Note 1: Devices are tested at TA = +25C and guaranteed by design for TA = TMIN to TMAX, as specified. Note 2: Operating range ensures low-battery output is in the correct state. Minimum battery voltage for electrical specification is 1.6V. Note 3: The rising threshold is guaranteed to be higher than the falling threshold. Typical Operating Characteristics (TA = +25C, unless otherwise noted.) MAXIMUM TRANSIENT DURATION vs. THRESHOLD OVERDRIVE MAX6775 toc02 SUPPLY CURRENT vs. TEMPERATURE MAX6775 toc01 PROPAGATION DELAY vs. TEMPERATURE 12 VBATT = 1.6V PROPAGATION DELAY (s) 11 70 MAXIMUM TRANSIENT DURATION (s) 60 50 40 30 20 10 0 85 1 OUTPUT ASSERTED ABOVE THIS LINE 5.5 SUPPLY CURRENT (A) 5.0 4.5 4.0 3.5 3.0 2.5 -40 -15 10 35 60 VBATT = 2.4V VBATT = 1.6V VBATT = 5V VBATT = 3.6V VBATT = 3V 10 VBATT = 5V 9 8 100mV OVERDRIVE 85 7 -40 -15 10 35 60 10 100 1000 TEMPERATURE (C) TEMPERATURE (C) THRESHOLD OVERDRIVE VTH - VCC (mV) _______________________________________________________________________________________ MAX6775 toc03 6.0 3 Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781 Typical Operating Characteristics (continued) (TA = +25C, unless otherwise noted.) NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE, MAX67__A MAX6775 toc04 NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE, MAX67__B MAX6775 toc05 NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE, MAX67__C NORMALIZED AT TA = +25C MAX6775 toc06 1 0 THRESHOLD VOLTAGE (mV) NORMALIZED AT TA = +25C 1 NORMALIZED AT TA = +25C 1 THRESHOLD VOLTAGE (mV) RISING -1 FALLING -2 -3 -4 -5 -40 -15 10 35 60 85 TEMPERATURE (C) RISING FALLING THRESHOLD VOLTAGE (mV) 0 0 FALLING RISING -1 -1 -2 -3 -2 -4 -40 -15 10 35 60 85 TEMPERATURE (C) -3 -40 -15 10 35 60 85 TEMPERATURE (C) LBO OUTPUT VOLTAGE vs. SINK CURRENT MAX6775 toc07 LBO OUTPUT VOLTAGE vs. SOURCE CURRENT 5.0 4.5 OUTPUT VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 VBATT = 1.8V VBATT = 3.3V MAX6775 toc08 0.5 VBATT = 1.8V 0.4 OUTPUT VOLTAGE (V) VBATT = 3.3V 5.5 VBATT = 5.0V 0.3 0.2 VBATT = 5.0V 0.1 0 0 3 6 9 12 15 SINK CURRENT (mA) 1.0 0 1 2 3 4 5 SOURCE CURRENT (mA) 4 _______________________________________________________________________________________ Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages Pin Description MAX6775/ MAX6776 DFN 1 2 3 SC70 1 2 3 MAX6777/ MAX6778 DFN -- 2 -- SC70 -- 2 -- MAX6779/ MAX6780/ MAX6781 DFN -- 2 -- GND2 GND LBI Reserved. Must be connected to GND. Do not use as the only GND connection. Ground Low-Battery Input. Connect to the resistive divider to set the trip level. Low-Battery Output, Active-Low. When VLBI/VLBL falls below the falling threshold, LBO asserts. LBO deasserts when VLBI/VLBH exceeds the rising threshold voltage. No Connection. Not internally connected. Battery Input. Power supply to the device. Rising-Trip-Level Input. Connect to a resistive divider to set the rising trip level. Falling-Trip-Level Input. Connect to a resistive divider to set the falling trip level. Low-Battery Input 2. Connect to a resistive divider to set the trip level. Low-Battery Input 1. Connect to a resistive divider to set the trip level. Low-Battery Output 1, Active-Low. When VLBI1 falls below the falling threshold voltage, LBO1 asserts. LBO1 deasserts when VLBI1 exceeds the rising threshold voltage. LBO1 is push-pull on the MAX6779/MAX6781 and open-drain for the MAX6780. Low-Battery Output 2, Active-Low. When VLBI2 falls below the falling threshold voltage, LBO2 asserts. LBO2 deasserts when VLBI2 exceeds the rising threshold voltage. LBO2 is open-drain for the MAX6780/MAX6781 and push-pull for the MAX6779. MAX6775-MAX6781 NAME FUNCTION 4 5 6 -- -- -- -- 4 -- 5 -- -- -- -- 4 5 6 1 3 -- -- 4 -- 5 1 3 -- -- -- -- 6 -- -- 1 3 LBO N.C. BATT LBH LBL LBI2 LBI1 -- -- -- -- 4 LBO1 -- -- -- -- 5 LBO2 _______________________________________________________________________________________ 5 Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781 Detailed Description These battery monitors have an active-low output that asserts when the input falls below a set voltage. They also offer hysteresis for noise immunity, and to remove the possibility of output chatter due to battery terminal voltage recovery after load removal. They are available with one or two monitors per package, with push-pull or open-drain outputs, and with internally set or externally adjustable hysteresis (dual-channel devices offer only internally fixed hysteresis). Figures 1, 2, and 3 show block diagrams and typical connections. See the Selector Guide for details. VBATT BATT LBI1 MAX6779 MAX6780 MAX6781 1 HYSTERESIS CONTROL LBO1 Low-Battery Output All devices are offered with either push-pull or opendrain outputs (see the Selector Guide). The MAX6781 has one push-pull output and one open-drain output, configured as in Table 1. On all devices with open-drain outputs an external pullup resistor is required. The open-drain pullup resistor can connect to an external voltage up to +6V, regardless of the voltage at BATT. 0 VREF 0 LBO2 LBI2 1 GND Table 1. MAX6781 Outputs DEVICE MAX6781 LBO1 Push-Pull LBO2 Open-Drain Figure 2. Dual-Channel Fixed-Hysteresis Block Diagram VBATT BATT RH MAX6775 MAX6776 LBI RL HYSTERESIS CONTROL 1 LBO VBATT BATT RH MAX6777 MAX6778 LBL RHYST LBH 0 VREF GND RL VREF GND 0 LBO 1 Figure 1. Single-Channel Fixed-Hysteresis Block Diagram Figure 3. Single-Channel Adjustable-Hysteresis Block Diagram 6 _______________________________________________________________________________________ Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages The MAX6779, MAX6780, and MAX6781 monitor two battery levels or two independent voltages. A common application for this type of dual-battery monitor is to use one output as an early warning signal and the other as a dead-battery indicator. Hysteresis Input hysteresis defines two thresholds, separated by a small voltage (the hysteresis voltage), configured so the output asserts when the input falls below the falling threshold, and deasserts only when the input rises above the rising threshold. Figure 4 shows this graphically. Hysteresis removes, or greatly reduces, the possibility of the output changing state in response to noise or battery terminal voltage recovery after load removal. Adjustable Hysteresis The MAX6777/MAX6778 offer external hysteresis control through the resistive divider that monitors battery voltage. Figure 3 shows the connections for external hysteresis. See the Calculating an External Hysteresis Resistive Divider section for more information. MAX6775-MAX6781 Applications Information Resistor-Value Selection Choosing the proper external resistors is a balance between accuracy and power use. The input to the voltage monitor, while high impedance, draws a small current, and that current travels through the resistive divider, introducing error. If extremely high resistor values are used, this current introduces significant error. With extremely low resistor values, the error becomes negligible, but the resistive divider draws more power from the battery than necessary and shortens battery life. Figure 1 calculates the optimum value for RH using: RH = eA x VBATT IL Fixed Hysteresis The MAX6775/MAX6776/MAX6779/MAX6780/MAX6781 have factory-set hysteresis for ease of use, and reduce component count. For these devices, the absolute hysteresis voltage is a percentage of the internally generated reference. The amount depends on the device option. "A" devices have 0.5% hysteresis, "B" devices have 5% hysteresis, and "C" devices have 10% hysteresis. Table 2 presents the threshold voltages for devices with internally fixed hysteresis. VBATT VLBIR MAX6775 MAX6776 where eA is the maximum acceptable absolute resistive divider error (use 0.01 for 1%), VBATT is the battery voltage at which LBO should activate, and IL is the worstcase LBI leakage current. For example, with 0.5% accuracy, a 2.8V battery minimum, and 5nA leakage, RH = 2.80M. Calculate RL using: RL = - VHYST VLBIF VLBIF x RH VLBIF - VBATT tPD LBO tPD where VLBIF is the falling threshold voltage from Table 2. Continuing the above example, select VLBIF = 1.0998V (10% hysteresis device) and RL = 1.81M. Figure 4. Hysteresis Table 2. Typical Falling and Rising Thresholds for MAX6775/MAX6776/MAX6779/MAX6780/MAX6781 DEVICE OPTION A B C PERCENT HYSTERESIS (%) 0.5 5 10 FALLING THRESHOLD (VLBIF) (V) 1.2159 1.1609 1.0998 RISING THRESHOLD (VLBIR) (V) 1.222 1.222 1.222 HYSTERESIS VOLTAGE (VHYST) (mV) 6.11 61.1 122 _______________________________________________________________________________________ 7 Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781 Calculating an External Hysteresis Resistive Divider Setting the hysteresis externally requires three external resistors, as shown in Figure 3. Select RH using the following formula: RH eA x VBATT _ RISING IL and finally, calculate RHYST: RHYST = RLO - RL Monitoring a Battery Voltage Higher Than the Allowable VBATT For monitoring higher voltages, supply power to BATT that is within the specified supply range, and power the input resistive divider from the high voltage to be monitored. Do not exceed the Absolute Maximum Ratings. where eA is the allowable error due to input leakage current (typically 0.005 or less), VBATT_RISING is the desired rising threshold, and IL is the worst-case leakage current (5nA). Then calculate RLO (which is the sum of RL and RHYST): RLO = VLBI x RH VBATT _ FALLING - VLBI Adding External Capacitance to Reduce Noise and Transients If monitoring voltages in a noisy environment, add a bypass capacitor of 0.1F from BATT to GND as close as possible to the device. For systems with large transients, additional capacitance may be required. A small capacitor (<1nF) from LBI_ to GND may provide additional noise immunity. where VLBI is 1.222V and VBATT_FALLING is the desired falling threshold. Calculate RL using: RL = VLBI x (RH + RLO ) VBATT _ RISING Selector Guide PART MAX6775XK_+T MAX6775LT_+T MAX6776XK_+T MAX6776LT_+T MAX6777XK+T MAX6777LT+T MAX6778XK+T MAX6778LT+T MAX6779LT_+T MAX6780LT_+T MAX6781LT_+T LBO OUTPUT Single Single Single Single Single Single Single Single Dual Dual Dual OUTPUT TYPE Push-Pull Push-Pull Open-Drain Open-Drain Push-Pull Push-Pull Open-Drain Open-Drain Push-Pull Open-Drain Mixed HYSTERESIS Fixed Fixed Fixed Fixed Adjustable Adjustable Adjustable Adjustable Fixed Fixed Fixed PIN-PACKAGE 5 SC70 6 DFN 5 SC70 6 DFN 5 SC70 6 DFN 5 SC70 6 DFN 6 DFN 6 DFN 6 DFN 8 _______________________________________________________________________________________ Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages Top Marks PART MAX6775XKA+T MAX6775XKB+T MAX6775XKC+T MAX6775LTA+T MAX6775LTB+T MAX6775LTC+T MAX6776XKA+T MAX6776XKB+T MAX6776XKC+T MAX6776LTA+T MAX6776LTB+T MAX6776LTC+T TOP MARK ASA ASB ASC BU BW BX ASJ ASK ASL BY BZ CA PART MAX6777XK+T MAX6777LT+T MAX6778XK+T MAX6778LT+T MAX6779LTA+T MAX6779LTB+T MAX6779LTC+T MAX6780LTA+T MAX6780LTB+T MAX6780LTC+T MAX6781LTA+T MAX6781LTB+T MAX6781LTC+T TOP MARK ASD CB ASI CC BL BM BN BO BP BQ BR BS BT MAX6775-MAX6781 Ordering Information (continued) PART MAX6778XK+T MAX6778LT+T MAX6779LT_+T MAX6780LT_+T MAX6781LT_+T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 5 SC70 6 DFN 6 DFN 6 DFN 6 DFN Chip Information PROCESS: BICMOS +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. MAX6775/MAX6776/MAX6779/MAX6780/MAX6781 are available with factory-trimmed hysteresis. Specify trim by replacing "_" with "A" for 0.5%, "B" for 5%, or "C" for 10% hysteresis. _______________________________________________________________________________________ 9 Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages MAX6775-MAX6781 Pin Configurations TOP VIEW BATT N.C. 5 LBO 4 + GND2 1 5 BATT 6 GND 2 MAX6775 MAX6776 4 LBO 1 MAX6775 MAX6776 2 GND 3 LBI LBI 3 SC70 GND2 DFN BATT N.C. 5 LBO 4 BATT 6 LBO2 5 LBO1 4 + LBH 1 5 BATT 6 GND 2 MAX6777 MAX6778 4 LBO 1 MAX6777 MAX6778 2 GND 3 LBL 1 LBI2 MAX6779 MAX6780 MAX6781 2 GND 3 LBI1 LBL 3 SC70 LBH DFN DFN Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 5 SC70 6 DFN PACKAGE CODE X5-1 L611-1 DOCUMENT NO. 21-0076 21-0147 10 ______________________________________________________________________________________ Low-Power, 1%-Accurate Battery Monitors in DFN and SC70 Packages Revision History REVISION NUMBER 4 REVISION DATE 5/09 DESCRIPTION Updated Calculating an External Hysteresis Resistive Divider section PAGES CHANGED 8 MAX6775-MAX6781 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 (c) 2009 Maxim Integrated Products Heaney Maxim is a registered trademark of Maxim Integrated Products, Inc. |
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