STC3105IQT

STC3105 Battery monitor IC with alarm output for gas gauge applications Features ■ 0.5% accuracy battery voltage monitoring ■ Low battery alarm output with programmable thresholds ■ Low power: 60 µA in power-saving mode, 2 µA max in standby mode ■ Ideal for implementation of robust gas gauge systems using open-circuit voltage and coulomb counter methods ■ Small 3x2 mm package TDFN8 3x2 (Plastic micropackage) Applications ■ Mobile phones, multimedia players, digital cameras ■ Portable medical equipment Description The STC3105 battery monitor includes the hardware functions required to implement a lowcost gas gauge for battery monitoring. The STC3105 uses accurate measurements of the battery voltage to estimate a battery’s state-ofcharge (SOC). It uses a low cost sense resistor to precisely sense the charge or discharge states, detect light-load conditions without ambiguity for voltage measurements, and accurate SOC calculation. The coulomb counter method is used for SOC tracking in high-load conditions. Pin connections (top view) ALM SDA SCL GND 1 2 8 3 7 6 4 5 VIN VCC NC CG An alarm output signals a low SOC condition, and can also indicate low battery voltage. The alarm threshold levels are programmable. The device is programmable through an I2C interface. September 2011 Doc ID 022198 Rev 1 1/23 www.st.com 23 Contents STC3105 Contents 1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7 8 6.1 Battery monitoring functions and operating modes . . . . . . . . . . . . . . . . . 10 6.2 Battery voltage monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.3 Current sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.4 Coulomb counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.5 Alarm output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.6 Battery voltage relaxation timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.7 Timing diagram in run mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 I2C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1 Read and write operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.2 Register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1 TDFN8 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 9 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2/23 Doc ID 022198 Rev 1 STC3105 1 Block diagram Block diagram Figure 1. STC3105 internal block diagram 6 REFERENCE 6## !CCUMULATORSAND CONTROLREGISTERS (Z TIMEBASE /SCILLATOR 6). !$CONVERTER -58 #' #' #' 3#, 3$! !,- !LARMOUTPUT  ) #INTERFACE 2!-)$REGISTERS '.$ '!0-3-$ Doc ID 022198 Rev 1 3/23 Pin assignment 2 STC3105 Pin assignment Table 1. Note: 4/23 STC3105 pin description Pin Pin name Type Function 1 ALM I/OD Alarm signal output, open drain, external pull-up resistor is required 2 SDA I/OD I2C serial data 3 SCL I_D I2C serial clock 4 GND Ground 5 CG I_A 6 NC 7 VCC Supply 8 VIN I_A Analog and digital ground Current sensing input Reserved test pin. Do not connect. Power supply Battery voltage sensing input I: input O: output OD: open drain A: analog D: digital Doc ID 022198 Rev 1 STC3105 3 Absolute maximum ratings and operating conditions Absolute maximum ratings and operating conditions Table 2. Absolute maximum ratings Symbol VCCMAX VIO TSTG TJ ESD Table 3. Symbol Parameter Maximum voltage on VCC pin Voltage on I/O pins Storage temperature Maximum junction temperature Electrostatic discharge (HBM: human body model) Unit 7 V -0.3 to 7 V -55 to 150 °C 150 °C 2 kV Value Unit 2.7 to 5.5 V 2.0 V -40 to 85 °C Operating conditions Parameter VCC Operating supply voltage on VCC VMIN Minimum voltage on VCC for RAM content retention TOPER Value Operating free air temperature range Doc ID 022198 Rev 1 5/23 Electrical characteristics STC3105 4 Electrical characteristics Table 4. Electrical characteristics (2.7 V < VCC < 4.5 V, -20 ° C to 70 ° C) Symbol Parameter Conditions Min Typ Max Units 60 - 70 100 µA µA Supply ICC Operating current consumption Average value over 4 s in: – power-saving mode – Active mode ISTBY Current consumption in standby Standby mode, inputs=0V 2 µA IPDN Current consumption in power-down VCC < UVLOTH, inputs=0V 1 µA UVLOTH Undervoltage threshold (VCC decreasing) 2.7 V UVLOHYST Undervoltage threshold hysteresis POR Power-on reset threshold 2.5 (VCC decreasing) 2.6 100 mV 2.0 V Current sensing Vin_gg Input voltage range IIN Input current for CG pin ADC_res AD converter granularity ADC_offset AD converter offset ADC_time AD conversion time 500 ADC_acc AD converter gain accuracy at full scale 25 ° C (using external sense resistor) Over temperature range 0.5 - FOSC Internal time base frequency Osc_acc Internal time base accuracy Cur_res Current register LSB value Chg_res Charge register LSB value 6/23 -80 +80 mV 500 nA 11.77 CG = 0 V 25 ° C, VCC = 3.6 V over temperature and voltage ranges =Cur_res*2^12*0.5/3600 Doc ID 022198 Rev 1 -3 µV 3 LSB ms 1 % % 32768 Hz 2 % 2.5 % 11.77 µV 6.70 µVh STC3105 Table 4. Electrical characteristics Electrical characteristics (2.7 V < VCC < 4.5 V, -20 ° C to 70 ° C) (continued) Symbol Parameter Conditions Min Typ Max Units 5 V Battery voltage measurement Vin_adc Input voltage range 0 LSB LSB value 2.44 mV ADC_time AD conversion time 250 ms Volt_acc Battery voltage measurement accuracy 2.7 V