STC3100 Battery monitor IC with Coulomb counter/gas gauge Features ■ Battery voltage monitoring ■ Internal temperature sensor ■ Coulomb counter with 12/14-bit AD converter, +/- 80 mV input voltage range ■ Internal or external 32768 Hz time base ■ I2C interface for gas gauge monitoring and device control ■ 32-RAM bytes ■ 8-byte unique device ID ■ One general-purpose I/O MiniSO-8 (Plastic micropackage) DFN8 3x3 (Plastic micropackage) Applications ■ Cellular phones, PDA, MP3 players, cordless phones ■ Digital cameras, USB appliances, Bluetooth devices Pin connections (top view) IO0 ROSC SDA SCL Description The STC3100 monitors the critical parameters of a single-cell Li-Ion battery (voltage, temperature and current) and includes hardware functions to implement a gas gauge for battery charge monitoring, based on a programmable 12- to 14-bit A/D converter. With a typical 30 milliOhms external sense resistor, the battery current can be up to 2.5 A and the accumulator system provides a capacity up to +/-7000 mAh with a resolution of 0.2 mAh. 1 2 8 3 7 6 4 5 VIN VCC CG GND The device is programmable through the I2C interface. January 2009 Rev 1 1/21 www.st.com 21 Block diagram 1 STC3100 Block diagram Figure 1. STC3100 internal block diagram 1.2 V reference VCC 32 kHz time base AD converter 11 bits (unsigned) Accumulators and control registers General-purpose I/O line SDA ROSC Temp sensor MUX VIN CG+ AD converter 12 / 14 bits (signed) SCL Oscillator CG CG- IO0 I2C interface RAM & ID registers GND AM00830 2/21 STC3100 2 Pin assignment Pin assignment Table 1. Note: STC3100 pin description Pin # Pin name Type Function 1 IO0 I/OD General-purpose I/O 2 ROSC I_AD Oscillator bias resistor or external 32 kHz clock for gas gauge 3 SDA I/OD I2C serial data 4 SCL I_D I2C serial clock 5 GND Ground 6 CG I_A 7 VCC Supply 8 VIN I_A Analog and digital ground Gas gauge current sense input Power supply Battery voltage sense input I: input O: output OD: open drain A: analog D: digital 3/21 Absolute maximum ratings and operating conditions 3 Absolute maximum ratings and operating conditions Table 2. Absolute maximum ratings Symbol Vmax Parameter Maximum voltage on any pin Vio Voltage on I/O pins Tstg Storage temperature Tj ESD Table 3. Maximum junction temperature Electrostatic discharge (HBM human body model) Value Unit 7 V -0.3 to 7 V -55 to 150 °C 150 °C 2 kV Value Unit Operating conditions Symbol 4/21 STC3100 Parameter Vcc Operating supply voltage on VCC 2.7 to 5.5 V Vin Input voltage on Vin 0 to Vcc V 2.0 V -40 to 85 °C Vmin Minimum voltage on VCC for RAM content retention Toper Operating free air temperature range STC3100 Electrical characteristics 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 100 uA Supply ICC Operating current consumption Average value over 4s Istby Current consumption in standby standby mode, inputs=0V 2 uA Ipdn Current consumption in power down VCC < UVLOth, inputs=0V 1 uA 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 Gas gauge A/D converter Vin_gg Input voltage range -80 Iin Input current for CG pin ADC_res AD converter granularity 12 bits 13 bits 14 bits ADC_offset AD converter offset CG = 0V 12 bits 13 bits 14 bits ADC_time AD conversion time (32768Hz clock) 12 bits 13 bits 14 bits ADC_acc AD converter gain accuracy at full scale 25° C over temperature range Fosc Internal time base frequency Rosc = 200 kΩ, 0.1% Osc_acc Internal time base accuracy 25° C, VCC = 3.6 V over temperature and voltage ranges Fosc_ext External time base frequency range Cur_res Current register LSB value Chg_res Charge register LSB value (32,768 Hz clock) =Cur_res*2^12*0.5/3600 Global_ CG_acc Gas gauge accuracy (not including the external sense resistor tolerance) Using internal time base Using external time base +80 mV 500 nA 47.08 23.54 11.77 -2 -2 -3 uV uV uV 2 2 3 125 250 500 ms ms ms 0.5 1 32768 30 LSB LSB LSB % % Hz 2 % 2.5 % 70 kHz 11.77 uV 6.70 uV.h 3.5 1 % % 5/21 Electrical characteristics Table 4. STC3100 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 and temperature a/d converter Vin_adc Input voltage range Vcc = 5 V LSB LSB value Voltage measurement Temperature measurement ADC_time AD conversion time (32,768 Hz clock) Volt_acc Battery voltage measurement accuracy 2.7 V<Vin<4.5 V, VCC=Vin Temp_acc Internal temperature sensor accuracy 0 2.44 0.125 mV °C 250 ms -0.5 +0.5 % -3 +3 °C Digital I/O pins (SCL, SDA, IO0) Vih Input logic high Vil Input logic low Vol Output logic low (SDA, IO0) 6/21 1.2 Iol = 4 mA V 0.35 V 0.4 V STC3100 Typical performance curves 5 Typical performance curves Figure 2. Standby current vs. temperature Figure 3. 1.6 1.4 Current measurement accuracy vs. temperature 0.6 Vcc=4.5V Vgg=80mV 0.4 1.0 ADC_acc (%) Istby (uA) 1.2 0.8 0.6 0.2 0.0 -0.2 0.4 -0.4 0.2 0.0 -50 -25 0 25 50 75 100 -0.6 -50 125 -25 0 Temp (°C) Figure 4. 25 50 75 100 125 Temp (°C) Oscillator frequency accuracy vs. temperature Figure 5. 2.0 Voltage measurement accuracy vs. temperature 0.6 Vin=3.5V 1.5 0.4 Volt_acc (%) Osc_acc (%) 1.0 0.5 0.0 -0.5 0.2 0.0 -0.2 -1.0 -0.4 -1.5 -2.0 -50 -0.6 -25 0 25 50 Temp (°C) 75 100 125 -50 -25 0 25 50 75 100 125 Temp (°C) 7/21 Application information 6 STC3100 Application information Figure 6. Example of an application schematic using the STC3100 Optional filter Rosc ROSC VCC C1 IO voltage R1 VIN C2 STC3100 SCL SDA CG Rcg GND IO0 AM00831 Table 5. 8/21 External components list Name Value Tolerance Comments Rcg 10 to 50 mΩ 1% Rosc 200 kΩ 0.1% C1 1 µF C2 220 nF Battery voltage input filter (optional) R1 1 kΩ Battery voltage input filter (optional) Gas gauge sense resistor Internal oscillator bias resistor Supply decoupling capacitor STC3100 Functional description 7 Functional description 7.1 Gas gauge The gas gauge is used to monitor the available battery capacity. The voltage drop across the external sense resistor is integrated during a conversion period and input to a 12- to 14-bit AD converter. The output conversion is accumulated into a 28-bit accumulator. The system controller can control the gas gauge and read the data (upper 16 bits of the accumulator) through the I2C control registers. The AD converter output is in two’s complement format. When a conversion cycle is completed, the result is added to the charge accumulator and the number of conversions is incremented in a 16-bit counter. Figure 7. Gas gauge block diagram 16-bit counter 16 Counter register 16 Current register 16 28 Charge register 28-bit accumulator CG GND 16 12/14-bit AD converter 3 28 EOC cg_rst 2 cg_res cg_clock cg_enable rd_req Control logic cg_calibration 32768 Hz Control registers AM00832 The controller can read the value of the most recent conversion in two’s complement format by reading the REG_CURRENT registers. These registers are updated at the end of each conversion. The differential inputs are scaled to the full range of the AD converter, introducing a small offset error. A high value written to the CG_CAL bit of the control register connects the inputs of the AD converter together, allowing the controller to measure the digital offset error. Using this measurement, one can calibrate the gas gauge and reduce errors due to the internal offset error. 9/21 Functional description STC3100 The conversion cycle for n bit resolution is 2n clock cycles. Using the 32,768 Hz internal clock, the conversion cycle time is 125 to 500 ms for a 12- to 14-bit resolution. The LSB value is set by the internal gain and internal reference and is 11.77 uV at maximum resolutions. When using an external 30 milliOhms sense resistor, the 28-bit accumulator results in a capacity of approximately +/- 7300 mA.h. The upper 16 bits of the accumulator can be read from the I2C interface, giving a resolution of 0.2 mA.h. When the battery voltage falls below the under voltage lockout threshold at 2.7 V, the gas gauge system is stopped and the STC3100 stays in standby mode with minimum quiescent current. All registers are maintained down to 2.0 V. Below 2.0 V, the registers are reset to their default power-on value. The gas gauge system needs an accurate 32,768 Hz timebase to compute the level of charge flowing from/to the battery. The STC3100 can operate from an internal oscillator, or use an external RTC signal for highest accuracy. 7.2 Battery voltage and temperature monitoring The battery voltage and chip temperature (close to the battery temperature) are measured by means of an A/D converter and a multiplexer. This function takes place concurrently to the gas gauge function with a dedicated A/D converter, which means that it does not affect the performance of the gas gauge. To reduce the power consumption, a conversion takes place only every two seconds, alternatively for battery voltage and temperature (so each value is refreshed every four seconds). The conversion cycle takes 213 = 8192 clock cycles. Using the 32,768 Hz internal clock, the conversion cycle time is 250 ms. The resolution is 2.44 mV for the battery voltage and 0.125° C for the temperature. 7.3 General-purpose input/output A general-purpose I/O line is available. The output is an open drain, and an external pull-up resistor may be needed in the application. Writing the IO0DATA bit to 0 forces the IO0 output low; writing the IO0DATA bit to 1 leaves the IO0 output in a high impedance state. Reading the IO0DATA bit gives the state of the IO0 pin. In standby (CG_RUN=0), reset (PORDET set to 1) and power-down (Vcc<UVLOth) states, the IO0 output is open and the input is read as zero whatever is the actual state of the IO0 pin. 7.4 RAM registers The STC3100 provides 32 RAM registers to store any information regarding battery status, charge cycles, battery aging, proprietary informations, etc... The register content is maintained during standby and low voltage states, down to the power-on reset level of approximately 2.0 V. Below this level, the content is not preserved. This usually means that the Li-Ion cell was very deeply discharged and has been damaged. 10/21 STC3100 7.5 Functional description Unique device ID The STC3100 provides a means to identify the battery pack or the subsystem. Each device has its own unique 8-byte ID made of an 8-bit part ID (value = 10h for the STC3100), a 48-bit random unique ID and an 8-bit CRC. The CRC-8 is calculated according to bytes REG_ID0 to REG_ID6 using the "x8 + x2 + x + 1" polynomial with a zero initial value. Since the device ID is downloaded from the ROM at power-up and is subsequently kept in read-only RAM locations together with the general-purpose RAM registers, the device ID can also be used as an indicator of the RAM integrity. 11/21 I2C interface STC3100 8 I2C interface 8.1 Read and write operations The interface is used to control and read the current accumulator and registers. It is compatible with the Philips I2C registered trademark (version 2.1). It is a slave serial interface with a serial data line (SDA) and a serial clock line (SCL). ● SCL: input clock used to shift data. ● SDA: input/output bidirectional data transfers. A filter rejects the potential spikes on the bus data line to preserve data integrity. The bidirectional data line supports transfers up to 400 kbit/s (fast mode). The data is shifted to and from the chip on the SDA line, MSB first. The first bit must be high (START) followed by the device address and read/write bit control. Bits DevADDR0 to DevADDR2 are factory-programmable, the default device address value being 70h (AddrID0 = AddrID1 = AddrID2 = 0). The STC3100 then sends an acknowledge at the end of an 8-bit long sequence. The next 8 bits correspond to the register address followed by another acknowledge. The data field is the last 8-bit long sequence sent, followed by a last acknowledge. Table 6. Device address format b7 b6 b5 b4 b3 b2 b1 b0 1 1 1 0 DevADDR2 DevADDR1 DevADDR0 R/W Table 7. Register address format b7 b6 b5 b4 b3 b2 b1 b0 RegADDR7 RegADDR6 RegADDR5 RegADDR4 RegADDR3 RegADDR2 RegADDR1 RegADDR0 Table 8. Register data format b7 b6 b5 b4 b3 b2 b1 b0 DATA7 DATA6 DATA5 DATA4 DATA3 DATA2 DATA1 DATA0 12/21 STC3100 Figure 8. I2C interface Read operation Slave Master Start Device addr 7 bits W A Reg address 8 bits A Restart Device addr 7 bits R A Reg data 8 bits A Reg data 8 bits A A Stop Address n+2 Address n+1 Start bit = SDA falling when SCL = 1 Stop bit = SDA rising when SCL = 1 Restart bit = start after a start Acknowledge = SDA forced low during a SCL clock Reg data 8 bits AM00833 Figure 9. Write operation Start Device addr 7 bits W A Reg address 8 bits Start bit = SDA falling when SCL = 1 Stop bit = SDA rising when SCL = 1 Restart bit = start after a start A Reg data 8 bits A Reg data A 8 bits Address n+1 Reg data 8 bits A Stop Address n+2 AM00834 13/21 I2C interface 8.2 STC3100 Register map The register space provides 12 control registers, 8 read-only (factory OTP) registers for unique device ID and 32 read/write general-purpose RAM registers. Mapping of all registers is shown in Table 9. Detailed descriptions of registers 0 (REG_MODE) and 1 (REG_CTRL) are shown in Table 10 and Table 11. All registers are reset to default values at power-on or reset, and the PORDET bit in register REG_CTRL is used to indicate the occurrence of a power-on reset. Table 9. Register map Name Control registers Type Description 0 to 23 REG_MODE 0 R/W Mode register REG_CTRL 1 R/W Control and status register REG_CHARGE_LOW 2 R Gas gauge charge data, bits 0-7 REG_CHARGE_HIGH 3 R Gas gauge charge data, bits 8-15 REG_COUNTER_LOW 4 R Number of conversions, bits 0-7 REG_COUNTER_HIGH 5 R Number of conversions, bits 8-15 REG_CURRENT_LOW 6 R Battery current value, bits 0-7 REG_CURRENT_HIGH 7 R Battery current value, bits 8-15 REG_VOLTAGE_LOW 8 R Battery voltage value, bits 0-7 REG_VOLTAGE_HIGH 9 R Battery voltage value, bits 8-15 REG_TEMPERATURE_LOW 10 R Temperature value, bits 0-7 REG_TEMPERATURE_HIGH 11 R Temperature value, bits 8-15 Device ID registers 24 to 31 REG_ID0 24 R Part type ID = 10h REG_ID1 25 R Unique part ID, bits 0-7 REG_ID2 26 R Unique part ID, bits 8-15 REG_ID3 27 R Unique part ID, bits 16-23 REG_ID4 28 R Unique part ID, bits 24-31 REG_ID5 29 R Unique part ID, bits 32-39 REG_ID6 30 R Unique part ID, bits 40-47 REG_ID7 31 R Device ID CRC RAM registers 14/21 Address (decimal) 32 to 63 REG_RAM0 32 ... ... REG_RAM31 63 R/W General-purpose RAM register 0 ... R/W General-purpose RAM register 31 STC3100 I2C interface Values held in consecutive registers (such as the charge value in the REG_CHARGE_LOW and REG_CHARGE_HIGH registers) must be read with a single I2C access to ensure data integrity. It is possible to read multiple values in one I2C access, all values will be consistent. The charge data is coded in 2’s complement format, and the LSB value is 6.70 uV.h. The battery current is coded in 2’s complement format, and the LSB value is 11.77 uV. In 13-bit resolution mode, the 0 bit is always set to zero. In 12-bit resolution, bits 0 and 1 are always set to zero. The battery voltage is coded in binary format, and the LSB value is 2.44 mV. The temperature value is coded in 2’s complement format, and the LSB value is 0.125° C. The temperature of 0° C corresponds to code 0. Table 10. REG_MODE - address 0 Name Pos. Type Def. 0 R/W 0 32,768 Hz clock source: 0: auto-detect, 1: external clock GG_RES [2,1] R/W 00 Gas gauge ADC resolution: 00:14 bits, 01:13 bits, 10:12 bits GG_CAL 3 R/W 0 0: no effect 1: used to calibrate the AD converters 0 0: standby mode. Accumulator and counter registers are frozen, gas gauge and battery monitor functions are in standby. 1: operating mode. SEL_EXT_CLK GG_RUN 4 R/W [7..5] Table 11. Name IO0DATA Description Unused REG_CTRL - address 1 Pos. Type Def. Description R X Port IO0 data status: 0 = IO0 input is low, 1 = IO0 input is high W 1 Port IO0 data output drive: 0 = IO0 output is driven low,1 = IO0 output is open 0 GG_RST 1 W 0 0: no effect 1: resets the charge accumulator and conversion counter. GG_RST is a self-clearing bit. GG_EOC 2 R 1 Set at the end of a battery current conversion cycle. Clears upon reading. VTM_EOC 3 R 1 Set at the end of a battery voltage or temperature conversion cycle. Clears upon reading. R 1 Power on reset (POR) detection bit: 0 = no POR event occurred, 1 = POR event occurred 0 Soft reset: 0 = release the soft-reset and clear the POR detection bit, 1 = assert the soft-reset and set the POR detection bit. PORDET 4 W [7..5] Unused 15/21 Package information 9 STC3100 Package information In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. 16/21 STC3100 9.1 Package information MiniSO-8 package information Figure 10. MiniSO-8 package mechanical drawing Table 12. Miniso-8 package mechanical data Dimensions Ref. Millimeters Min. Typ. Inches Max. Min. Typ. Max. A 1.10 0.043 A1 0.15 0.006 A2 0.75 b 0.95 0.030 0.22 0.40 0.009 0.016 c 0.08 0.23 0.003 0.009 D 2.80 3.00 3.20 0.110 0.118 0.126 E 4.65 4.90 5.15 0.183 0.193 0.203 E1 2.80 3.00 3.10 0.110 0.118 0.122 e L 0.85 0.65 0.40 0.60 0.033 0.026 0.80 0.016 0.024 L1 0.95 0.037 L2 0.25 0.010 k ccc 0 0.037 0.031 8 0.10 0.004 17/21 Package information 9.2 STC3100 DFN8 package information Figure 11. DFN8 3x3x1.0 mm package mechanical drawing (pitch 0.5 mm) Table 13. DFN8 3x3x1.0 mm package mechanical data (pitch 0.5 mm) Dimensions Ref. A Millimeters Min. Typ. Max. Min. Typ. Max. 0.80 0.90 1.00 0.031 0.035 0.039 0.02 0.05 0.0008 0.0019 0.65 0.80 0.025 0.031 A1 A2 0.55 A3 0.021 0.20 0.008 b 0.18 0.25 0.30 0.007 0.010 0.012 D 2.85 3.00 3.15 0.112 0.118 0.124 D2 2.20 2.70 0.087 E 2.85 3.15 0.112 E2 1.40 1.75 0.055 e L ddd 18/21 Inches 3.00 0.50 0.30 0.40 0.106 0.118 0.124 0.069 0.020 0.50 0.08 0.012 0.016 0.020 0.003 STC3100 10 Ordering information Ordering information Table 14. Order codes Part number Temperature range STC3100IST Package Marking Tape & reel O201 MiniSO-8 -40°C, +85°C STC3100IQT Packing DFN8 3 x 3 19/21 Revision history 11 STC3100 Revision history Table 15. 20/21 Document revision history Date Revision 27-Jan-2009 1 Changes Initial release. STC3100 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. 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