STC3100 STMICROELECTRONICS | Alldatasheet
Document overview
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Technical content
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
Applications
■ Cellular phones, PDA, MP3 players, cordless phones ■ Digital cameras, USB appliances, Bluetooth devices
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. The device is programmable through the I2C interface. MiniSO-8 (Plastic micropackage) DFN8 3x3 (Plastic micropackage) 4 5 8IO0 SDA SCL GND VIN ROSC VCC CG Pin connections (top view)
1 Block diagram
Figure 1. STC3100 internal block diagram
2 Pin assignment
Table 1. STC3100 pin description
1 IO0 I/OD General-purpose I/O
3 SDA I/OD I2C serial data
4 SCL I_D I2C serial clock
5 GND Ground Analog and digital ground
6 CG I_A Gas gauge current sense input
7 VCC Supply Power supply
8 VIN I_A Battery voltage sense input
3 Absolute maximum ratings and operating conditions
Table 2. Absolute maximum ratings Table 3. Operating conditions
4 Electrical characteristics
Table 4. Electrical characteristics (2.7 V < V CC < 4.5 V, -20° C to 70° C)
Table 4. Electrical characteristics (2.7 V < V CC < 4.5 V, -20° C to 70° C) (continued)
5 Typical performance curves
Figure 2. Standby current vs. temperature Figure 3. Current measurement accuracy vs. Figure 4. Oscillator frequency accuracy vs. Figure 5. Voltage measurement accuracy vs.
6 Application information
Figure 6. Example of an application schematic using the STC3100 Table 5. External components list
7 Functional description
7.1 Gas gauge
through the I2C control registers. incremented in a 16-bit counter. Figure 7. Gas gauge block diagram
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 2 13 = 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.
STC3100 Functional description
7.5 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.
8 I2C interface
8.1 Read and write operations
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
1110 D e v A DDR2 DevADDR1 DevADDR0 R/W
Table 7. Register address format Table 8. Register data format
8.2 Register map
Table 9. Register map
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 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 monitor functions are in standby. Table 11. REG_CTRL - address 1 counter. GG_RST is a self-clearing bit. conversion cycle. Clears upon reading.
9 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.
9.1 MiniSO-8 package information
Figure 10. MiniSO-8 package mechanical drawing Table 12. Miniso-8 package mechanical data
9.2 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)
Table 14. Order codes
Table 15. Document revision history 27-Jan-2009 1 Initial release.