Using the STC3100

AN3064

2/15

Doc ID 16263 Rev 1

1

Using the STC3100

1.1

Brief description of the STC3100

The STC3100 battery monitoring function includes the measurement of the battery voltage

and current, measurement of the IC’s die temperature and computation of the battery

charge variation (Coulomb counter). An external sense resistor is used in series with the

battery to adapt the current measurement to the application requirements.

Figure 1 shows a typical application using the STC3100.

Figure 1.

Typical application diagram for the STC3100

The STC3100 mode and operation are controlled through an I²C interface. SCL and SDA

are the clock and data signals of the I²C interface.

1.2

Internal or external 32,768 Hz timebase

The Coulomb counter system needs an accurate 32,768 Hz timebase to compute the level

of charge flowing from and to the battery. The STC3100 can operate from an internal

oscillator or use an external RTC signal for highest accuracy. To use the internal oscillator, a

200 k

Ω 0.1% resistor must be connected to the ROSC pin. The accuracy of the internal

oscillator is 2.5% maximum over the supply voltage and temperature ranges. An external

RTC signal can be applied to the ROSC pin (no resistor required in this case). The signal

must be a square wave with a low level below 0.5 V and a high level above 1.5 V.

GND

SDA

SCL

ROSC

VCC

VIN

CG

IO0

STC3100

Battery

Rcg

uC with

Gas Gauge

firmware

32768 Hz

clock

I2C bus

Battery State-of-charge

Battery data

80 %

Remaining percentage

Remaining time

2:06

0.32 A

Current

3.71 V

Voltage

27 ° C

Temperature

AM04578