STBC08 datasheet(10/17 Pages) STMICROELECTRONICS

10 / 17 page

Application information

STBC08

10/17

Application information

The STBC08 uses an internal P-Channel MOSFET to work in constant current and constant

voltage method. It is able to provide up to 800mA with a final regulated output voltage of

4.2V

±1% in full temperature range. No blocking diode and sensing resistor are required. It

is also possible to use an USB port as power supply voltage.

6.1

Charge cycle

A charge cycle begins when the voltage at the VCC pin rises above the UVLO threshold

level, the RPROG program resistor of 1% is connected between the PROG pin to GND pin

and when a battery is connected to the charger output. If the battery voltage is below 2.9V,

the charger enters Trickle Charge mode. In this condition, the device supplies 1/10 of the

programmed charge current to bring the battery voltage up to safe level otherwise the life of

a battery is reduced. If the BAT pin voltage is higher than 2.9V the charger enters in

Constant Current Mode. When the BAT pin voltage is close to the final float voltage (4.2V)

the device enters in Constant Voltage Mode and the charge current begins to decrease. The

charge cycle is terminated when the current drops to 1/10 of the programmed value.

6.2

VCC Pin

Input Supply Voltage. This pin is used to supplie the device in the range from 4.25V to 6.5V

voltage. A bypass capacitor of 1µF is recommended for use. When VCC value drops of

30mV of the BAT pin voltage, the device enters in Shutdown Mode, dropping IBAT to less

than 2µA.

6.3

Power ON pin

The POWER ON pin is an open drain flag that indicates VCC presence, VUVLO<VCC<7.2V

and VCC>VBAT. While in high impedance indicates that VCC< VUVLO, VCC>7.2V or

VCC<VBAT. In high impedance status the VCC is insufficient to start the charge cycle.

6.4

CHRG pin

The CHRG pin is an open drain flag, it indicates the status of the charge. When the pin is in

low state, the device is charging the battery. If the pin is in high impedance state the charge

is terminated.

Table 5 describes Flag Status values for the CHRG pin.

Table 5.

CHRG

LOW

HIGH

Power-ON

LOW

HIGH

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