STW4102 datasheet(20/34 Pages) STMICROELECTRONICS

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Battery charger

STw4102

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6.7

Watchdog timer

When the fast charge is active, a watchdog timer starts to prevent damage on the battery.

The system controller refreshes the watchdog periodically in order let the charge continue.

When the watchdog time elapses, the charge is stopped.

When the charge starts in trickle mode, to allow the battery to be charged although the

system controller is not running, the watchdog is disabled. However, if for any reason the

charger goes from fast charge mode to trickle mode, then the watchdog is not disabled to

protect against battery failure.

Watchdog timing can be 1 minute, 15 minutes, 30 minutes or 60 minutes. It is programmable

through the I2C interface. The watchdog can be reset by the I2C interface (bit WDOG_RST)

or by unplugging the charger (PWRDETECTN goes to low). The watchdog can also be

enabled and disabled through the I2C interface.

In the standard configuration, the default state at powerup is watchdog enabled and the

timing is one minute.

6.8

Thermal regulation

A thermal regulation circuit limits the charge current in case of high power dissipation due to

high input voltage or high ambient temperature. The charge current is progressively reduced

to maintain the die temperature in a safe area. This allows to charge the battery with the

highest possible current depending on the operating conditions, and protects the device

against any damage.

STW4102 Folha de dados(PDF) 20 Page - STMicroelectronics