POR

watchdog timer expired

Reset registers

I2C interface enabled

I2C Write?

Host Mode

Start watchdog timer

Host programs registers

Y

N

Default Mode

Reset watchdog timer

Reset registers

Reset REG01

bit[6]?

Y

N

Watchdog Timer

Expired?

I2C Write?

Y

N

Y

N

bq24195

bq24195L

www.ti.com

SLUSB97 – OCTOBER 2012

Figure 22. Watchdog Timer Flow Chart

Plug in USB100mA Source with Good Battery

When the input source is detected as 100mA USB host, and the battery voltage is above batgood threshold

If the charger device is in host mode, it will stay in HIZ state even after the USB100mA source is removed, and

the adapter plugs in. During the HIZ state, REG00[7] is set HIGH and the system load is supplied from battery. It

is recommended that the processor host always checks if the charger IC is in HIZ state when it wakes up. The

host can write REG00[7] to 0 to exit HIZ state.

If the charger is in default mode, when the DC source is removed, the charger device will get out of HIZ state

automatically. When the input source plugs in again, the charger IC runs detection on the input source and

update the input current limit.

USB Timer when Charging from USB100mA Source

The total charging time in default mode from USB100mA source is limited by a 45-min max timer. At the end of

the timer, the device stops the converter and goes to HIZ.

Status Outputs (STAT and INT)

Charging Status Indicator (STAT)

The bq24195L, bq24195 indicates charging state on the open drain STAT pin. The STAT pin can drive LED as

the application diagram shows.

Copyright © 2012, Texas Instruments Incorporated

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