Analog Integrated Circuit Device Data



Freescale Semiconductor

20

BC3770

5.3.10.1 Charger Enable Control

The CHGEN bit in the control register and CHGENB pin are used to enable or disable the charging process.

Figure 8. Charger Enable

If the CHGENB pin is not used in the application, leave the pin float since CHGENB has an internal 300 k

 pull-down resistance to ground.

5.3.10.2 Battery Presence Detection

The BC3770 monitors battery presence via the NOBAT pin in any condition. This function utilizes the pull-down resistor on VF in the

battery pack. If no battery is detected, the charging is suspended immediately and the corresponding interrupt event is reported to the

processor via the INTB pin. If the NOBAT pin needs to be connected to an ADC input on the main processor, a resistor-divided

configuration in fig should be done to lower the voltage rating to 1.8 V.

Figure 9. Resister Divided Network

If NOBAT is not used as a battery presence indicator, the following configuration is also possible.

Figure 10. Resister Divided Network Option

CH GENB

300 k

Charger

Enabled

I2C bit ,

CHGEN=1

1-Cell

Li-Ion

Battery

+

VF/ID

-

NOBAT

ADC Input

SM5418

100k?

100k?

around 1.6V

if no battery

attached

BC3770

100 k



100 k



1-Cell

Li-Ion

Battery

+

VF/ID

-

NOBAT

ADC Input

100k?

or

other

value

SM5418

IO_1V8

BC3770

100 k



or

Other

Value