ACE4054

Fully integrated constant current/constant voltage

Li-ion battery charger

VER 1.4

15

To detect the charge statues of the ACE4054, connect a microprocessor and force the digital output pin

(OUT) high and measure the voltage at the CHRG pin, as shown in Figure4.

The N-channel MOSFET will pull the pin voltage low even with the 2K pull-up resistor. Once the charge

cycle terminates, the N-channel MOSFET is turned off and a 20

μA current source is connected to the

CHRG pin. The IN pin will then be pulled high by the 2K pull-up resistor. To determine if there is a weak

pull-down current, the OUT pin should be forced to a high impedance state. The weak current source will

pull the IN pin low through the 820K resistor; if CHRG is high impedance, the IN pin will be pulled high,

indicating that the part is in a UVLO state.