Tool/software:
I have used this charger on a multiple other packs to charge a 3s 3p LiFePO pack. The circuit design is very similar to the datasheet shown below:
Only one pack seems to have this problem, but replacing the charger IC multiple times has not fixed the issue so any help would be appreciated.
The problem is that when the adapter is plugged in (15V) the chargers ACDRV line does not change (Datasheet says it should change by 6V). The voltage it sits at is just enough to keep the gate of Q2 open enough to allow small currents to go through and short the power supply directly to the battery pack through Q3. Since there is less than 0.5V difference between SRN and VCC due to the power supply shorting, the charger remains in a sleep state and does not close the gate of Q3. On a good pack the ACDRV line changes as expected and will switch between 15V (Pulled up) and 9V(Gate open), but on this pack it just wants to sit at about 13V. Any help would be appreciated, at this point I am just stumped and confused. Additional information is that when I disconnect the battery cells and let SRN be pulled to GND, applying 15V allows startup like normal, then adding the cells back in the circuit, the charger works like normal since the IC is out of its sleep state. (SRN and VCC has a larger difference than 0.5V)
Thanks,
