Other Parts Discussed in Thread: BQ25120
I am working on a small USB powered device, we are trying to improve the charge time, but only if the present USB connection allows it. I am setting the input current limit(ILIM) based on the power negotiated over USB. The problem show up if I set the ILIM too low, the charger will continue to charge the battery at a lower rate as expected, but it will also indicate that there is a charge fault, which is not the expected behavior from reading the datasheet.
Procedure
- Set the ICHRG in register 0x03 value to 160 mA
- Set INLIM in register 0x09 value to 100 mA
- Attempt to charge a battery that requires CC charging.
- Battery charging current measures 80-90 mA
- Read register 0x00, it will read 3 which indicates a charger fault
- Read register 0x01, and it will read 0.
So the device is indicating that there is a charging fault, but all of the specific fault bits are set to 0. Further, in table 11 of the user's guide, the actions for VIN_ILIM are "Update charge in progress status, interrupt on INT, input current is limited". It does not mention anything about updating STAT to fault as it does for other entiries.
If I change the ILIM to a higher value, the charging fault will clear up, so this issue is only caused by the ILIM by being too low.
Is there are way to use the ILIM functionality in the bq25120 without it triggering a charging fault?
