Other Parts Discussed in Thread: BQ25750,
Tool/software:
Hi,
We designed a PCB using the BQ25750 charger IC (similar to the BQ25750EVM) to charge a 4S1P LiFePO₄ battery. The charging current is set to 1.8A, and the full charge voltage is 14.6V.
Issue:
- The battery is not charging properly.
- Charging current is very low (only 8–25 mA).
- Output voltage at battery terminal 12.85V (same as battery voltage when the battery is connected).
- Output voltage at battery terminal 7.05V (when the battery is not connected).
- No change in voltage or current even after 15 minutes.
- STAT1 is ON, STAT2 is OFF (indicating charging in progress) when the battery is connected.
- No changes made to default register settings.
Setup:
- Battery voltage during testing: 12.85V
- Input voltage (VIN): 12V
- ICHG set as: 1.8A
- ILIMIT set as: 10A
- Actual load during this testing: < 0.5A
- Buck boost Fsw: 250kHz
- Driver: Internal LDO
- CE pin: LOW (charger enabled)
Please help us identify and fix the issue.
Thank you