Hello,
We have recently integrated the BQ25672 into a design and we are experiencing trouble with charging.
The design is based on a 2S battery configuration. We are using either 9V or 12V to charge. The system is connected to a host processor, but we are finding that there are issues with or without the host active.
The trouble is that the system will not charge.
During our investigation we have found a series of odd things occur:
1. We have seen the VBUS_OVP_STAT and VBAT_OVP_STAT flags go high.
2. We have seen the HIZ-Mode bit turn on, and refuse to turn off unless we remove all power. We have even tried using the I2C host to write the bit, but still cannot get the battery to charge.
3. We have sometimes had luck plugging in a 9V adapter, when a 12V adapter wouldn't work. But over time we are finding that even the 9V adapter stops working.
4. We have sometimes had luck with removing all power, then plugging in the battery, then plugging in the power supply. However, if you unplug and plug the power supply in, eventually it will stop working.
Out of 4 prototypes that all worked to begin with, only 1 is now working, and I am skeptical that it will continue to work. The rest of them no longer work, even when attempting the above tricks.
When reviewing the registers, the IC is aware that there is power present, through a "unknown 3A adapter" and that the power is good. So from what I can tell, the system should charge, but it won't.
I've seen notes in the forum about the need for the TVS on the battery and a snubber on the power input, but am wondering if that is required for a 2S configuration with a 9V / 12V power supply.
Below is my schematic, the host system is not shown, but I'm hoping that it isn't an important factor. Even when the host is held in reset, we are still unable to charge.
Any assistance you can give me would be greatly appreciated.
Thanks,
Jason
