I am using an NPM 1300 with nRF Connect SDK 3.2.4. I am using a 2.8 mAH LiPol battery. I have the termination voltage set at 4.2 volts and the charging current set at 100 mA. On several units, as the charging process nears full, the PMIC charging mode will transition directly from constant current to trickle charge and toggle back and forth. When I read the PMIC registers, its toggling between those states as well. The termination voltage reads 4.165. I have a power profiler set up as the charger at 5 volts. The VBus value is 4.6 volts. I can sample the current from the power profiler and see it toggling between 100 and down to like 0-10 mA. If I change the charging current down to like 32, it will then stay in constant current mode at the appropriate charge level. If I continue to ramp it up, it will eventually start failing as I described above.
According to the NPM 1300 flow chart, the device should transition to constant voltage before transitioning into trickle charge. I have seen this process occur correctly on some devices, but doesn't occur correctly on just as many devices. We've tried ramping up the termination voltage thinking that maybe the charging current is causing a voltage drop and briefly reaching the termination voltage but that didn't help and also wouldn't explain why its going directly to trickle charge.
Also on the power profiler, I can see massive amounts of current being drawn before it transitions to 0-10 mA and enters trickle charge mode. After exactly 100 ms, it comes out of trickle charge mode and appears to reenter constant current mode but then about 850 ms later, current starts surging between 100 and 250 mA again and then it repeats this cycle.
