Hello,
We found a problem with a device in mass production: nPM1100 doesnt start charging a deeply discharged battery.
Here is detailed information. This device was kept discharged by a customer for long time. But this is not an isolated case, there are more such devices. Voltage on battery leads (VBAT) is 0 V, battery cell voltage is 1.09 V (battery's leads are switched off by the battery's protection module due to under voltage).
After attaching external power to the device (VBUS = 5.0 V) there is a short pulse on VBAT generated by nPM1100:
But charging not started. Pin CHG disabled, pin ERR enabled.
We've tried desoldering C24 and C25, it doesnt help:
Also tried soldering a single 1uF capacitor instead of C24 and C25 as suggested by
but charging not started.
After connecting the battery to a power supply, charging it for little time (the protection module enables voltage on battery's leads) and soldering it back to the device nPM1100 starts charging OK: there is increasing voltage on VBAT, CHG pin enabled, ERR pin disabled.
Here is related schematic:
The battery's characteristics:
And protection module circuit diagram from the battery's datasheet: