Brief disconnection of battery leads to NPM1100 stay in shutdown state

[peterqu94305]

Hello

We have design a system with NRF52840, NPM1100 and LIR2032 battery.  The NPM1100 generates 3.0V and charge the battery.  We have discovered that NPM1100 enter and stay in shutdown state after a brief disconnection and reconnection of the battery.

How to reproduce:

1. NPM1100-CAAA generates 3.0V, VSUB is disconnected, LIR2032 is charged, a button to exit ship mode.
2. Briefly disconnect the battery (~100 milliseconds)
3. Reconnect the battery

Symptom:

1. 3.0V output is 0.
2. Pressing the button to exit ship mode/wake up does not work.
3. If connect VUSB, then NPM1100 powers up and MCU boot up.

Can the Nordic team review this and check if there are any vulnerability in the power up sequence, battery detection sequence or brown-out reset sequence state machine that could lead to corner case where the NPM1100 stays in shutdown mode?

Thank you,

[Susheel Nuguru]

What does brief disconnect mean? can you please show some power sniff logs on the input pin to see if the powerdown and powerup during that brief disconnect was as expected?