I recently got the NPM1100 dev kit and it's awesome.
I'm working on a portable bluetooth device based on NRF52840, which has NPM1100 as battery management IC.
I would like to implement a functionality that turns off/on the device by enabling or disabling the NPM1100. As far as I know this would be possible using the ship mode pins since they
can be controlled by a digital input for enabling and disabling power delivery to the NRF. The issue is when connecting the USB, it automatically turns on the device (VOUTB is 3.10V). I want the device to keep in ship mode unless SHPHLD is activated. Is there a way to avoid USB activating it?
Many LDOs have an EN pin to activate the regulator, however NPM1100 has none. We are using the LTC2955 IC as a controller for pushbutton off/on.
The current setup is the following:
- Setup 1: The LTC2955 receives ON signal from pushbutton, and activates high EN (output from LTC2955) pin connected to a mosfet. The mosfet has input from VOUTB and is controlled by EN from LTC2955, it acts as the main power switch for the NRF52840. When using this setup I can measure 65nA when mosfet is activated.
- Setup 2: The LTC2955 drives the SHPLD and SHPACT pins. In this case I measure 20microA. (USB will ruin functionality :/)
For now we have setup 1 implemented. Is there a more "practical way" to do this, instead of a mosfet? Maybe a 3v LDO (which has ENABLE pin) connected to VOUTB as input? Measurements are taken with PPK2.
Thanks
