nRF52840 Brownout status

[dmleone]

I am using nRF52840, we have an issue which seems like a standard issue with nordic switching between regular battery and a coin cell backup. 

I need to know the following:

1) with regard to reset voltage levels, when the nordic goes into brownout, is it considered system ON or system OFF mode? because that determines whether i am required to drop voltage to 1.2V or 1.57V. The nordic is always in a system ON mode when going into brownout for my design.

2) When it goes into brownout, what does the system actually do. What status do the GPIO enter. I go from operating at 15uA to 400uA when it enters brownout. So i do not know what the pins are technically doing during this state. I need to know if i can use one of these pins as brownout detect to maybe do something. 

[Kenneth]

Hi,

1. If you don't explicit call the system OFF api in the application to go to system OFF, then the lowest mode is system ON yes.

2. We don't really guarantee any specific operation in a reset state, likely the current will be in several of hundreds of UA, the pins will most likely be in a floating state, no code will be executing.

Kenneth