Disconnect VCC or VSS in a uC based system?

Thread Starter

Chris_Swift

Joined Oct 30, 2019
5
I'm trying to make a circuit board that has a microcontroller on it that performs some communications and sensory... I'd like to be able to turn this entire board on by switching a LOW-side MOSFET (ie, disconnecting ground/vss). The resistance is only 1mOhm (a few mosfets in parallel) in the end so that shouldn't be much of a worry in terms of a higher ground plane compared to my external circuit that communicates with said uController.
I'm debating if it would be smarter to introduce the Nchannel mosfets as a high-side switch using a MAX1614 charge pump.. I'd prefer not to go this route because I don't have much flexibility to change the high-side power traces on the PCB layout to place the 5 mosfets on the high-side (vcc).

Do you think it will be fine to just disconnect GND from the circuit using the mosfets?

Thanks!
-Chris
 

MrChips

Joined Oct 2, 2009
19,376
Welcome to AAC!

What is the supply voltage and current consumption?
What is controlling the power switch?

I have used a high-side PNP transistor for putting circuits into power-down mode.
 

danadak

Joined Mar 10, 2018
3,605
I would say yes to low side pending question on total current
being switched. At 1 mohm thats << than typical run of Cu trace
in the power distribution on a PCB.

Again total current that has to be switched ?

Regards, Dana.
 

Thread Starter

Chris_Swift

Joined Oct 30, 2019
5
Thanks for the replies!

The mosfets may switch up to 100 amps at up to 25.6v.. I have other elements in the circuit to help protect against back emf and such. Normally, only ~10-15 amps will be active during operation of the entire end circuit. I'm just hesitant about the turn on behavior of components given that their ground is cut off, versus their positive side cut off.

The circuit I am referring to is just a small part of that.

But that's why I feel the need to stay with N-channel mosfets, due to the potential high current demands (the PCB is being made to handle these temporary large current demands)
 
Top