GPIO Power looping back to Vcc

RE: GPIO Power looping back to Vcc

ketiljo — Mon, 01 Oct 2018 12:21:22 GMT

It's the ESD protection diodes that causes this. When the voltage on a GPIO pin is VDD + 0.3 V, they start to conduct and will lift VDD and power the device. This is why the max voltage on any pin is VDD + 0.3 V

So make sure you don't exceed this limit at any time.

RE: GPIO Power looping back to Vcc

bhargav i — Mon, 01 Oct 2018 10:14:22 GMT

At the end, we must power up the device first before connectiong GPIO lines from PC?

RE: GPIO Power looping back to Vcc

awneil — Mon, 01 Oct 2018 10:11:09 GMT

Make sure there are no reverse current paths; eg, using switches or blocking diodes, and/or enduring signals are in the correct states before powering down ...

RE: GPIO Power looping back to Vcc

bhargav i — Mon, 01 Oct 2018 10:09:01 GMT

Then how generally this issue would be addressed?

RE: GPIO Power looping back to Vcc

awneil — Mon, 01 Oct 2018 10:03:41 GMT

What else do you have connected to the board?

Yes, it is common that powered-up external peripherals can feed power back to an unpowered part - nothing specifically to do with Nordic.

When designing systems in which parts can be powered-down, while other parts remain powered-up, this is always an area that requires careful attention...!