Driving input of GPIO P0_27 above the supply voltage

[Ali_1]

Is it OK to drive GPIO P0_27 (when configured as an input, of course) above the supply voltage provided the input current is limited with a series resistor?

In my application, we are using a supply voltage of 3.3V and I am driving P0_27 from a 5V supply via a 3k resistor. In this case, I assume that the internal ESD protection diode of P0_27 will conduct and limit the current flowing into the input and therefore through the ESD diode. I would then expect the voltage at P0_27 to be about 3.3 + 0.6 = 3.9V. Obviously this is above the supply voltage, but since it it current-limited to (5 - 3.9)/3k = 367uA, would that be safe for the nRF52832?

I can increase the value of the series resistor from 3k if needed.

[awneil]

The Absolute Maximum ratings given in the Product Specification tell you the maximum voltage that can be applied to any pin.

[Turbo J]

Ali_1 said:

since it it current-limited to (5 - 3.9)/3k = 367uA, would that be safe for the nRF52832?

Actually: No!

The nRF52832 has operating (read: sleep) modes where the current consumtion is significantly below 300µA. Thus the current flow could raise VCC above the 3.9V absolute maximum limit - damaging the chip.