Intentional over-voltage on nRF52 I/O Pin?

[Krunal Desai]

Hi all --

I have an application where I have a LDO generating 2.6V from a single lithium-ion cell. It has an EN input that I want to expose to the nRF52 with a little RC circuit to allow the nRF52 to trigger its own power-cycle, if desired.

The EN pin on the LDO will be pulled up to the battery rail through a 100kOhm resistor. The nRF would drive a low on this net to cause a cycle to happen. Worst-case, I could source a maximum of 42uA across that resistor into a nRF I/O pin.

Is this enough current (~40uA) to cause permanent damage to the device? I've had other MCUs where with a large resistor, "higher" voltages could be present at the pin due to the large impedance presented.

[Sigurd]

Hi,

Sourcing 42uA should not be any problem. See this thread. But the max input voltage is VDD + 0.3 V.

[Krunal Desai]

Hi Sigurd -- thanks for the quick reply. Is the specification for the maximum continuous current through the Clamping diodes on each I/O cell published?

[Sigurd]

The I/O pin have clamping diodes. We do not provide any details about those in the datasheet, though.

[Krunal Desai]

Thanks -- I ended up tossing a BJT there to interface with the EN pin to sidestep the problem -- BOM adder wasn't too bad for that.