nRF52840 working with 5V

[Aeolipyle]

Hi,

I've got a question regarding voltage compatibility.   The nRF52840 will be driving many LEDs.   Would it be possible to use a separate 5V supply with the LEDs and use the GPIO pins of the nRF52840 as a pseudo pull down?   My concern here would be causing harm to the nRF52840 and/or possibly forward biasing ESD diodes.  

David 

P.S. Below is a schematic illustrating the idea and question whether it's safe to run the  nRF52840 using a 5v supply for an LED.   This assumes the nRF52840 runs off of 3.3 volts. 

[Mojo]

As long the different potential voltage at the LED, when the P0.05 is at logic 1, is lower than the forward voltage of the LED.  Otherwise your LED will always be on. 

[Andreas]

Hi,

 

As mentioned by Mojo you need to note the forward voltage. Another potential concern is what happens during switch on and off, if the voltage on the pin exceeds 3.6V you risk damaging the IO or ESD circuitry as this exceeds the maximum ratings for the IC.

 

Best regards,

Andreas