nRF52840 DK: Powering SoC with 1V8 while keeping board connected through USB

[afarre]

Hello,

I need to power the nRF52840 with 1.8V while keeping it connected to SES through USB.

I believe I have to proceed as directed at User Guide paragraph 8.3.5 “nFR52840 SoC direct supply”, but I need to keep it connected (flashing and logging) through USB.

I am not sure if it is a safe setup, because while nRF52840 works at 1.8V it is to communicate with Interface MCU (ATSAM3U2CA-AU) at 3.0V level, which exceeds the nRF52840 spec limits.

Please let me know if it is a safe setup or it should be done some other way.

Thank you

[Kenneth]

See here: https://devzone.nordicsemi.com/f/nordic-q-a/59679/using-the-nrf52840-dk-with-1-8v-io

Kenneth

[afarre]

Thank you for the answer and sorry about I wasn't abe to find a similar post.

But I have to say it answers only partially may question by repeating what is said at User Gude:
"Please try the following setup: SW10 set to ON. USB connected to J2. SW9 set to VDD. P21 powered from an external 1.8V supply. SW6 set to default."

But I am also asking if doing that, NRF52840 is to be powered with 1.8V while it is to communicate with Intereface MCU at 3.0V. nRF52840 datasheet says at "Absolute maximum ratings" that max Vi/O is VDD+0.3. That means 2.1V when powered at 1.8V.

In brief, it seem that proposal does not meet nRF52840 spec.