nRF52840 in System OFF mode

RE: nRF52840 in System OFF mode

bojan — Wed, 23 Aug 2023 09:42:33 GMT

Understood.

Thanks for the additional explanations.

I'm closing this ticket...

Cheers 🍻

RE: nRF52840 in System OFF mode

Stian Røed Hafskjold — Wed, 23 Aug 2023 09:40:27 GMT

Thanks, that is good to hear. The DK has two main power domains, VDD which is powered from the USB, and VDD_nRF (P22) which is powering the nRF chip only.

The reason VDD has to be powered as well is that the analog switch ICs which are isolating the nRF52 from the rest of the circuitry (cutting off SWD lines, etc) is powered from this domain. So if these switches are floating, you can get some leakage current.

Best regards,
Stian

RE: nRF52840 in System OFF mode

bojan — Wed, 23 Aug 2023 06:48:04 GMT

Thanks for the explanations, Stian Røed Hafskjold.

After plugging in the USB cable, I was able to measure ~0.85uA in System OFF mode:

I guess this is more or less in accordance with the numbers in a datasheet.

Would you be so kind to briefly explain why it was needed to use 5V power supply from USB in order to get the realistic numbers of current consumption?

Thanks for your support.

Cheers,
Bojan.

RE: nRF52840 in System OFF mode

Stian Røed Hafskjold — Tue, 22 Aug 2023 13:47:59 GMT

Hi, I think you just need to plug in the USB cable and you should be good. (assuming you connect it exactly like in the picture you posted, which does not have the USB connected)

Here is how I connect the DK:

And here is the idle current measurement, running the beacon sample:

2.2uA

Here is the hex file if you want to check:

devzone.nordicsemi.com/.../3286.nrf52840_5F00_xxaa.hex

Best regards,
Stian