NRF52840 too high power consumption

[jonas.woerner]

Hi,

I know that this issue is well documented in the forum, but I have read everything and tried all of the suggested fixes, but nothing worked.

I am trying to Enter systemOFF mode and wake up from an external signal later.

when I enter systemOFF the chip draws about 60uA of power, which is way to much.

I made a small programm to test everything and found out, that using Interrupt pins will use a lot of power, but I thought, that this would only matter for systemON modes, as everything should get disabled in systemOFF mode... do I have to do anything else but

NRF_POWER->SYSTEMOFF = 1;

in order to get below 1uA?

my first thought was, that the chip may be in debug mode, but I uploaded the program, disconnected everything and then measured, and it was still that high.

my setup:

NRF52840-preview-DK + PowerProfilerKit.

Ps. when I have an empty int main() with only the systemOFF in it, I will get about 1uA power consumption, which is OK, but still strange as it should go lower?

[Jørgen Holmefjord]

Hi,

How did you configure the wakeup pins? You should make sure that the pins are not configured in a way that will draw current through pull-ups, etc.

Can you provide a minimal project that can be used to reproduce this issue on the DK?

Best regards,
Jørgen

[Jørgen Holmefjord]

In general, we do not provide much support on mbed, as it is being developed by 3rd party. I do not know how InterruptIn is implemented in mbed. Have you tested with other pins? P0.13 is connected to VDD through LED and pull-up by default on the nRF52840 (P)DK.

[jonas.woerner]

OK. I just verified it, its indeed the pullups and the LED, if I use P012, I get a poweroff current of 1.9uA.

however, I just noticed another problem, in my main program, I still see a constant current of about 38uA, but only if I used cryptographic functions prior.. Do I have to manually turn off the cryptocell hardware?

anyways, I will also ask this in the mbed forums, as its related to MBEDTLS.

one question for you though, Is 1.9uA an acceptable systemOFF current? I feel like it should drop even lower.

thanks for pointing me in the right direction!