NRF52832 Power & HFCLK

[SeanK]

I have a custom PCBA running my development firmware. When I turn everything off (meaning no peripherals are active - most chips are in sleep mode or de-powered; BLE disconnected & advert is off), i have a system quiescent current of 380uA (System powered at 3.5V); most of this current is supplying the NRF52. When i put the NRF52 to sleep, i see 80uA of current. I've tried to configure HFCLK to run off of the internal RC instead of the XTAL, yet I see no change to the above numbers. What could account for the 300uA difference in my power measurements? I see HFCLK might draw about 250uA - is there a way to confirm that it's running? If the HFCLK is on, is there a way to figure out which system is actively using it ? Are there other subsystems that might be using power that I should consider? Thanks.

[Kenneth]

Hi,

There is no easy answer here.

I would first recommend that you make very simple low power example, e.g. main() {while(1) __WFE();} just to verify that your measurement setup is working.

Once you start writing code and including peripherals they will claim internal resources (e.g. clocks, regulators, easydma etc) which will cause the base current to possible stay high while they are enabled. In general you should stop and disable peripherals when no longer used. So in this case you likely have one or more peripherals that are claiming resources, there is no easy way to identify which other than manually disable them until current is in the 1-2uA range when calling __WFE().

You should also check out the errata list for known issues that you should pay specific attention to:
https://infocenter.nordicsemi.com/topic/errata_nRF52832_Rev1/ERR/nRF52832/Rev1/latest/err_832_new.html?cp=3_1_1_1_1 

Floating input pins may also cause increased current consumption.

This blog post may also be useful:
https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/optimizing-power-on-nrf52-designs 

Best regards,
Kenneth