NRF53 High power consumption on in power_off state - Zephyr

[Christian Holland]

Hi

I've run up the system_off sample (samples/boards/nrf/system_off) and I can see chip fall into deep sleep, but deep sleep still seems to be sitting at 152 microamps, which seems to be quite high?

Below are the usage screenshots, first one showing dropping from active to power_off state, and the second showing the consumption over 30 seconds in power_off state

I have tried turning off UART, as this could be a possible cause of consumption in power_off state. I know that it is not waking up out of power_off state because I can see that in the consumption, but it is still using power.

Why is it still using this much power?

[Stian Røed Hafskjold]

Hi, are you measuring on a DK? Which version is it? I know that at least 0.7.0 has some current consumption problems.

[Christian Holland]

Hi yes I am measuring the current on the nrf53 DK but I have also measured it on a few custom boards and it is high consumption still. Not sure which version you're referring to?

[Stian Røed Hafskjold]

Can you try to flash this hex? systemoff.hex

It puts the regulators to system off mode. If you get more than about 1uA you have a leakage somewhere.

The version I was referring to is the DK version which is written on the sticker on the DK.

[Christian Holland]

I have flashed the code on and it seems to be using 6 mA which is a lot!

[Stian Røed Hafskjold]

So which DK version do you have? I need to know which hardware you are measuring on before I can help you. If it's a DK, it need the DK version. If it's a custom board I need the schematics. The chip does not consume 6mA or even 150uA in system off, so we need to figure out where the leakage goes. In your original code do you configure any GPIOs?

Can you also describe your test setup? If you measure current going in to the external supply header it includes the current going to the debugger chip and everything else on the DK.

[Christian Holland]

Appreciate your help - I'm actually running it on NRF52 DK and only have access to NRF52 chips now but I had the same result on a borrowed NRF53 chip hence this ticket.
It is the NRF52 DK v1.2.4 (2019.8)

- I have also tried this on the NRF52832 Raytac Development Board and had the same result. Schematic is here: https://www.raytac.com/product/ins.php?index_id=82
- I have also been testing this on a barebones board with an nrf52832 chip only (no external crystal)
- I am also going to soon try this with a custom board with an external crystal so I will be able to provide a schematic for that when I get it. This will be NRF52 as well.

I'm measuring the current going through the external supply header as you mentioned, but I unplug the USB, but I see what you mean regarding consumption with other things on the DK.
The original code did not configure GPIO's - just simply tried to put the chip in system off state

[ovrebekk]

Hi Christian

I have agreed to help Stian out with this case as he will be out all next week. 

Can you confirm what results you get when running the system_off example on the nRF52DK?

I just tested this myself, and see about 45uA in system off mode. This is still too high, but seems quite different from the numbers you are reporting. 

Can you confirm what you get on the nRF52DK, and I will do some checking with the NCS/Zephyr team to see if there is some way to optimize the example. 

Best regards
Torbjørn

[ovrebekk]

Hi again

One tip is to disable the serial interface by setting CONFIG_SERIAL=n in prj.conf and rebuilding the project. 

Then you should expect to see lower sleep currents. 

Please give this a go and see what results you get. 

Best regards
Torbjørn

[Christian Holland]

Hi, thanks for your response much appreciated, I have flashed my DK but before I go into in depth consumption testing could you tell me the best way to measure consumption on the DK? Because currently I have a 3v supply going through a DC energy analyzer, which is then hooked up to the external supply pins on the board. This alone does not seem to power the DK though, and it only turns on when I plug in the micro USB?

[Christian Holland]

Not sure my sample is working correctly because it's sitting on 49ua with a supply current of ~3v and pressing the buttons doesn't seem to do anything. Also no sign of a drop off when it goes into system_off mode. I'll try reflashing it...

[Christian Holland]

When i have only my 3v external supply plugged into the external supply pins, the consumption seems to increase permanently in a linear fashion and the supply voltage seems to plummet in the same: