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?

[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:

[Christian Holland]

Hi, managed to get the system_off working and the consumption readings are the same as i measured before. I have turned CONFIG_SERIAL=n in the prj.conf.
Here is the consumption graph, showing a reading of ~200ua in system_on, and then falling to a lower reading (but still spiking back to ~200ua) in system_off mode

And then here is that system_off mode more closely:

What version of the NRF52 DK do you have? Is it possible that 1.2.4 (2019.8) has this issue?

[ovrebekk]

Hi Christian

The most common way to measure current is to cut solder bridge SB9, and connect an ammeter to the P22 - nRF current measurement connector. Then you can directly measure the current going into the chip (excluding external current consumption from LED's and other DK electronics). 

When doing this it is important to short P22 whenever you don't use the ammeter, otherwise current to the chip will be cut (or reconnect SB9). 

Alternatively it should be possible to supply the chip through the P21 - External supply connector, and measure the current going to the board if you have a tool that can supply the chip while measuring the current. 

The board I have been testing on is v1.2.1 (2017.22), so a slightly older one, but I doubt the board version is the issue. To my knowledge the difference between these two versions are minimal. 

Best regards
Torbjørn

[Christian Holland]

Thanks for your help! I do have a tool that can supply the chip while measuring the current so i'll go with that option, I'm a little confused with your instructions though - 
1) I thought P21 was the reset pin for the nRF52? Confused as to how to use that for supplying voltage here
2) I have been supplying voltage through the external supply pins - is that not the same as the external supply connector? Because i thought the complication there was that it was also measuring the other components on the board and not only the chip consumption?

Sorry for not understanding

[ovrebekk]

Hi Christian

1) All the headers and connectors on the board have a unique Pxx name. If you look closely at the PCB you should see this printed in white next to the connector. 

The GPIO names should start with the port number followed by the pin number, so P0.21, not just P21. 

2) I assume it is the same, yes. If you can see "P21" printed next to them then we are on the same page

Best regards
Torbjørn