System_off example has increased power consumption when using k_sleep iso system_off

[Ypenburg]

I run the system_off example without the system actually going off, by removing all the calls to start the system_off worker. Instead of going to off, I let the system enter sleep mode (k_sleep()).

I enabled wake up on nfc.

After a reset, the system enters sleep (4-5uA sleep current). After waking the system by nfc, the sleep current sometimes becomes 200uA, sometimes stays at 4uA. See picture below.

It seems to be related to the state of the nfc peripheral as this is the only peripheral used.

Any idea how to prevent the system going to sleep with a 200uA sleep current?

[Simonr]

Thanks Renger

I'm now able to reproduce it and it does indeed seem like a bug with the nRF54L15 part of this application since I can't reproduce the same behavior with an nRF52 series DK unless there's something obvious I'm missing. I have reported it internally now and hopefully we'll find the root cause soon. For now, is there a specific reason you need k_sleep instead of system_off() as the system off function seems to work without a hitch.

Best regards,

Simon

[pyfh]

Hi Simon,

Thanks for looking into this!

I'm working on a similar application where power consumption is also a key concern. Like Renger, we primarily rely on system_off() most of the time. However, during BLE connections, we also need NFC to be able to trigger certain operations at any time.

While the BLE connection alone has a normal current consumption of around 30 µA, enabling NFC introduces some irregular behavior — sometimes the current remains at 30 µA after NFC is triggered, but other times it rises to around 220 µA. This inconsistency makes it difficult to pinpoint the cause.

Could this behavior be related to the same issue, or is there something we might be missing in the way NFC is handled in combination with k_sleep() on the nRF54L15?

Thanks in advance for any guidance.

Best regards,
Phelan

[Ypenburg]

Hi all,

I don't know if I made it clear in the previous posts.

As Phelan, I only see the problem when using NFC. It either enters sleep just fine, or I see the higher sleep current of around 200uA.

Best regards,

Renger

[pyfh]

Hi Renger,

Yes, I actually understood your point — thanks again for the clarification.

I can now confirm that I'm seeing the exact same behavior on my side as well. When using only NFC, the device either enters sleep with low current (around 30 µA), or sometimes it stays at a higher sleep current of around 200 µA, just like you mentioned.

Best regards,
Phelan