High current consumption (~670 µA) in eDRX and PSM on nRF9151 DK

RE: High current consumption (~670 µA) in eDRX and PSM on nRF9151 DK

Håkon Alseth — Tue, 14 Apr 2026 17:46:08 GMT

Hi Hassan,

I would recommend that you look into using serial lte modem if you require AT commands:

https://github.com/nrfconnect/ncs-serial-modem

You can set it up in sleep mode: https://docs.nordicsemi.com/bundle/addon-serial_modem-latest/page/app/at_generic.html#power_saving_xsleep

[quote user="Hassan0"]If I disable UART using CONFIG_SERIAL=n, I assume I will no longer have access to AT commands via UART. In that case, does it mean I need to rely only on a C firmware implementation (using the nRF Connect SDK / LTE link controller APIs) to configure PSM/eDRX and operate the modem?[/quote]

Yes, this is correct. PSM is automatically requested. You can look at samples like ncs/nrf/samples/net/udp for a smaller example that provides minimal communication.

[quote user="Hassan0"]Is there any recommended or supported way to disable UART at the hardware level on the nRF9151 DK (for example using solder bridges or board configuration), in order to reduce power consumption while still keeping some form of debugging or alternative interface if needed?[/quote]

The issue is keeping the uart active inside the nRF, which causes the peripheral clock tree to be on while in sleep/idle mode, not the external physical connection itself.

Kind regards,

Håkon

RE: High current consumption (~670 µA) in eDRX and PSM on nRF9151 DK

Hassan0 — Mon, 13 Apr 2026 13:50:20 GMT

Hi Håkon,

Thank you very much for your clear answer.

I have a couple of follow-up questions to better understand the recommended approach:

If I disable UART using CONFIG_SERIAL=n, I assume I will no longer have access to AT commands via UART. In that case, does it mean I need to rely only on a C firmware implementation (using the nRF Connect SDK / LTE link controller APIs) to configure PSM/eDRX and operate the modem?
Is there any recommended or supported way to disable UART at the hardware level on the nRF9151 DK (for example using solder bridges or board configuration), in order to reduce power consumption while still keeping some form of debugging or alternative interface if needed?

Thank you again for your support.

Kind regards,
Hassan

RE: High current consumption (~670 µA) in eDRX and PSM on nRF9151 DK

Håkon Alseth — Mon, 13 Apr 2026 11:43:41 GMT

Hi,

Your setup for measuring current is correct.

[quote user=""]2. Could an active UART or another peripheral explain this ~670 µA consumption?[/quote]

Yes, this is usually the reason why you are seeing a higher floor current than 3 uA.

[quote user=""]3. Are there specific steps to ensure the system reaches true ultra-low power (µA range) in eDRX/PSM on the nRF9151 DK?[/quote]

Have you disabled UART for instance? Check if "CONFIG_SERIAL=n" is set on your side.

Kind regards,

Håkon