High Current Consumption on nRF9151-DK

[Oleg-AgamControl]

According to the nRF9151_PS_v1.1 specification, when using PSM, the current consumption should be below 5 µA ("LTE power saving mode (PSM) floor current – 2.7 µA").

However, when I use the nRF9151-DK (powered via Power Profiler through VDD_NRF), I observe a current consumption around 300 µA to 400 µA, even with the modem completely turned off (AT+CFUN=0).

I am using the Zephyr OS, and in the cases I checked, the application does not perform any activity in the main loop after the modem is turned off.

Could you please clarify:

1. Why am I seeing such high current consumption?

2. How can I achieve the expected low-power consumption?

3. What is the minimal current consumption I can realistically measure on an nRF9151-DK running an idle program with the modem turned off?
   
   

Additional question:

I understand that it is technically possible to put the application and the processor into some SLEEP mode. Is it possible to combine this sleep mode with the modem operating in Power Saving Mode (PSM)?
In other words, what is the recommended way to achieve minimal power consumption while keeping the modem run in PSM?

Thank you for your assistance

[Achim Kraus]

Oleg-AgamControl said:

around 300 µA to 400 µA

First guess (you will find a lot of tickets about that current value), this is an active UART. Disable it or use the power manager to suspend it. And then see, what you get. 

[Simonr]

Hi Oleg

I just want to say that I agree with Achim here, and this does indeed sound like an active UART. If you'd like, you can upload the zephyr.dts from your build folder so we can see what is enabled or not?

Best regards,

Simon

[Oleg-AgamControl]

Thank you for your reply. I will try to run the tests soon and let you know the results.
In any case, could you please tell me what current consumption we should expect after fully UART deactivating?