nRF9160 LTE-M current profile

[Martinizhr01]

Hello everyone, 

I need some help in understanding and optimizing current consumption profile of nRF9160 in LTE-M cellular connection mode. 

nRF9160 is implemented in custom board and is powered by Lithium Thionyl Chloride battery (3.6 V). All other peripherals on board have been powered off or set to low power state. 

Device also has a debug output thru uart. I measured that this uses around 2mA.

My main question is why is there so big difference between what I get from the Online Power Profiler for LTE - opp - Online Power Profiler - Nordic DevZone and from my measurements? 

On the online tool, current consumption shows that it should be much less and communication should be faster. Does anyone have any ideas what is happening there? I am very close to the cell tower and signal is strong.

Also, I am not sure why is there 4 current spikes lasting around 2 seconds with the average current of 43mA, I am not sure what they are. Debug output during those spikes shows this: 

Can someone help me understand what is happening there? 

Thank you in advance, 
Martin

[Achim Kraus]

If you search this forum, you will find a lot of answers.

1. if you don't use PSM, the device will not go to sleep mode. Once you enable it (and the MNO/provider supports it), your current should go down to 400µA.

2. If the UART is not suspended, the RX sampling drains that 400µA. Suspend the UART or disable it in the device tree and you will be down to 4µA.