Current consumption of the modem inside nRF9160

[WassimZ98]

Hello. I have a DK nRF9160 0.8.2 version. I am sending AT command through UART with an external MCU (STM). I am interested on evaluating power consumption during an UDP packet transmission and on PSM mode. My multimeter shows a consumption of about 485uA in PSM, it is far higher than the 4uA provided on the datasheet. With a research i understoodthat UART consumes that power, but i need it for serial communication with external mcu. So, is there a way to only measure current consumed by the modem and not by the entire SiP nRF9160?

Or, is there a way to disable via software the UART, for example by sending an AT command? 

Thanks in advice

[WassimZ98]

I have tested the Serial LTE modem firmware, but i see a strange behaviour. 

I am supplying power from the USB port J4. The switch nRF ONLY is on. I am measuring current with a multimeter. When the VDD_IO switch is set to 1.8V, the current is about 5uA (modem is PSM and I isued the AT#XSLEEP=0 command). But when the VDD_IO switch is on 3V the current is insignificant, about 0.2uA. Is it normal?

[Martin Lesund]

Hi Wassim,
Could you please redo the test while the nRF ONLY switch is to the left and VDD_IO is 3V ?

Since there is a bug on that DK version you should have these configurations.

[WassimZ98]

Almost same thing, but this time the current oscillates between 0.6uA to 1.3uA.

[Martin Lesund]

There is something incorrect with your test setup when measuring the SLM sample.
Please make sure you have prepared your DK nRF9160 0.8.2 version correctly for measurements and also use another measuring equipment to have something to compare with.

[WassimZ98]

OK I will try. I have another question regarding RSSI. Can i know directly the RSSI value? The AT commad CESQ only gives me RSRP and RSRQ. 

[Martin Lesund]

RSSI is not detectable, RAT not supported. Use +CESQ and %CESQ for E-UTRA signal quality.