Use PPK2 testing nrf9160 PSM and eDRX power consumption

[Devin Li]

Dear Support team,

I used PPK2 to test the PSM mode current of nRF9160 is about 7.09uA (as shown in the figure below),but the eDRX mode current has not been tested successfully.

I am using Modem FW  v1.2.3, UDP sample code of NCS v1.4.1 , nRF9160 DK v0.8.5, config to NB-IOT network ,  part of prj.conf is as follows:

```
# LTE parameters
## Network Mode / LTE category
#CONFIG_LTE_NETWORK_MODE_LTE_M=n
CONFIG_LTE_NETWORK_MODE_NBIOT=y
CONFIG_UDP_SERVER_ADDRESS_STATIC="169.254.84.149"
CONFIG_UDP_SERVER_PORT=123

## PSM
CONFIG_UDP_PSM_ENABLE=y
CONFIG_LTE_PSM_REQ_RPTAU="00100001"
CONFIG_LTE_PSM_REQ_RAT="00000000"

## eDRX
CONFIG_UDP_EDRX_ENABLE=y
CONFIG_LTE_EDRX_REQ_VALUE="0000" #"1001"

## RAI
CONFIG_UDP_RAI_ENABLE=y
CONFIG_LTE_RAI_REQ_VALUE="4"

#LOGls
CONFIG_LOG=n
CONFIG_USE_SEGGER_RTT=n
CONFIG_LOG_BACKEND_RTT=n
CONFIG_AT_HOST_LIBRARY=n
CONFIG_RTT_CONSOLE=n
CONFIG_UART_CONSOLE=n
CONFIG_LOG_PRINTK=n

CONFIG_LOG_DEFAULT_LEVEL=3

```

I saw on a Nordic PPT that the current in PSM mode can reach 4uA, which is a bit different from the 7uA I measured. Is the 7uA I measured is normal? It is 3uA different from the data on the Nordic PPT. Is this caused by the accuracy of PPK2?

Best regards,
Devin

[Stian Røed Hafskjold]

Hi, In the plot you posted, the 7 uA includes the whole window, which includes the radio part as well. Can you try to select only the idle part by holding down shift (as instructed in lower right part of the plot itself)?

On earlier DK versions (including 0.8.5 as you have) we had a problem with leakage currents through the reset pin if the IO voltage voltage was set to 1.8V. Try to set the VDD IO switch on the DK to 3V (placed next to the power switch), to remove the leakage current. Are you able to reach 4 uA now? The PSM floor current varies a little bit from chip to chip, but 7 uA is too much and indicates a measurement error.

[Devin Li]

Hi,  I set the VDD IO switch on the DK to 3V, then the current value measured with ppk2 as follow:

[Stian Røed Hafskjold]

Can you try to connect the PPK2 as shown in the picture below? Use source meter mode and set the output voltage to 5V

[Devin Li]

Hi,  according to the "source meter" mode method, the measured current should be normal.

[Stian Røed Hafskjold]

Ok, that looks better. The reason why the ampere meter mode is showing a higher current is because of switching noise from the DK onboard regulators, so it's hard to measure the lowest idle currents in this mode. Using the PPK in source meter mode powers the nRF91 directly avoiding using the noisy regulators as source.