Hi,
I'm using an nRF9160DK v1.0.1 (2021.26) for developing an application on the nRF9160 with ncs v2.5.0 and I'm currently looking to optimize current consumption. I realize that the nRF9160DK is not optimized for low power, but I want to make sure I understand the intricacies of the ncs configurations to get the lowest possible current consumption.
I'm measuring current consumption with a PPK2 using the dedicated current measurement header (P22) for the nRF9160 on the DK. I had a look at the schematic and I didn't see anything connected to VDD_nRF91 that would lead to significant parasitic consumption. As a reference, I was following the webinar How to measure current consumption on the nRF9160 SIP and I noticed on the slide presented at around 14:10 that the current consumption should be around 1.4µA with everything off and 1.8µA with MCU idle and everything else off.
To try and get to these numbers, I started from the system_off sample. I would expect that running the sample as is should get me to the 1.4µA number, and commenting out the sys_poweroff() would get met to the 1.8µA number, as this would prevent the MCU from powering down. I'm not clear on whether the modem is off at startup (I would assume it is), but just to make sure I also added lte_lc_power_off() to turn off the modem (enabling CONFIG_NRF_MODEM_LIB and CONFIG_LTE_LINK_CONTROL to be able to include the modem/lte_lc header).
.When I run the system_off sample on the nrf9160dk_nrf9160_ns build target, I get however around 2.5mA with or without lte_lc_power_off(). I thought TF-M could be the culprit, so I also tried to build the nrf9160dk_nrf9160 build target, but this didn't result in any changes to the current consumption. Since the nrf9160dk_nrf9160_ns is not supported by default by the system_off sample, I am probably missing some configurations to get to the listed consumption of 1.4µA. Could you provide me with some points to how I can achieve the lowest current consumption on the nRF9160?
I'm planning to then work my way up to my final application, enabling peripherals and functionality piece by piece to get a good understand of the contribution of each piece to the overall current consumption.
