nrf52840 + Zephyr + Blinky: Sleep Power consumption

[tomatosoup]

Hello

I have the blinky example (ncs/zephyr/samples/basic/blinky) running on a minimal nRF52840 holyiot module. I changed the sleep time to 5000ms.

When measuring the 3.3V current, I see a current of ~150uA while the LED is off. Is this normal? Shouldn't this get way lower?

My prj.conf:

CONFIG_GPIO=y

CONFIG_SERIAL=n
CONFIG_LOG=n
CONFIG_CONSOLE=n
CONFIG_UART_CONSOLE=n
CONFIG_RTT_CONSOLE=n
CONFIG_USE_SEGGER_RTT=n
CONFIG_PRINTK=n

CONFIG_PM_DEVICE=y

[tomatosoup]

I'm trying to check the current in "SLEEP" state. The device will be Battery operated, thus this value is very important. But currently it needs >100uA, which is too much.

The device should later wait for button presses. Thus, my decision was to start with the blinky example as a starting point to do these checks.

I did check the `Optimizing Power on nRF52 Designs`, but this Article seems to be written for the
nRF5 SDK, which Nordic doesn't recommend for new projects.

According to this Article, I should reach a current in the range 1-2uA. Is it possible that with Nordic Connect SDK, this isn't possible anymore?

[tomatosoup]

I have found the issue. Loading my hex file on a nRF52840 DK and meassuring the sleep current there resulted in ~4uA.

Then I have checked my board again and noticed that the LDO was still there and backfeed by my 3.3V external supply! After removing the LDO my Board is now also ~4uA.