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

[Priyanka]

Hi,

Which SDK version are you working on?

Best Regards,

Priyanka

[tomatosoup]

Hello

I'm using v3.3.99-ncs1-rc1

[Priyanka]

Hi,

I am looking into this. Meanwhile, please take a look at optimizing power on nRF52 devices and see whether it helps.

-Priyanka

[Priyanka]

Did you follow the product guide in the Holyiot page ? Have you connected all the GND pins to ground and VDD to VDD?

-Priyanka

[tomatosoup]

Yes, I have posted my schematic above.

[Priyanka]

Priyanka said:

please take a look at optimizing power on nRF52 devices and see whether it helps.

Please take a look at this. 

Also, have you tried any other samples? Maybe the hello_world sample, or just an empty while() sample which can help see the current consumption.

Could you also specify why you are concerned regarding the current draw for the blinky, i.e. what is it that you wish to achieve?

-Priyanka

[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.