Current consumption on nRF52840 DK (PCA10056) at system on mode

[yanning]

Hi All, 

I want to verfiy the current consumption of nRF52840.  I'm using an nRF52840 DK and SDK 17.0.2 RTC example.  below are the verfiy steps:

1. Cut SB40 on PCA10056 board, use RIGOL DM3068 to measure the current through P22. 

2. Download firmware, then disconnect USB and power with battery, slide SW6 to nRF ONLY.  The current consumption is 4.5uA.

3. Comment  //leds_config(); //lfclk_config(); //rtc_config();, Still have 3.4uA current consumption. 

From nRF52840 specification 

ION_RAMOFF_RTC

System ON, no RAM retention, wake on RTC (running from LFRC clock)

1.50

µA

How can I get the1.5uA current consumption on nRF52840 DK? 

What's the firmware and hardware platform Nodic used?

Thanks.

[Stian Røed Hafskjold]

The 1.5 uA is without any RAM retention. All examples have all 256kB of RAM powered on by default. The current you are measuring corresponds to I_{ON_RAMON_RTC}

The numbers in the PS are typical numbers only, and there will be chip to chip variations.

To turn off RAM retention use NRF_POWER->RAM[n].POWER registers. You will have to allow some RAM to be retained on order for your application to run. And you will have to adjust the linker script accordingly.

[yanning]

Thanks a lot, Stian