0.23uA consumption when deep sleep

[Jose Xavier]

Hi,

I enable nrf51822 deep sleep mode with 

NRF_POWER->SYSTEMOFF = 1;

and got 0.23uA current consumption instead of 0.6uA expected current consumption. What is happening?

This is the board I'm using https://pt.aliexpress.com/item/Low-Power-NRF51822-Wireless-Module-2-4G-Wireless-SOC-Single-Chip-BLE4-0-Bluetooth-Module/32334236969.html?spm=a2g0s.9042311.0.0.15a7b90auPCrsp and I did test with two different multi-meters. One of them (unit ut61e) I used some years ago to measure a nrf51822 deep sleep current with sucess.

[rogerarchibald]

What type of test equipment are you using to measure current?  Sub-mA I would be skeptical of the accuracy of most meters. 

It may be useful to know more about the board as well, but since we’re talking about drawing less current than expected I would assume that it’s a measurement issue. 

[Jose Xavier]

I update my question

[rogerarchibald]

The DC current measurement specs for that meter include the following line: 

DC Current Measurement:
220µA / 2200µA +/- (0.5%+10)

There's a +/- of >10uA and you're talking about a discrepancy of a few hundred nA. I think that it is nothing to be too concerned about.

[Jose Xavier]

0.5% of 220uA is 1.1uA +10 digits gives 0.11uA of accuracy.

It is strange that the value is the same on two completely diferdiff multi-meters.