Measuring 300nA, SystemOFF nRF51822, is it correct?

[Brian]

A good problem to have... we're only seeing 300nA current draw with a 3V lithium primary while in SystemOFF on the nRF51822, using LDO.

Is that correct? We've measured with both a Keithley 2450 and Keysight N6705B, and they're both giving us consistent results.

According to the data sheet though... I thought we should be at 600nA? Wow. How low can the nRF52 go? Will that chip also have the "1Byte of retained RAM" (GPREGRET register)? A really nice feature.

Sanity check here would be awesome. Thanks! Brian

[Håkon Alseth]

Hi Brian,

One of my devices also have a current consumption of approx. 300-400 nA in SYSTEMOFF (measured with fluke/keysight etc) with no RAM retention, while most of my devices are closer to the specified 600 nA.

What you should note is that the current consumptions specified in the datasheet are at nominal conditions (3V, 20 degrees) and may vary if parameters changed. In addition, most multimeters have a higher error tolerance when going sub micro-ampere, so the number you get can be misleading.

The nRF52832 is rated a bit higher than nRF51x22 in system off: infocenter.nordicsemi.com/.../parameters.id_current_ulp.html

A nice feature about the nRF52832 is that it actually has 2 GPREGRET retained registers: infocenter.nordicsemi.com/.../power.html

Cheers, Håkon