RTC wake up not happening in system-off mode

[vineeshvs]

Hi,

We are using system-off mode to save power in our device which uses nrf51822 chip. Our application requires regular wake-ups using RTC interrupts.

But the wake up is not happening since RTC is also off during system-off mode.

1. Any suggestions to implement lowest power mode with only RTC running in the background?
2. Can we turn off everything except RTC in system-on sleep mode? How much minimum current consumption can be achieved using system-on sleep mode?

[endnode]

There is no workaround for this, RTC wont's run on nRF51 or 52 in SYSTEM OFF mode. You can indeed turn off pretty much everything (including SD) except one RTC and keep it in SYSTEM ON SLEEP. If you are not satisfied with that you can design custom board with external low-power RTC which will get configured before you send nRF5x to SYSTEM OFF and wake it up by PIN interrupt.