[209] CLOCK: LFRC ULP mode calibration not functional

This anomaly applies to IC Rev. Rev 2, build codes QIAA-Dx0, CKAA-Dx0.

It was inherited from the previous IC revision Engineering D nRF52840.

Symptoms

LFRC stops.

Conditions

Sometimes when using LFRC ULP mode and performing calibration.

Consequences

LFRC ULP mode cannot be calibrated.

Workaround

Use LFRC ULP mode without calibrating, or use LFRC normal mode if calibration is required.