[197] POWER: DCDC of REG0 not functional

This anomaly applies to IC Rev. Rev 1, build codes QIAA-Cx0, CKAA-Cx0.

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

Symptoms

VDD voltage drop below specification when entering low power modes. Low voltage may trigger reset of device.

Conditions

Using DCDC on REG0, high voltage mode. DCDC on REG1 is not affected.

Consequences

Cannot use DCDC and switch to ultra-low power mode (autonomous). Cannot support external circuitry supply.

Workaround

One of the following options:

  1. Do not enable DCDC.

    Consequences: Loss of efficiency with high dropout between VDDH and VDD. Supports external circuitry supply.

  2. Prevent REG0 stage to go to ULP mode. At startup and after reset, write 0x00000001 to register 0x40000638.

    Consequences: High current consumption in System ON IDLE (~300 µA). Cannot support external circuitry supply.