Dealing the DC/DC in nRF51822

[Leo]

Hello,

I have questions about DC/DC setup in nRF51822.

1. Is there any automatic switching between DC/DC enable and disable along with battery voltage except DCDCEN register? That is, DC/DC is automatically disabled as battery voltage goes below 2.1V, and enabled as voltage goes to over 2.1V. If not, should S/W monitor battery voltage and set DCDCEN register?

2. How can I turn the DC/DC on in nRF51822 along with RF activity? Is RF_LDO_EN tied with DCDCEN in nRF51822, or S/W should set DCDCEN register whenever RF activity is on?

Thanks, Leo

[Stefan Birnir Sverrisson]

Hi

1. If you do not have a softdevice enabled, use the DCDCEN register to enable/disable the DCDC. If you have a softdevice enabled, use the sd_power_dcdc_mode_set function. Only use the DCDC with S110 softdevice version 8.0.0 and third revision hardware, not any older softdevice. If having older hardware, dont use with softdevice. See further recommendation here. You must manually disable the DCDC when supply voltage goes below 2.1V, and enable it when the supply voltage goes up again.

2. In the nRF51 Reference Manual it says: Enabling the DC/DC converter will not turn it on, but set it in a state where it automatically gets turned on when the radio is enabled and goes off again when the radio gets disabled. This is done to avoid wasting power running the DC/DC in between the radio events where current consumption is too low. The automatic operation is done by hardware so it will work with or without softdevice enabled.