Supply nRF52840 with 5V battery supply

[uwvid]

Hi. 

I am looking to implement a nRF52840 chip in my 5v battery operated door lock. 

Sorry if this is asked before or should be clear from documentation, but I am not completely sure about the operating procedure. 

Door locks and unlocks by pulling each pin high for some ms. Lets say I use the nRF52840’s p13 and p20. Preferably the output should be 5V, but lower should work also. 

If I understand correct, the most power efficient way to power the chip with 5V is by using the DC/DC converter and : 

• DCDCEN0 and DCDCEN needs to be set
• 5V supply connected to VDDH
• DCCH connected VDD, via a 10uH inductor as a LC filter (https://www.ebay.com/itm/CD32-SMD-Power-Inductors-Different-values-available-10-pack-UK-SELLER/264560330339?hash=item3d99064663:g:T5IAAOSwF~1d7Puj) 

• P13 and P20 high reference voltage will need to be set in REGOUT0 (5v)
• I will not need to connect power supply to VDD?

[ketiljo]

The procedure is correct, except that all GPIOs will be referred to VDD or REGOUT0. You can set this to max 3.6 V.

Refer to this schematic: https://infocenter.nordicsemi.com/topic/ps_nrf52840/ref_circuitry.html#unique_1073517861