I am designing a wireless sensor pcb with the nRF52840. I am essentially following the Circuit configuration no. 4 schematic for QIAA aQFN73 from the datasheet to a tee (schematic from datasheet below in pdf form). I intend to power this MCU from a 3.3V from an external LDO, but I would also like to utilize nRF52840's built in capability to supply 1.8V to external circuitry. I had some questions regarding the power supplies:
1. What is V_ext as shown in the schematic? Based on the label wording, I'm guessing it's the "1.8 V to 3.3 V regulated supply for external components". But then it doesn't make intuitive sense to me that Vdd_nRF, which I understand is the Vdd, would be routed to the same pin. But if this is where the regulated supply would output, I would just via this connection to my power layer and it would supply 1.8V? (given I have the MCU programmed correctly). If not where from the nRF52840 would the output supply be coming from?
2. I have an external LDO/buck converter that provides a 3.3V. Can I have the VDDH pin to be no connect status in my schematic? and route all the VDD_nRF connections referenced in the suggested circuitry to my 3.3V power layer?
Thanks!
