nRF5340 DK USB & External Power

[k1minseok]

Hello.

I am using the nRF5340 DK.

According to the circuit diagram, it seems that when I apply power to VBUS_nRF, there should be no power on VDD_nRF of the MCU.

(Power only to VBUS_nRF, Switch9 is located on VSRC_NRF)

And it looks like the nRF5340 only powers up the VBUS and nothing else but the application core.

I think it doesn't work when I apply power to VBUS only, but it needs to apply power to VDD too.

However, I checked 3V voltage on the VDD pin on the DK board.

Am I missing something?

[k1minseok]

In the circuit above, we see that the VDD pin(pin number 1 of P1) of the DK board is connected to VIO.

However, as shown in the circuit above, VIO is fed through VDD and VDD is fed through VSRC_NRF only when SW10 is turned ON.

When power is applied to VBUS_nRF only,
@ SW10 == OFF) VDD pin = 3V
@ SW10 == ON) VDD pin = 2V
is measured.

When SW10 == OFF, shouldn't 0V be measured on VDD pin?

[JONATHAN LL]

What version of the DK do you have? what does it say on the sticker?

Regards,
Jonathan

[k1minseok]

Hello Jonathan

My DK version is 2.0.

The versions of DK and schematic match.

[Sigurd]

Hi!

Jonathan is out of office today, so I'm answering instead.

When the nRF5340 is in High voltage mode, The VREGH regulator supplies the VDD pin.

https://docs.nordicsemi.com/bundle/ps_nrf5340/page/chapters/supply/doc/power_supply.html#ariaid-title3

 In high voltage mode, VDD voltage equals the level specified in the VREGHVOUT register.

https://docs.nordicsemi.com/bundle/ps_nrf5340/page/regulators.html#ariaid-title5