nRF52840 connecting to power supply

[PartUser]

Hi,

 

I do use a power supply which generates +3.3V and +5.0V .

Please, could you explain me what will be the energy efficient  way to connect them to nRF52840?

VDD_HV = +3.3V

VDD_nRF = will be generated by nRF82840

Is this way okay?

 

Thanks in advance

[Alpha]

Take a look at this: http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/development/nrf52840_pdk/hw_power_supply.html

VDD_nRF will not be generated by the nRF52840. The VDD_nRF are the powerlines connecting to the nRF.

You can connect your 3.3V to the external supply pins (P21) on the nRF52840 preview development kit. No need to connect it to the VDD_HV.

[PartUser]

Sorry I do not understand your suggestion.

Looking at the attached schematic:

1) connecting +3.3V (from main supply) to VDD_nRF?

2) no USB used => connecting VBUS to GND?

Thanks for your help!

[ovrebekk]

Hi

Please refer to circuit configuration no. 6 in the nRF52840 OPS. 

This shows how to connect the various pins when not using the USB interface, and not using VDDH. As Alpha said there is no need to use VDDH (VDD_HV) when you have access to a 3.3V supply, unless you want to use a lower VDD and GPIO voltage. 

For optimal efficiency you might want to use the DCDC1 regulator. This one is not used in circuit configuration no. 6, but you can copy the DCDC1 related circuitry from circuit configuration no. 5 (namely L2, L3, C15 and C16). 

Best regards
Torbjørn

[PartUser]

thanks a lot for the fast reply

Please, do not close this topic - I would like to come back with an additional question

Thanks again

[ovrebekk]

No problem, I will set the case to idle in the mean time.