Supply only my nrf52840 with minimum power consumption

[ElectroMax]

Hello!

I'm a beginner with Nordic products and I'm taking over the nRF52840 Preview Development Kit.

I want to send advertisings at regular intervals (every second). Between advertisings, I want to go in sleep mode. To do this, I used the following example program, with some minor changes:

<InstallFolder>\examples\ble_peripheral\ble_app_beacon. I used nRF5 SDK v14.1.0 and S132 softdevice.

I want to put an external power supply that consumes a minimum of energy, to power directly my nRF52840. My software must obviously continue to work.

I tried to put the external power supply (3V) on the P21 connector (Switch SW6 is on “nRF only” / Switch SW9 is on position VDD). But, I consume about 2.6mA, which doesn't correspond at all to sleep mode... If I measure on connector P22 with a good multimeter (with SB40 cutted), the current consumption is about 2uA in sleep mode, as desired.

Where should I put the external power supply for minimum power consumption only (some uA in sleep mode)? Do I have to modifie other switches or solder bridges?

Thank you in advance for your answers!

[ElectroMax]

Can't anyone help me?

[Alpha]

I am currently working the same problem, what I found helpful is the following:

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/development/nrf52840_pdk/direct_supply.html

It says: "Since it is only the nRF52840 SoC that is supplied from this source, it is recommended to supply the VDD domain from a different source (coin cell battery or USB) to prevent the pins of the SoC to be connected to unpowered devices. To prevent leakage due to voltage differences, the board should be set in the nRF only mode."

For me this is the solution and resulted in a current drain of a few uA.

If you do not want to deal with all of this you need to create your own PCB with only a nRF and your power supply.

[ElectroMax]

Thank you for your answer. I think you're right. So my problem is solved.