how to disable dcdc of nRF52840 in NCS v2.9.1?

RE: how to disable dcdc of nRF52840 in NCS v2.9.1?

Håkon Alseth — Fri, 13 Mar 2026 15:54:14 GMT

Hi,

I assume your design does not have an external LFCLK src?

Try setting this to enable internal 32k RC oscillator:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

Kind regards,

Håkon

RE: how to disable dcdc of nRF52840 in NCS v2.9.1?

always18 — Fri, 13 Mar 2026 15:04:32 GMT

hi, I added the following to the board overlay file:

&reg1 {
regulator-initial-mode = <NRF5X_REG_MODE_LDO>;
};

when i power on the board,it don't work.

and when i power on it and connected the jlink,it works well.

what's wrong?

RE: how to disable dcdc of nRF52840 in NCS v2.9.1?

Einar Thorsrud — Fri, 13 Mar 2026 13:58:54 GMT

Hi,

To disable the DCDC, modify the board file for your custom board to specify using LDO instead like this (you can also put this in an overlay file):

&reg1 {
    regulator-initial-mode = <NRF5X_REG_MODE_LDO>;
};

RE: how to disable dcdc of nRF52840 in NCS v2.9.1?

Håkon Alseth — Fri, 13 Mar 2026 13:58:43 GMT

Hi,

For NCS v2.9.0 and later (which applies to v2.9.1), the DCDC regulator configuration has moved to the device tree rather than Kconfig. You need to add the following to your board overlay file:

&reg1 {
    regulator-initial-mode = <NRF5X_REG_MODE_LDO>;
};

Ref: RE: What exactly is required to run USB on an nRF52840 without an external crystal?

Kind regards,

Håkon