RE: Recover nRF5340 / MDBT53 after wrong DCDC config on LDO-only board

Kazi Afroza Sultana — Wed, 15 Jul 2026 06:49:50 GMT

Hello,

Can wrong DCDC/regulator configuration prevent SWD access on nRF5340?

Wrong DCDC configuration causes device to behave abnormal for example sudden reset or unresponsive.

If the device resets or hangs or crashes at startup due to regulator misconfiguration, there is a high chance not to be reachable over SWD. As after each reset APPROTECT requires firmware re-enable debugger access before the next one. UICR includes regulator configuration registers like UICR.VREGHVOUT.

2. If SWD can be reached, will nrfjprog --recover / ERASEALL clear the bad UICR/regulator setting?

Yes, nrfjprog --recover or eraseall command does eraseall operation via CTRL-AP which erases flash, SRAM and UICR (which includes regulator configuration registers like UICR.VREGHVOUT).

3. Is there a recommended connect-under-reset or recovery sequence for this failure mode?

You can read this blog (+) Allowing debugger access to nRF5340 - Blogs - Nordic Blog - Nordic DevZone

4. I need to talk to team to be sure of this query.

Thanks.

BR
Kazi