topic Re: mcxn947 external dcdc powered in MCX Microcontrollers

mcxn947 external dcdc powered

TomC818 — Mon, 16 Jun 2025 05:45:39 GMT

Hi all,

Although the mcu has integrated ldo and dcdc converter to provide the power for the core. Is there any guide on how to bypass both integrated converter and use solely external converted to provide the power? I know that the datasheet and HDG have mentioned either the DCDC or LDO can be bypassed, but the HDG has no mentioning of using entirely using external power to supply the mcu. On top of this, are there power sequence for this particular mcu?

Re: mcxn947 external dcdc powered

TomC818 — Mon, 16 Jun 2025 07:06:42 GMT

I also want to ask how to disable the internal regulator in the code? The design guide mentioned if the internal regulator is bypassed, the regulator should be disabled.

Re: mcxn947 external dcdc powered

Harry_Zhang — Sat, 21 Jun 2025 13:14:24 GMT

Hi @TomC818

You can supply VDDCORE directly (without LDO or DC-DC)

Harry

Re: mcxn947 external dcdc powered

neumark_engineering — Fri, 26 Sep 2025 10:07:52 GMT

How to use DCDC and disable the LDO regulator on an MCXN947VNLT (100 pin device)

When we connect VDD_LDO_CORE pin (13) to VDD_Core (12) as mentioned in [UG10101/figure8], this will destroy the core! Reason: Pin 13 has multifunctional use: VDD_LDO_CORE/VDD/VDD_P2

DCDC will not work, the Core voltage will exceed the limits!

When we left pin 13 floating, DCDC is working fine, but the question is:

How to connect this pin correctly : OPEN/VDD/GND ?

Regards, Helmut Neumark

Re: mcxn947 external dcdc powered

SaiKhamHein — Thu, 26 Mar 2026 03:00:41 GMT

I also have the same issue and later realized that on 100 pin device, it is a VDD pin. So connect it to the VDD