nRF52840 LDO recommendation / guidance

[MAshcraft]

Hello,

       I am preparing to develop a design using the nRF52840 and would like any guidance or consideration for an LDO usage. I have found some previous mention regarding LDO's in some of the DevZone postings - especially expressing that any input voltage transients would not produce an RF disturbance.
https://devzone.nordicsemi.com/f/nordic-q-a/35565/nrf52840-ldo-accuracy-for-japanese-rf-regulations
https://devzone.nordicsemi.com/f/nordic-q-a/587/recommend-ldo-please

      Could I receive some feedback for the below selected TI LDO part? I would be using 5V as part of a system voltage rail, and convenient to source the Nordic MCU through the 3.3V LDO.

      https://www.digikey.com/en/products/detail/texas-instruments/LP5907MFX-3-3-NOPB/3906441

      Is there any general guidance about Nordic's preferred best practice regarding PSRR or voltage ripple preferences?

Thanks,

     Matt

[Jared]

Hi,

We usually don't give any recommendations on third-party products, especially if we don't have any experience with them. Is DC/DC an alternative? We do use external DC/DC regulators on the nRF52840 DK, check the BOM list for the DK. 

       I am preparing to develop a design using the nRF52840 and would like any guidance or consideration for an LDO usage. I have found some previous mention regarding LDO's in some of the DevZone postings - especially expressing that any input voltage transients would not produce an RF disturbance.

Usually this is not a concern as we recommend pretty big decoupling capacitors on the VDD supply line( see reference design). But if some noise would be able to pass it would indeed affect the radio. But in most cases this is not a concern.

regards

Jared 

Reference design and BOM list.