nRF54LM20A High Voltage Mode?

[sasodoma]

Hi,

I know that the nRF54LM20A was just announced but since it has USB support I am considering it as an option to replace the nRF52840 in the future. Looking at the preliminary datasheet, it seems that an important feature is missing though. The nRF52840 has a High Voltage mode that allows it to be powered directly from the USB port to which it is connected, which to me seems like an awesome feature for a USB IC. The 5V compatibility also enables it to be powered directly from a Li-ion battery and still be very power efficient due to the DC-DC converter. The nRF54LM20A appears to not have a High Voltage mode, so I'm wondering if it is already known, what the recommended way of powering the device from USB will be?

Thank you and best regards,
Sašo

[Simonr]

Hi Sašo

The nRF54LM20A does indeed support USB. It has a separate USB regulator (USBREG) that's documented in section 5.9.1 of the datasheet. A 5V USB supply must power the VBUS pin when using the USB peripheral. The device has a dedicated internal voltage regulator for converting the VBUS supply to 3.3V for the USB signaling interface.

Best regards,

Simon

[sasodoma]

Hi Simon!

Thank you for your reply. I'm aware that the VBUS pin only powers the USB interface. On the nRF52840 board, there was a VDDH pin, which could take up to 5.5 V, and power the whole chip directly from USB. As far as I can tell this isn't possible on the nRF54LM20A, so I'm wondering wether the intention was to always need an external voltage regulator for VDD or perhaps the high voltage mode is present but not yet tested an thus not mentioned in the Preliminary Datasheet?

Best regards,
Sašo

[Simonr]

Hi

Correct, the nRF54LM20A does not have a VDDH mode, so you will need a regulator of some sort. An nPM1300 for instance can work like a power management unit in this case.

Best regards,

Simon

[sasodoma]

Thank you, this clears it up.

Best regards,
Sašo