The power-efficient of nRf52840 when using the external supply

[Hsu]

Hi Sir,

If we would like to supply the external device through VDD = 1.8V when VDDH = 2.5V.

What is power efficient in nRF52840 when VDD = 1.8V when VDDH = 2.5V?

Thank you.

BRs, Han

[Simonr]

Hi Han

I'm struggling to understand what exactly you mean, but I assume you are referring to what regulator configuration will be most efficient in your scenario (Please specify if this is not the case). If you enable the DCDC regulator the PMU (Power Management Unit) will automatically switch between what regulators to use to be the most power efficient.

Best regards,

Simon

[Hsu]

Hi Simon,

Sorry to make you confuse. We just want to know the power-efficiency ratio for internal LDO and DCDC mode

The power-efficiency ratio = Pout/Pin 

If the VDDH = 2.5V, and VDD=1.8V

could we say the power-efficiency ratio is 1.8/2.5=72%?

Thank you.

BRs, Han

[Simonr]

Hello Han

Ideally, it would be Pout/Pin for the DCDC, but the regulators draw current as well, so it will be somewhat lower than this. For the LDO the current will be approximately the same current in as out. It should not be necessary to worry about this though, due to the PMU.

Best regards,

Simon