Power supply voltage for nrf52 SoC

[Lakerno]

Does nrf52 SoC consumes the same current at different supply voltages(assuming similar operating conditions) ? For eg what is the difference between operating the nrf52 at 1.8V or 3V for current consumption?

In my design I am using a li-ion battery to power NRF52 SoC at 1.8V. Some of the other logic require 3V. So does it make sense to use 1.8V for NRF52, from a power savings point of view??

[FormerMember]

Since the core system uses 1.3V, the supply voltage is regulated through either a Linear (LDO) or a switching regulator (DC-DC). DC-DC requires an additional inductor.

In case of a LDO, there the power dissipated is proportional to the difference between the input and output voltage and also proportional to the drawn current.

If you want to use the LDO, then it makes sense to use 1.8V supply. The pro is that you need not use the inductor. The con is that the power consumption will be higher than using DC-DC.

If adding an inductor is not an issue, the DC-DC will give greater power saving. And the supply voltage doesn't matter. And the GPIO voltage will now be 3V, compatible with other components.

[Lakerno]

I am using DC-DC converter configuration from the reference schematic. I have additional external power managment IC with an integrated DC-DC output which I want to use for powering nrf52. So there is 2 DCDC converters, one is the external DCDC converter from my PMIC and the second one is the internal DCDC converter in the NRF52 chip.

now, my question is if I use 1.8V supply to power NRF52 from the external DCDC converter OR if I use a 3V external DCDC converter, IS there any difference in the current consumed by NRF52? If the current is the same, then I can use the 1.8V to save some battery.

[FormerMember]

I can see 3 situations which I'll list in ascending order of power consumption I think it would result in:

1. Using the 3V supply with DC-DC. The DC-DC of nrf52 is optimized for itself. The DC-DC goes into a refresh mode when the load current is low.

2. Using 1.8V supply with DC-DC. Here your external DC-DC and nrf52's internal one are used.

3. Using 1.8V supply with LDO. There will be 0.5V drop over the LDO resulting in some power loss. But not as much as when 3V supply is used.

[Lakerno]

? I want to know, what is the current draw in each case.

[FormerMember]

You can find the values for the CPU and radio power consumption with 3V supply using DC-DC (situation 1) and LDO in the datasheet. With 1.8V supply the values are not provided in the datasheet, but I'm guessing it'll be between these two.