quantifying PMIC overhead

[bios-bob]

actually a general question, though i'm working with the nPM2100 EK....

assume my target MCU operates "most efficiently" when supplied 1V8 -- expressing overall energy consumption in Joules....

but i'm using a 3V battery as my power source, hence i'll need to buck my voltage down to 1V8....

assuming i'm using a PMIC (like the nPM2100), how should i best capture the "real energy" consumed by this configuration....

using (say) a PPK, do i measure current "upstream" near my 3V source??? (or maybe i use the PPK to source 3V ???)

said another way, should i really be multiplying the Coulombs reported by the PPK by 3V to get my true energy consumption in Joules???

i have similar boards to the nPM2100 EK from other vendors and want to ensure i'm truly making an "apples-to-apples" comparison....

[bios-bob]

my goal is to quantify overall energy efficiency in my target system doing "something" typical -- for instance, BLE advertising at a 1s interval....

i want to do A-B comparisons -- with vs without the PMIC, Nordic's PMIC versus someone else's, etc....

given that the nRF54 has an onboard DCDC, will i do better sending 3V directly to the MCU or should i send it to a PMIC which will output 1V8 directly into the MCU???

[Einar Thorsrud]

Hi,

The nRF54L15 will always use the internal DCDC as some internal voltages are lower. Also, note that using an external regulator or not is not just a matter of efficienty, as the GPIO voltage will be the same as the VDD voltage, and this along with other factors such as potentially a rechargable battery, need for fule gauging etc, determine what type of PMIC you should use or if you do not need any at all.