Running ESP32 at 2.8V

p-rimes
Posts: 72
Joined: Thu Jun 08, 2017 6:20 pm

Running ESP32 at 2.8V

Postby p-rimes » Fri Jun 15, 2018 11:49 pm

Cool part: Microchip Technology MIC5356-MGYML-TR
https://www.digikey.ca/product-detail/e ... ND/5700737

Dual linear voltage regulators @2.8v and @1.8v, 500ma current each, $0.30 (cheaper than my current single 3.3v reg!)

In the interests of power savings, can anyone recommend using (or not using) this part with an ESP32 module? I already have a SMPS 5v supply in the mix, which would be the supply for this reg.

WiFive
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Joined: Tue Dec 01, 2015 7:35 am

Re: Running ESP32 at 2.8V

Postby WiFive » Sat Jun 16, 2018 12:14 am

Will you realize power savings by dropping more voltage across a linear reg?

p-rimes
Posts: 72
Joined: Thu Jun 08, 2017 6:20 pm

Re: Running ESP32 at 2.8V

Postby p-rimes » Sun Jun 17, 2018 4:02 pm

Honestly, I'm not sure. I know a bit about linear electronics, and I did expect extra loss on the LDO. But for all that the ESP32 is doing (RF, internal amplifiers, internal voltage domains, etc), I wasn't sure what the pros/cons of a reduced voltage are (if you just treat it as a linear black box/load with 500ma draw, or as something like a diode, then I agree it's probably not a good idea).

I guess I don't have a good mental model for digital circuit design; I'm not really sure what's going on between 3.3V and GND inside an IC (especially without the power curves section on a datasheet). When I hear "non-linear" devices, I guess I thought that could also mean... worse than linear?

What about in the case of an ideal 2.8V source vs. a 3.3V source (not worrying about LDO), any reason to run at 2.8V (or any other voltage than 3.3V)?

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krzychb
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Re: Running ESP32 at 2.8V

Postby krzychb » Sun Jun 17, 2018 6:11 pm

Hi @p-rimes,

Running a chip at reduced voltage means reducing power consumption by the chip.
This is done to e.g. run the chip for a longer time on a battery.

The overall power consumption will not be reduced by dropping the voltage (and dissipating power) on a linear voltage regulator. What will be saved on the chip will be lost on the linear voltage regulator.

Instead I would use a switching regulator.

Check Advantages / Disadvantages under What is the Difference Between Linear and Switching Regulators?

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