Regulator Circuitry Dying

Hello,

I am working on a project which requires running an Electron off of a 12V lithium battery pack through the Vin pin. So far, with the PCB i have created, the circuitry works fine when running off of a separate 12V supply, but when running off of the 12V lithium battery, the Electron’s PMIC circuitry fails and stops working. The electron will run off of the included 3.7V lithium battery, but will no longer run off of the Vin pin or USB port.

During testing, the voltage on the battery pack was 13.3V. I understand this is higher than Particle’s recommended input voltage, but according to the PMIC’s datasheet, falls well within the maximum voltage range.

Has anyone else had success running an Electron off of a similar battery or similar issues with the PMIC circuitry?

Thanks

AFAIK there is a 12V safety limiter that just switches off Vin when it detects voltages greater than 12V.

@mohit The BQ24195 PMIC chip on the Electron has a maximum voltage input rating of 17v DC.

I did a quick read through of the datasheet but didn’t find any immediate reason it might be limited to 12v input instead of 17v but figured I would ask why it’s limited to 12v in the Electron documentation.

Thanks!

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Will the Electron automatically switch Vin back on when voltage goes below 12V or does it have to be reset manually? My Electron will not take input from Vin or USB even after removing all power

I expected it to switch back on automatically, but since you see different behaviour I could be mistaken
@BDub, any insight how Vin behaves on the Electron when supplied with more than 12V?


The absolute max. ratings are here (17V on Vin - almost “guaranteed” death beyond that :sunglasses:)
https://docs.particle.io/datasheets/electron-datasheet/#absolute-maximum-ratings-sup-1-sup-i-class-icon-attention-i-

I was well below the 17V max rating. And on a side note, with the 3.7V lithium battery plugged in for power, I am able to upload and run code through USB. So the microcontroller is working fine, but not the PMIC.

That’s an interesting behaviour.

You are correct, the PMIC is rated at 17V max. We have tested the Electron to operate at 17V as well. Due to the size constraints of the PCB, there isn’t enough thermal dissipation available. This is the reason we have capped the max input voltage to 12V so that the operation is guaranteed to run cooler. You can definitely run it above that voltage but you may run into overheating. Having said that, the PMIC has an inbuilt thermal shut-off, so it won’t destroy the Electron.

What is the ampere rating and max discharge rate of the 12V lithium battery pack? The Electron will consume transient peak currents of up to 1900mA @3.8V

Regards,
Mohit

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