Pimoroni Automation hat maximum voltage

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1

Dear all
I want to monitor a remote Solar system using the Pimoroni Automation hat (mini).

Yet i’m not sure the HAT will survive.
According the research i did on the hat the maximum voltage seems to be 25.85V
GitHub - pimoroni/automation-hat: Python library and examples for the Pimoroni Automation HAT, pHAT and HAT Mini

But my system is going at least to 28.5 (solar system with 24 V nominal, LiFePo4 battery, with up to 28.8V while charging)
So is this voltage going to “destroy” the HAT?

I know i can build a voltage divider with resistor , enter the HAT with lower voltage and recalculate in SW the proper voltage, but i would like to avoid that.

Thank you!
Alessio

2

The way I read it, the 25.85 is the max voltage that can be read by the 24V tolerate ADC channel. That’s what the reading will top out at.

To see it that will cause damage, you’ll likely have to have a look at the schematic, and maybe do some math. Calculate what voltage you’ll be getting at the AD1 signal point of the voltage divider.

automation-hat.sch (shopify.com)

Then see if that will damage the ADS1015 that is on the Automation Hat.

Ultra-Small, Low-Power, 12-Bit ADC with Internal Reference (Rev. C) (adafruit.com)

It looks like that voltage can be (–0.3 to (VDD + 0.3)). If I’m reading that right, it’s 3.3V + 0.3 for 3.6V max. VDD is 3.3V according to the Automation Hat schematic.

Vadc = Vin * (120/(120+820))

Vadc = 3.67V with a Vin of 28.8V

If I got all of the above right, your over the max tolerable input voltage.

Sorry for all the edits, I got sidetracked, and had to backtrack and fix what I had originally posted.

3

Thanks a lot for your detailed explanations and research!
i will build a voltage divider and go in wht that so i can be safe.
Regards
Alessio

1 Like
4

I’m a retired electronic technician. That makes things easier sometimes. It makes understanding a schematic a lot easier, that’s for sure.