Will 3.6 volts fry my pyboard

The official pyboard running MicroPython.
This is the reference design and main target board for MicroPython.
You can buy one at the store.
Target audience: Users with a pyboard.
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rhubarbdog
Posts: 166
Joined: Tue Nov 07, 2017 11:45 pm

Will 3.6 volts fry my pyboard

Post by rhubarbdog » Tue Apr 16, 2019 4:56 pm

I have a chip i plan to use in my project. It's a 5 volt device but inputs react as documented to voltages as low as 2 volt. The possible problem is the output pins appear to output 3.6volt. Will that damage my pyboard.

ThomasChr
Posts: 114
Joined: Sat Nov 25, 2017 7:50 am

Re: Will 3.6 volts fry my pyboard

Post by ThomasChr » Tue Apr 16, 2019 5:45 pm

Digital input of the Pyboard are 5V tolerant. So no problem here.
The analog inputs are not, so beware.
But I'm pretty sure that 3.6V won't damage anything...

chrismas9
Posts: 104
Joined: Wed Jun 25, 2014 10:07 am

Re: Will 3.6 volts fry my pyboard

Post by chrismas9 » Tue Apr 16, 2019 11:39 pm

Not all STM32 pins are 5V tolerant. The DAC pins PA4 and PA5 are not 5V tolerant even in digital IO mode. On some STM32s other pins are not (sometimes PA3 and maybe more). Always check the data sheet.

Most analog pins, eg PA0, are 5V tolerant at reset and in digital IO mode. In ADC mode the inputs are only 3.3V rated because they are disconnected from the digital input protection circuit and connected directly to the ADC. This is to prevent leakage current in the digital IO affecting high impedance analog inputs and to stop excessive power consumption.

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