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Is the A10/A20 GPIO 5V Tolerant ??

Started by PathFinder, March 10, 2014, 12:47:17 pm

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i searched but i didn't found anything about this issue !

is there any reference for this issue ?




any official ref or datasheet ?

i ask because i found some sample in chines websites ,such as drive 16x2 lcd (work with 5v) and also 1-wire ds18b20 with pullup res in data pin to 5v !

if gpio not 5v tolerant , then it will be damage ! how that works ?


If there are internal clamp diodes, then the pins are some kind of "tolerant". You would just need a current limiting resistor. I have seen an official Atmel application note where the put 230Vac "directly" to a MCU pin, just with a resistor (>1Mohm).
Another possibility is a voltage divider (for inputs).

Some LCDs are able to be supplied be 5V and 3V3. You can also Supply them with 5V but give them 3V3 on their IOs. Depends on the LCD...

Don't think that anyone will take more pains for his answer, as you took for your question.


3.3v logic have the same voltage threshold as 5v ( <0.7  > 2.0v)
A 3.3v output can directly drive a 5v input.

I've just looked at the a20 datasheet, and it says Vih max is 3.6v. So you should be able to use a serial resistor to drive a 3.3v pin from 5v.

There also exist voltage convertors.