ESP8266 Community Forum

Posted: **Fri Aug 14, 2015 12:19 pm**

also looking at the adafruit spec sheet ..
http://www.adafruit.com/datasheets/ESP8266_Specifications_English.pdf

page 15 .. Input high voltage is specced at 3.6V

so now, I am not sure whether 5v compatible or not. anyone got an actual data sheet link mentioning the snapback circuitry, I forgot where I saw that now.

Posted: **Fri Aug 14, 2015 3:48 pm**

I'm not great at electronics ... but if we look at at Table 3 in Section 2.2 in this official datasheet ...

http://bbs.espressif.com/download/file.php?id=520

Do we not see the max voltage as being 3.6V?

Neil

Posted: **Fri Aug 14, 2015 4:17 pm**

Yes, but I think is mentioning what is written after the Table 6 in 3.1.1 :

Code: Select all

All digital IO pins are protected from over-voltage with a snap-back circuit connected between the
pad and ground. The snap back voltage is typically about 6V, and the holding voltage is 5.8V. This
provides protection from over-voltages and ESD. The output devices are also protected from
reversed voltages with diodes.

But we should NEVER rely on that, since this will short circuit the output from the other devices ...

Posted: **Fri Aug 14, 2015 4:26 pm**

Page 17 of that same document.
They are not 5V tolerant it is simply noted that

All digital IO pins are protected from over-voltage with a snap-back circuit connected between the
pad and ground. The snap back voltage is typically about 6V, and the holding voltage is 5.8V. This
provides protection from over-voltages and ESD. The output devices are also protected from
reversed voltages with diodes.

This implies then that the accidental application of 5V is not going to be disastrous .

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