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Open drain output max voltage
Posted: Tue Dec 08, 2020 2:41 pm
by iamflimflam1
Hi All,
I've set the output mode of the GPIO pin to open drain and was wondering what is the maximum voltage I can pull up to?
Thanks
Chris
Re: Open drain output max voltage
Posted: Tue Dec 08, 2020 10:07 pm
by becorey
Probably 3.6V, that is the absolute maximum rating of any power pin on the esp32. For safety margin, you shouldn't go to 3.6V, 3.3V is safe.
If you need to control a higher voltage you need to use a mosfet or transistor.
Re: Open drain output max voltage
Posted: Wed Dec 09, 2020 1:48 pm
by iamflimflam1
I can't find many (any) details on the output drivers.
I thought that unless there are protection diodes that would take the voltage back to the supply rails you should be safe pulling up an open-drain output to a higher voltage as it won't be connected to anything when the output is off?
Re: Open drain output max voltage
Posted: Thu Dec 10, 2020 1:46 am
by ESP_Sprite
iamflimflam1 wrote: ↑Wed Dec 09, 2020 1:48 pm
...unless there are protection diodes that would take the voltage back to the supply rails...
The ESP has internal ESD protection snapback devices that essentially work like diodes taking the voltage back to the power rails.