5V TTL input

[thommagn]

Posted on June 13, 2013 at 16:56

Hi,

I'm using a stm32f4 discovery board. The data sheet says that my pins are 5V restistant. 

I have a device that outputs 5V ttl and I want to read this signal. It works, but does it reduce the lifetime of the processor? Can it simply break down because of this?

// Tom

[Tesla DeLorean]

Posted on June 13, 2013 at 18:23

No, the FT pins should not permit back flow of current onto the primary 3V rail, and the IO cell is designed to receive voltages exceeding 3V (or VDD) up to 5V.

Where damage might occur is if you attempt to drive the pin high or low against this ~5V signal level, and whatever current the external source can supply.