AVR-Chat

David VanHorn wrote:
>> If the data rate isn't too fast and the latchup current of overdriven
>> inputs is specified, you can use a single series resistor between output
>> and input. Even if the latchup current isn't specified, you can still gain
>> some confidence by abusing a chip with 10-20mA overdrive and see if it's
>> tolerant.
> 
> Confidence in what, exactly?
> 
> If there isn't enough load to pull that current back out of the rail, you
> end up raising the 3.3V rail out of spec.

Latchup only happens over a certain thresh-hold, so if you're confident
that your overdrive is always much lower than that, then problem solved.