Hello! I want to use a zener diode to protect the input pin of a microcontroller from overvoltages, but I really don't know which one to choose.
The pin is fed by a 2200 ohm resistor, and after that, the zener to ground.
I attached 2 sections of datasheets about 2 different zeners, they have very different values of Zzt, but i don't know which one is "better"
I don't really understand in practice what the Zzt value means...
For what I think, it's the resistance while it's in the breakdown region, so lower is better
is this right?
any advice is greatly welcome!
This is because the differential impedances Zzt have been measured at different break-through currents Izt. As larger Izt, as lower Zzt ; for relatively low currents the break-down characteristic gets steeper with rising current. I think the 2 diodes are comparable.