# Zener diode

1. Aug 20, 2015

### Amrutha.phy

Why doesn't the voltage vary beyond breakdown voltage in zener diode?

2. Aug 20, 2015

### LvW

In fact, it does vary. The finite slope of the Iz-Vz characteristic is expressed in form of a dynamic (differential) resistance rz which assumes rather small values (some ohms).
More than that, this value (the slope) is not constant but varies with the current Iz.

Last edited: Aug 20, 2015
3. Aug 20, 2015

### Jeff Rosenbury

It does.

There is a voltage-current curve, it just has a sharp knee.

The reason the knee is so sharp is because the Zener effect is based on tunneling.

4. Aug 20, 2015