# "Antizener" device

A Zener diode normally starts conducting current when the voltage applied across its terminals rises over a certain threshold, called the Zener voltage. After this threshold the current keeps increasing.

Is there an electronic device / component which stops conducting current if the voltage goes above over a certain voltage? Or a circuit (simple as a Zener diode) with this function?
I know that will be unlikely to conduct an infinite current at zero voltage.

• Specifically voltage? Not a single discrete device. Well, there is a JFET or other depletion mode device but those are 3 terminal. Commented Jun 11, 2021 at 14:09
• How can this work? If the device is conducting, then the voltage on it is ~zero, so how can it go higher? Commented Jun 11, 2021 at 14:10
• With two (or more) devices sure. One single? An PTC behaves slightly in the way you describe, low ohmic at low voltage and higher (but in no way fully off) at high voltage. Commented Jun 11, 2021 at 14:11
• MOV? TVS? Crowbar? Active clamps? PTC? Fuse? Active current limiter or CC source. Commented Jun 11, 2021 at 14:11
• This older case has some easy to build circuits you maybe could use: electronics.stackexchange.com/questions/435418/… At least one of them does something which resembles what you described.
– user136077
Commented Jun 11, 2021 at 14:16

It's not too hard to design a circuit that opens up (to some finite voltage) if the input exceeds some limit and "passes through" lower voltages, but such a circuit will not be as simple as a single device or two unless someone has already integrated it onto a chip.

I'm assuming it would essentially require three terminals (one to sense the voltage and two more for current in and out) rather than two terminals like the Zener ('Zeenah' if you want the more Germanic pronunciation, though Zener was born in the US) diode.

Note that such diodes above around 5-6V depend primarily on the avalanche effect, not the Zener effect (and it was not discovered by Clarence Melvin Avalanche).

Such an "AntiZener diode" (circuit) can be made by two elements in series - an opposing diode and opposing voltage source.

The name of this circuit is "diode limiter".

“I know that will be unlikely to conduct an infinite current at zero voltage”

But a crowbar after a fuse will conduct all the current at any voltage. (Limited by loop resistance)

Please be more specify on what protection is needed and why.