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What is a Zener Diode?

What is a Zener Diode?

Zener diodes are a special kind of diode which permits current to flow in the forward direction. What makes them different from other diodes is that Zener diodes will also allow current to flow in the reverse direction when the voltage is above a certain value. This breakdown voltage is known as the Zener voltage. In a standard diode, the Zener voltage is high, and the diode is permanently damaged if a reverse current above that value is allowed to pass through it. Zener diodes are designed in a way where the Zener voltage is a much lower value. There is a controlled breakdown which does not damage the diode when a reverse current above the Zener voltage passes through a Zener diode.
Types of Zener Diodes
There are many different kinds of Zener diodes. Topdiode supply many of the most common types categorized by power dissipation, nominal working voltage, forward (drive) current, forward voltage, packaging type and maximum reverse current. The most common values for nominal working voltage are 5.1 V, 5.6 V, 6.2 V, 12 V and 15 V. Forward (drive) current can have a range from 200 uA to 200 A, with the most common forward (drive) current being 10 mA or 200 mA.
Applications for Zener Diodes
Zener diodes can be found in several applications. Some of these are: voltage stabilizers or regulators (in shunt mode), surge suppressors for device protection, peak clippers, switching operations, reference elements and in meter protection applications. The constant reverse voltage of a Zener diode renders it a very useful component in regulating the output voltage against variations in the load resistance or variations in the input voltage from an unregulated power supply. The current through the Zener diode will change in order to keep the voltage within the threshold limits of Zener action and the maximum power that it can dissipate.

Zener Diodes in Topdiode

Zener Diode 

Power dissipation


Voltage Range


BZX55C2V7~47V DO-35



BZV55C2V4~47V LL-34


1000mW, 1W

1N4729A~1N4756A DO-41



DL4728A ~DL4764A LL-41