Zener diodes are used for a range of applications, including:
- Voltage regulation
- Voltage reference
- Surge suppression
- Switching applications
- Clipper circuits
It is possible to use a Zener diode to create a stabilised low-ripple output voltage under variable load current conditions. When a suitable current limiting resistor is used to pass a minor current from a voltage source through the diode, sufficient current will be conducted to maintain the required voltage drop. As the load value is altered, the average voltage output also changes. However, the addition of a Zener diode can produce an even voltage output.
With that being said, it should also be noted that Zener diodes may occasionally produce electrical noise on the DC supply as they work to steady the voltage. This is fine in the majority of applications, but adding a high value decoupling capacitor to the output of the diode can rectify the problem by providing extra smoothing.
As Zener diodes can operate in the reverse bias condition, they can be used in voltage regulator circuits to sustain constant DC voltage output. This constant voltage can be maintained despite any variations in voltage input or load current changes.
This voltage regulator circuit comprises a current limiting resistor which is connected in series with the input voltage. The diode and the load should then be connected in parallel. The stabilised voltage output and the diode’s breakdown voltage will always be the same.