Unlike normal diodes, which allow only forward current, Zener diodes will allow a current to move in reverse when voltage exceeds a specified value, preventing breakdown of the diode. Because of this ability to reverse a portion of the current, Zener diodes offer several advantages in a circuit that normal diodes don't. The idea behind the reverse current used in this diode was proposed by Dr. Clarence Melvin Zener in 1934.
The ability of the Zener diode to control and reverse part of the current flowing through it means it can be used to regulate and stabilize the voltage in a circuit and prevent problems that can occur when the supply or load voltage varies. Circuit designers can use the Zener voltage of the diode to exactly regulate and stabilize the voltage in the circuit.
Size and Expense
Zener diodes are very small, so they can be used in many small electronic devices, such as handheld devices and cell phones. They also can be used in smaller circuits that would not work with any larger form of current regulation. Zener diodes are less expensive than other diodes used in these devices. This can cut the cost to produce a device such as a television or computer, lowering consumer costs.
Zener diodes have a very high performance standard, often more than the electronic device they are placed in needs to operate at maximum efficiency. These diodes are equipped to handle a higher voltage than the standard operating voltage, so they are able to handle more power. These diodes will still operate at standard voltage, but will not blow out if the voltage is still under their threshold. They are also small enough to allow current to flow quickly through their circuits.
Compatibility and Obtainability
Zener diodes, due to their lower cost and greater control, are commonly used in electric devices. They are also compatible with most systems, so they are a preferred method to regulate voltage. They are also used in other applications, such as in solar panels. Though these diodes don't often get damaged due to their current controls, they can still blow out if the current exceeds what they are equipped to handle. If this were to happen, the SCR would also likely blow out and both elements would need to be replaced. Luckily, Zener diodes are fairly easy to obtain due to their common use and low cost.