A Zener diode is a specialized type of diode that is designed to operate in a reverse breakdown region, called the Zener breakdown, to maintain a nearly constant voltage across its terminals. It is used primarily for voltage regulation and protection in electronic circuits. When the Zener diode is reverse-biased, and the applied voltage exceeds its breakdown voltage (known as the Zener voltage), it starts conducting. It maintains a constant voltage drop across its terminals. This unique characteristic makes Zener diodes useful in voltage regulation, voltage reference circuits, and as voltage limiters. The symbol for a Zener diode is similar to a standard diode symbol with a bend in the cathode line.
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The figure below displays Zener Diode Symbol.
