Uses of Zener Diode Overview
A zener diode is a semiconductor device that conducts current in the reverse direction when a certain voltage is applied. This voltage is known as the zener voltage or breakdown voltage. When the voltage across the zener diode exceeds the breakdown voltage, the diode conducts current and maintains a constant voltage across its terminals.They are special types of diodes that can operate in the reverse breakdown region without being damaged. In this article, we will discuss the uses of zener diodes in detail.
What is a Zener Diode?
A Zener diode is a type of semiconductor diode that is designed to operate in the reverse breakdown region. Unlike regular diodes, which are designed to conduct current in only one direction, Zener diodes allow current to flow in the reverse direction when a certain voltage is reached. This characteristic is known as the Zener breakdown, and it allows Zener diodes to maintain a stable voltage across their terminals.
Zener diodes are named after Clarence Melvin Zener, an American physicist who first proposed the concept of the Zener breakdown in 1934. Today, Zener diodes are commonly used in electronic circuits for voltage regulation, overvoltage protection, voltage shifting, waveform clipping, noise reduction, temperature sensing, and current limiting.
- Zener diodes are made from a p-n junction with a heavily doped p-type material and a lightly doped n-type material.
- The heavy doping of the p-type material allows the diode to have a very low breakdown voltage, typically between 2 and 200 volts.
- The diode is designed to operate in the reverse bias mode, which means that the voltage applied to the diode is in the opposite direction to the direction of current flow.
Uses of Zener Diode: Function
When a forward one-sided voltage is applied to the Zener diode, it operates in the same way as a conventional diode. In any case, when a one-sided voltage is applied to the Zener diode, it behaves in a variety of ways.
When an opposing one-sided voltage is applied to a Zener diode, only a small amount of spilling current is allowed until the voltage is not exactly Zener voltage. When the reverse one-sided voltage applied to the Zener diode reaches Zener voltage, it begins to allow a large amount of electric flow.
A small increase in inversion voltage will now rapidly increase the electric flow. The sudden increase in electric flux causes zener breakdown. However, the Zener diode exhibits a controlled breakdown that damages the device.
Uses of zener Diode
Uses of Zener Diode as a Voltage Regulator:
One of the primary uses of Zener diodes is voltage regulation. They are used to maintain a stable voltage supply by regulating the voltage across their terminals. This makes them ideal for use in voltage regulators and voltage references. Voltage regulators are used to maintain a constant voltage output from a power supply, regardless of variations in input voltage or load current. Voltage references, on the other hand, are used as a reference voltage for other components in a circuit.
Uses of Zener Diode for Overvoltage Protection:
Zener diodes are also commonly used in electronic circuits as overvoltage protectors. They are used to protect sensitive components from damage due to overvoltage. When the voltage in a circuit exceeds a certain limit, the Zener diode conducts and shunts the excess current to ground. This protects the circuit from damage due to overvoltage.
Uses of Zener Diode for Voltage Shifting:
Another important use of Zener diodes is in voltage shifting circuits. In such circuits, the Zener diode is connected in series with a resistor and the input voltage. The output voltage across the resistor is shifted by the Zener voltage. This is useful in circuits where a shifted voltage is required, such as in power amplifiers or audio applications.
Uses of Zener Diode for Waveform Clipping:
Zener diodes are also commonly used in waveform clipping circuits. In such circuits, the Zener diode is connected in series with a load resistor and the input waveform. When the input voltage exceeds the Zener voltage, the Zener diode conducts and clips the waveform. This is useful in applications where a limited voltage range is required, such as in audio or video applications.
Uses of Zener Diode for Noise Reduction:
Zener diodes can also be used in electronic circuits as noise suppressors. In such circuits, the Zener diode is connected in parallel with a load resistor. The Zener diode conducts when the voltage across the resistor exceeds the Zener voltage, reducing the noise level. This is useful in applications where a low noise level is required, such as in sensitive electronic equipment or communication systems.
Uses of Zener Diode for Temperature Sensing:
Zener diodes can also be used as temperature sensors. The voltage across a Zener diode is temperature-dependent, and this characteristic can be used to measure the temperature of a system. The Zener diode can be used as part of a temperature sensing circuit, where the voltage across the diode is measured and converted into a temperature reading.
Uses of Zener Diode for Current Limiting:
Zener diodes can be used as current limiters in electronic circuits. When a current-limited power supply is required, a Zener diode can be used to limit the current to a safe level. This is useful in applications where the current needs to be limited, such as LED drivers or battery charging circuits.
Uses of Zener Diode: Specifications
Zener diodes vary in specifications such as nominal working voltage, power dissipation, maximum reverse current, and packaging. Some commonly used specifications include:
- Voltage Vz: The Zener voltage refers to the reverse breakdown voltage—2.4 V to about 200 V; can go up to 1 kV while the maximum for the surface-mounted device (SMD) is about 47 V).
- Current Iz (max.): Maximum current at the rated Zener voltage Vz—200 uA to 200 A).
- Current Iz (min.): Minimum current required for the diode to break down—5 mA and 10 mA.
- Power rating: The maximum power the Zener diode can dissipate; given by the product of voltage across the diode and the current flowing through. Typical values are 400 mW, 500 mW, 1 W, and 5 W; for surface mounted, 200 mW, 350 mW, 500 mW, and 1 W are typical.
- Voltage tolerance: Typically ±5%.
- Temperature stability: Diodes around 5 V have the best stability.
- Package: Leaded devices and the surface mount either as discrete devices or within integrated circuits.
- Zener resistance (Rz): The diode exhibits some resistance as evident from the IV characteristics.
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Uses of Zener Diode: Things to Remember
- A basic PN junction diode forms under the combination of p-type and n-type semiconductor materials. A PN junction is formed when donor impurities are doped on one side of a semiconductor crystal and acceptor impurities are doped on the other.
- A Zener diode can be used as a voltage regulator or a voltage reference in a DC circuit. The major benefit of a Zener diode is that the voltage across it remains constant despite a larger variation in current. As a result, a Zener diode can be used as a voltage regulator or a constant voltage device.
- Zener diodes are used as a constant voltage source or a voltage reference in power supply and many other circuits. The only requirements are that the input voltage exceeds the Zener voltage and that the series resistor has a minimum value that allows the device to conduct the maximum current.
- A Zener diode can be utilized in a circuit containing an AC input source, which is distinct from a conventional PN diode clamping circuit. The diode may be used to limit the peak of the output voltage to Zener voltage on one side of the sinusoidal waveform and to around 0V on the other.
- Android-based projects are becoming more popular as smartphones become more prevalent. Bluetooth-enabled devices are being used in these projects. The operation of these Bluetooth devices needs a voltage of around 3V. A Zener diode is used to provide a 3V reference to the Bluetooth device in such cases.
- Zener diode is an important topic from the standpoint of the class 12 board exam. It is part of chapter 14 named ‘SEMICONDUCTOR ELECTRONICS: MATERIALS, DEVICES AND SIMPLE CIRCUITS'. The chapter briefs us about the seed of the development of modern solid-state semiconductor electronics.