In this blog, we will delve into the world of TVS and Zener diodes, exploring their functionalities, operational principles, and the key differences that set them apart.

What is a TVS Diode?

A TVS Diode acts as a protector for electronic circuits. It protects delicate components from damaging voltage spikes and electrostatic discharge (ESD) incidents. 

Are TVS Diodes Bidirectional?

There are two primary configurations available for TVS diodes:

• Unidirectional TVS Diodes: These are only capable of conducting electricity in one direction. They are usually applied in situations where a single polarity (positive or negative) is the source of the transient voltage danger.
• Bidirectional TVS Diodes: TVS diodes that carry current in both directions, irrespective of polarity, protect against voltage spikes.

Depending on the particular application and the expected voltage transient risks in the circuit, unidirectional or bidirectional TVS diodes should be chosen.

What is a Zener Diode?

A Zener Diode serves as a voltage regulator as opposed to a TVS diode. It successfully regulates voltage inside a circuit by allowing a certain, predetermined voltage to pass through the diode in the reverse bias direction. 

Video related to Zener Diodes

Can Zener Diode be Used as Rectifier?

Yes, Zener diodes can function as simple rectifiers. In this application, they permit forward bias current flow but obstruct reverse bias current flow (beyond the breakdown voltage). This makes it possible to convert AC electricity to pulsating DC voltage, albeit the efficiency may not be as good as it could be when using rectifier diodes specifically for that purpose.

What is TVS Diode Used for?

A TVS (Transient Voltage Suppression) diode is used for protecting electronic circuits from transient voltage spikes. Here are its primary uses:

• Surge Protection: Protects circuits against spikes in voltage brought on by power changes, lightning, and other sources.
• Electrostatic Discharge (ESD) Protection: Provides defense against potential harm caused by electrostatic discharge incidents that may arise when handling or using electronic equipment.
• Inductive Load Switching: By switching inductive loads, such as motors and relays, inductive load switching guards against voltage spikes.
• Data and Communication Lines: Preserves signal integrity by protecting data and communication lines from transient voltages.
• Automotive Electronics: Because of the nature of the vehicle's electrical environment, voltage spikes frequently occur in automotive systems, where automotive electronics provide strong protection.

All things considered, TVS diodes are essential for preserving the robustness and longevity of electronic systems by shielding delicate components from transient voltage damage.

What is a Zener Diode Used for?

A Zener diode is a kind of semiconductor device that, upon reaching a specified, planned reverse voltage (sometimes referred to as the Zener breakdown voltage), permits current to flow in the opposite direction. These are its main applications:

• Voltage Regulation: To keep an output voltage steady even when the input voltage or load conditions change, zener diodes are frequently utilized as voltage regulators. They give circuits a reference voltage.
• Voltage Clamping: To shield delicate components from high-voltage transients, Zener diodes clamp the voltage in over-voltage safety circuits to a predetermined value.
• Voltage Reference: In many different applications, including digital-to-analog converters (DACs) and analog-to-digital converters (ADCs), zener diodes provide accurate voltage references.
• Waveform Clipping: To ensure that signals do not exceed predetermined amplitudes, signal voltages are clipped or limited to specified levels using Zener diodes in signal processing.
• Switching Applications: Zener diodes are employed in circuits that require a certain threshold voltage to change the state of the circuit.

All things considered, Zener diodes are crucial parts of electronic circuits that need safety, reference, and voltage stabilization.

TVS Diode vs Zener Diode

Although Zener diodes and TVS diodes are both used in many electrical circuits, their main purposes and features are very different. The main differences are summarized in the following table:

How TVS Diodes Work?

Transient Voltage Suppression (TVS) diodes clamp excess voltage to a safe level, shielding electronic circuits against transient voltage spikes. This is how they function:

1. Normal Operation: The TVS diode has a high impedance and is non-conductive under typical working circumstances. It doesn't impede the circuit's ability to operate normally.
2. Transient Event: The TVS diode rapidly transitions from a high-impedance state to a low-impedance state (usually in nanoseconds) when a transient voltage spike, such as a surge from lightning or an electrostatic discharge (ESD), surpasses the breakdown voltage of the diode.
3. Clamping Action: The TVS diode redirects excess transient energy away from the protected circuit by clamping the voltage to its breakdown voltage while it is in the low-impedance state. By doing this, the voltage spike is kept from harming delicate components.
4. Energy Dissipation: To safeguard the circuit against overvoltage situations, the TVS diode absorbs and releases the energy from the brief voltage spike as heat.
5. Return to Normal: The TVS diode goes back to its high-impedance condition and is prepared to fend off more transients once the transient event has passed and the voltage has stabilized.

In general, TVS diodes ensure the longevity and dependability of electronic devices by offering quick and efficient protection against voltage spikes.

How Does a Zener Diode Work?

For a Zener diode to function, the voltage across it must reach a certain reverse breakdown value, sometimes referred to as the Zener voltage. Only then can current flow in the opposite direction. The following describes a Zener diode's operation step-by-step:

1. Forward Bias Operation: A Zener diode functions like a standard diode when it is forward biased, which is when a positive voltage is supplied to the anode about the cathode. This allows current to flow freely with a typical forward voltage drop, which for silicon diodes is approximately 0.7V.
2. Reverse Bias Operation: Upon applying a reverse voltage, or a negative voltage to the anode in comparison to the cathode, the diode first inhibits current flow in the same manner as a typical diode. Its high resistance makes it impossible for current to flow through.
3. Zener Breakdown: The diode enters the Zener breakdown zone when the reverse voltage rises to the Zener voltage (Vz). At this moment, the diode begins conducting current in the opposite direction and its resistance reduces dramatically. The diode is not harmed by this controlled breakdown process.
4. Voltage Regulation: Regardless of changes in the reverse current, the voltage across the Zener diode in the breakdown area stays almost constant at the Zener voltage. Zener diodes are perfect for voltage regulation applications because of this feature. Even if the load or input voltage fluctuates, they can maintain a steady output voltage.
5. Clamping and Protection: By clamping the voltage to the Zener voltage, Zener diodes can also be utilized to safeguard circuits against over-voltage situations.

In conclusion, Zener diodes are helpful for voltage regulation, reference voltage generation, and over-voltage protection in a variety of electronic circuits because they use their controlled breakdown ability to maintain a constant voltage across them.

How to Connect TVS Diodes?

While connecting TVS diodes is quite simple, there are a few things to remember to make sure they work properly:

1. Identify what to protect: Choose the line (power or signal) that you wish to protect first.
2. Match the diode: Select a TVS diode whose voltage rating is higher than the typical operating voltage of your circuit but still low enough to trip during a surge.
3. Diode placement: The TVS diode should ideally be positioned as close as feasible to the connector that the voltage spike could potentially enter. By doing this, the surge's path before it is diverted is shortened.
4. Mind the path to the ground: For best results, connect the specified ground terminal of the TVS diode straight to the ground plane of the circuit.
5. Separate lines: Steer clear of running signal traces next to potentially surge-carrying traces. Directly place the TVS diodes on each line that has to be protected.

To put it another way, think of the TVS diode as a security guard. By positioning it near the connector (entry) and providing a clear route to the ground (exit), they may act swiftly to divert any potential problems (surge current) from the valuables (circuit components).

How to Test Zener Diode?

A Zener diode must be tested to make sure it operates as intended and to confirm its breakdown voltage. Here is a basic multimeter procedure:

1. Set Multimeter: To measure the breakdown voltage of the Zener diode, set your multimeter to the diode testing function (typically indicated by a symbol that looks like a diode with an arrow) or the appropriate voltage range.
2. Forward Bias Test: Attach the multimeter's positive lead, or red probe, to the Zener diode's anode (positive terminal), and its negative lead, or black probe, to the cathode (negative terminal). If the diode is operating correctly in this forward bias setup, the multimeter should show a voltage drop of about 0.7 volts.
3. Reverse Bias Test: Connect the probes in reverse, placing the black probe (negative lead) at the anode and the red probe (positive lead) at the cathode. When the multimeter is in reverse bias mode, gradually raise the voltage it applies. The multimeter measurement should stay near zero, indicating little current flow, as the voltage gets closer to the Zener diode's breakdown value.
4. Breakdown Voltage Observation: The multimeter reading will leap to a number near the breakdown voltage when the voltage drops to the Zener diode's breakdown voltage, which will cause the current flow to surge dramatically. This shows that the Zener diode is regulating voltage at its breakdown level and operating as expected.

Important Safety Note: Use caution when testing Zener diodes, particularly at higher voltage levels. To guard against excessive current flow and possible damage during testing, it is advised to use a current-limiting resistor in series with the Zener diode.

When to Use TVS Diode?

When safeguarding against brief voltage spikes is crucial, TVS diodes are the recommended option. TVS diodes perform well in the following typical scenarios:

• Automotive Electronics: shielding delicate electronic parts from external sources such as lightning strikes and voltage spikes that come from the alternator, ignition system, and other sources.
• Power Supplies: Preventing voltage spikes that could happen during abrupt on/off cycles or power variations for electronic devices.
• Data Lines: Preventing brief voltage spikes that could taint data impulses by covering them.
• Telecommunication Equipment: Shielding telecom equipment from data cables or phone line voltage surges.
• Consumer Electronics: Protecting TVs, PCs, and other consumer gadgets against voltage transients that might harm internal components is important.

To put it simply, TVS diodes are perfect for protecting electrical circuits in any application where unexpected voltage spikes could damage sensitive components.

Where Zener Diode is Used?

In many circuits where steady voltage regulation is necessary, zener diodes are used. These are a few typical applications:

• Voltage Reference Circuits: Supplying other parts of a circuit with a steady voltage reference point.
• Voltage Regulators: These devices work in tandem with other circuit components to control and sustain a specific voltage level.
• Clipping and Clamping Circuits: This technique limits the maximum voltage swings in a signal path, which is helpful for waveform shaping and noise protection in particular.
• Voltage Regulators in Battery-Powered Devices: Assisting in the maintenance of a steady voltage output from batteries, they guarantee the correct functioning of electronic equipment.

Although it is not their principal usage, Zener diodes can also be used for basic AC to DC conversion in simple rectifier circuits; nonetheless, dedicated rectifier diodes are more efficient in this regard.

Conclusion

Despite their apparent similarities, TVS and Zener diodes have different uses in the field of electronics. As protectors, TVS diodes shield circuits from the fury of voltage transients. Conversely, zener diodes serve as voltage regulators, guaranteeing a constant flow of electricity via a circuit. It is possible to choose and use these two electronic workhorses appropriately in a variety of electronic projects and designs by being aware of the key distinctions between them.

FAQs

What is the purpose of a TVS diode?

TVS diodes are electrical parts that serve as circuit protectors. Its goal is to shield them from potentially harmful abrupt voltage spikes. Static electricity, indirect lightning strikes, or variations in the power source can all cause these surges.

The TVS diode absorbs the extra energy from a voltage surge by kicking in and rerouting the excess current away from the circuit's sensitive components. This shields the most important parts from damage.

To put it briefly, TVS diodes protect electronic equipment from damaging voltage surges by acting as small lightning rods inside the gadget. They ensure the seamless operation of a wide range of gadgets.

How do Zener diodes regulate voltage?

Zener diodes function as tiny electrical pressure regulators. When the voltage rises too high, they open up (breakdown), redirecting surplus current to keep the voltage level constant. Normally, they block current. Consider it as the opening of a valve to release pressure and maintain stability. They work incredibly well in circuits to regulate low-power voltage.

What is the difference between TVS diode and regular diode?

While both regular diodes and TVS diodes regulate current flow, their methods and objectives differ:

• Regular diode: A regular diode permits current to flow in one direction (forward bias) while obstructing it in the other, acting as a one-way highway for electricity (reverse bias). utilized for things like signal routing and rectification, or the conversion of AC to DC.
• TVS diode (Transient Voltage Suppressor): Transient Voltage Suppressor, or TVS diode: Designed to handle sudden surges of energy. It functions as a lightning rod when a voltage spike occurs, directing extra current out of the circuit and safeguarding its constituent parts. gives itself up in dire circumstances.