In this blog, we will delve into the world of TVS diodes, exploring their functionalities, applications, and how they contribute to the reliability of automotive electronics.

What Are TVS Diodes?

TVS Diodes, or Transient Voltage Suppressor diodes, are a type of component that guards against abrupt voltage spikes in electronic circuits.  Variations in the power supply or static electricity are two possible causes of these surges.  TVS diodes avoid harm by rerouting excess current away from circuit components that are susceptible to damage, much like miniature lightning rods.

What Are TVS Diodes Used For?

TVS diodes are fundamentally used as voltage clamps. They serve as a quick-response switch, safely discharging momentary voltage spikes to the ground and away from delicate electronic components. Below is an outline of their main initiatives:

• Voltage Level Monitoring: TVS diodes continuously keep an eye on the voltage that is present in a circuit.
• Triggering on Overvoltage: The TVS diode quickly transitions to a low-impedance state when a voltage spikes over its preset threshold.
• Shunting Excess Current: The surge current can safely pass through the TVS diode to the ground and avoid damaging electronics thanks to the low-impedance state.
• Reverting to Normal State: The TVS diode returns to its high-impedance state when the voltage surge passes, enabling regular circuit operation to continue.

TVS diodes protect delicate components from damaging voltage spikes by functioning as a regulated dam for excess voltage. This preserves the integrity of the components and guarantees the overall dependability of the vehicle's electronic system.

Why Are TVS Diodes Used?

TVS diodes are the recommended option for transient voltage suppression in automobile electronics because of their many strong advantages:

• Quick Response: As previously indicated, TVS diodes have rapid response times, which enable them to block voltage surges before they can harm delicate components successfully.
• Bidirectional Protection: Suitable for a variety of vehicle electrical circuits, bidirectional TVS diodes protect against voltage transients regardless of polarity.
• Solid-State Reliability: TVS diodes are solid-state devices, which means they don't have any moving components and are typically less prone to failure than more conventional protection techniques like fuses. This leads to the concept of solid-state reliability.
• Cost-Effective: TVS diodes are comparatively cheap parts that provide an affordable way to safeguard priceless electronic parts in an automobile's electrical system.
• Small Size: TVS diodes are perfect for incorporation into automobile electronic circuits with limited space since they are available in small packages.

TVS diodes are a vital tool for automotive engineers because of their many advantages, which guarantee the dependability and durability of electronic systems in contemporary cars.

Video related to How TVS Diodes Work

Are TVS Diodes Bidirectional?

Unidirectional and bidirectional are the two main variants of TVS diodes.

• Unidirectional TVS Diodes: Only one direction of current flow is possible with these diodes. In situations where a single polarity (positive or negative) poses a transient voltage danger, they are usually utilized.
• Bidirectional TVS Diodes: TVS diodes with bidirectional conductivity allow current to flow in both directions. Regardless of polarity, they provide protection against voltage spikes, which makes them appropriate for circuits susceptible to surges coming from either direction.

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

How Fast Are TVS Diodes?

The exceptionally quick response time of TVS diodes is one of its most notable features. They can respond in billionths of a second, or nanoseconds, to spikes in voltage. Transient voltage spikes can be brief yet harmful, thus prompt action is essential to protecting delicate electronic components.

TVS diodes can reroute surge current before it has an opportunity to damage other circuit components because of their extraordinary speed. They are ideal for safeguarding vehicle electronics against erratic voltage transients because of their blazing-fast reaction times.

How TVS Diodes Work?

The electrical characteristics of a unique junction that forms inside TVS diodes between several semiconducting materials are what make the device work. This is a condensed description of how they operate:

1. Doping and Junction Formation: The TVS diode is made by doping various semiconducting materials to produce a p-n junction during the production process. As a gatekeeper, this p-n junction controls the current flow inside the diode. The p-region is positively charged while the n-region is negatively charged in its normal form. As a result, there are relatively few mobile charge carriers in the depletion zone that surrounds the junction, which leads to high impedance and little current flow.
2. Normal Operation: Any voltage applied within the device's designated operating range will encounter this high impedance under normal operating conditions, enabling only a small amount of leakage current to pass through the diode. The TVS diode stays inactive, and the circuit operates as planned.
3. Voltage Spike Exceeds Threshold: The depletion region surrounding the p-n junction narrows suddenly when a voltage transient surpasses the TVS diode's preset threshold rating. This permits an abrupt rise in mobile charge carriers in the area, resulting in a quick change in the diode's characteristics.
4. Low-Impedance State: During this phase, the TVS diode switches from having a high impedance to having a low impedance. In essence, this makes it possible for the surge current to pass through the diode directly.
5. Shunting Excess Current: The surge current is "shunted" or redirected through the TVS diode rather than passing through the circuit's delicate electronic components. As a result, the surplus current can safely leak to the earth.
6. Return to Normal State: The depletion region surrounding the p-n junction widens once again when the voltage transient passes and the voltage drops below the threshold level of the TVS diode. As a result, the circuit operates normally again and the diode returns to its high-impedance state.

TVS diodes function essentially as tiny, voltage-controlled switches. When voltage surges occur, they quickly transition from an active state to a low-impedance state, protecting delicate electronics from damaging currents and keeping them safe.

How to Connect TVS Diodes?

TVS diodes are an effective means of protecting vehicle electronic circuits, but their appropriate connection is essential. As a general rule of thumb:

1. Determine the Vulnerable Elements: Finding the circuit's most susceptible parts, which need to be shielded from voltage transients, is the first step. These are usually parts like integrated circuits, sensors, or LEDs that have a low voltage tolerance.
2. Select Appropriate TVS Diode: Select a TVS diode that has an appropriate voltage rating. The breakdown voltage (BV) of the TVS diode should be sufficiently low to cause a voltage transient, but yet higher than the circuit's typical operating voltage.
3. Placement: The TVS diode should ideally be positioned as close as possible to its guarding component. By doing this, the circuit's lead inductance is reduced, which may have an impact on the diode's response time. In certain situations, designers may choose to position the TVS diode at the circuit board's entry point to offer more comprehensive protection due to space restrictions.
4. Connection Methods: TVS diodes can be connected using one of two main methods:
   • In-Line Linkage: The component that the TVS diode is protecting has one terminal linked to the signal line, while the other terminal is grounded.
   • Line-to-Ground Connection: The component being protected is positioned between the signal line and a specific TVS diode connection point on the circuit board, and both terminals of the diode are connected straight to the ground.

The particular application and circuit architecture determine the best connection technique. For correct installation, it is imperative to refer to the datasheet of the selected TVS diode and adhere to the manufacturer's instructions.

Where Should TVS Diodes Be Placed?

The efficiency of TVS diodes in an automotive electrical circuit depends on where they are placed. The following are some crucial factors to take into account while placing TVS diodes in vehicle electronics:

• Component Protection: Placing the TVS diode as close to the component it is protecting is the main objective. By doing this, the circuit's lead inductance is reduced, which might momentarily slow down the diode's response to a voltage spike. The power and ground pins of the TVS diode should ideally be connected directly to the same component.
• Space Restrictions: It may not always be possible to place the TVS diode exactly next to every protected component on a circuit board because of space restrictions. In these kinds of situations, a more calculated strategy is needed. Here are two typical approaches:
  • Group Protection: A collection of adjacent components that share a common power or ground line can be shielded by a single TVS diode. When the components are close to one another and have comparable voltage ratings, this method works well.
  • Bulk Protection: TVS diodes can be installed at a circuit board's entry points, like the connector for the power input or certain signal lines that enter the board. Although it gives more comprehensive protection for the circuit as a whole, this could not be as effective as protection at the component level.
• Signal Integrity: Selecting TVS diodes with low capacitance is essential for safeguarding delicate signal lines. In high-frequency circuits, excessive capacitance can cause unintended signal distortion or attenuation.
• Thermal Management: TVS diodes can produce heat when operating, particularly when managing high transient currents. It's critical to take into account the TVS diode's capacity for heat dissipation and, if required, make sure that the appropriate heat sinking is in place. This is especially crucial for instances where the TVS diode may come into contact with the hot interior temperatures of the vehicle.

Your automobile electronic circuits will be best protected if you adhere to these installation rules and review the manufacturer's recommendations for the particular TVS diode model.

Conclusion

TVS diodes are essential for protecting the sensitive electronic parts of contemporary cars. Because of their outstanding speed, small size, and affordability, they are the best option for reducing the risks related to temporary voltage spikes. TVS diodes contribute to the overall longevity and dependability of automobile electrical systems by efficiently suppressing these surges, guaranteeing a safe and comfortable driving experience.

FAQs

What does a TVS diode do?

Electrical circuits are shielded against transient voltage spikes by transient voltage suppression diodes (TVS diodes), which can be brought on by electrostatic discharge or lightning. Crucial elements consist of:

• Clamping Voltage: During a spike, it lowers the voltage to a safe level.
• Quick Response: Responds to transients in a matter of nanoseconds on average.
• Types: Available in unidirectional (for one polarity) and bidirectional (for both polarities).
• Energy Absorption: This process takes in and releases the energy associated with voltage spikes.
• Low Leakage: Very little disruption to regular circuit functioning.

What is the difference between the TVS diode and Zener diode?

While they both manage voltage, TVS and Zener diodes have distinct purposes:

• TVS diode: The TVS diode is a circuit protector. prevents abrupt voltage spikes, such as power or static surges, to safeguard fragile components. behaves as a lightning rod and will give itself up if necessary.
• Zener diode: Controller of voltage. keeps the voltage constant by permitting current to flow when the voltage rises too high. Consider it similar to how a faucet modifies the flow of water.

Although both are directed, Zeners manage constant lower currents, whereas TVS diodes are for brief spikes in high currents. For surge protection, TVS diodes can be found in everything from cars to phones, while Zeners are used in voltage reference circuits.

Where should TVS diodes be placed?

Reducing the distance between TVS diodes and possible points of entry for undesired voltage spikes is the key to their optimal placement. The following are some essential ideas:

• Close to the Connector: Installing TVS diodes immediately adjacent to connectors is a smart idea because these are frequently the points of entry for voltage spikes into a circuit.
• Direct Path to Ground: There is less inductance to obstruct the TVS diode's reaction to a surge the shorter the trace is between the connector and the diode.
• Direct Path to Ground: For best results, the ground terminal of the TVS diode and the ground plane of the circuit should be connected as directly as feasible.
• Separate Signal and Power Lines: Steer clear of connecting any signal trace to any line that could potentially carry a surge in parallel. Install the TVS diodes directly on each line.

Can a single TVS diode protect multiple circuits?

Sure, in some circumstances. A single TVS diode can be used to safeguard a group of adjacent components sharing a common power or ground connection and having comparable voltage ratings. Nonetheless, it is advised to use individual component-level protection with TVS diodes positioned immediately adjacent to each component for the best possible protection.