Content:

• Introduction
• General Characteristics of TVS Diodes
• Functions of TVS Diodes
• Basic TVS Diode Topologies

Introduction

Electrostatic discharge (ESD) refers to the time when static electricity stops being static and actually zaps. For people, this is painful and maybe amusing to friends but generally not a problem. With electronics, an ESD event can completely destroy a piece of electronics or, perhaps worse in some situations, cause intermittent, difficult-to-trace faults. These events can be controlled in the prototyping and production phases, but once a product is released into the wild, it needs to be robust enough to withstand anything your customers throw at it. While nothing will make a board completely impervious to ESD, there are ways to make it much less susceptible, using both well-thought-out board design and additional protection devices.

Transient Voltage Suppression TVS diodes are essential components in electronic circuits, designed to protect sensitive devices from voltage spikes and transient surges. These diodes respond rapidly to overvoltage conditions, clamping excessive voltage and diverting harmful currents away from critical components.

In this blog, we’ll explore the general characteristics, functions, and basic topologies of TVS diodes to help you understand their role in circuit protection.

1. General Characteristics of TVS Diodes

TVS diodes are specialized semiconductor devices with unique properties that make them ideal for transient suppression:

1.1 Fast Response Time

• TVS diodes react almost instantaneously (in picoseconds) to transient events, far faster than other protection devices like varistors or gas discharge tubes.

1.2 High Surge Current Handling

• They can handle large surge currents (from a few amps to several hundred amps) for short durations, making them suitable for high-energy transients.

1.3 Low Clamping Voltage

• When activated, TVS diodes clamp the voltage to a safe level (V₍C₎ – Clamping Voltage) below the breakdown threshold of protected components.

1.4 Bidirectional vs. Unidirectional Operation

• Unidirectional TVS diodes protect against positive voltage spikes (used in DC circuits).

• Bidirectional TVS diodes suppress both positive and negative transients (used in AC circuits).

1.5 Low Leakage Current

• In normal operation, TVS diodes exhibit minimal leakage current, ensuring they don’t interfere with circuit performance.

2. Functions of TVS Diodes

TVS diodes serve two primary functions in electronic circuits:

2.1 Voltage Clamping

• When a transient voltage exceeds the diode’s breakdown voltage (V₍BR₎), it enters avalanche mode, clamping the voltage to a safe level (V₍C₎).

2.2 Current Diversion

• The diode shunts excess current to ground, preventing it from reaching sensitive components like ICs, microcontrollers, or communication lines.

Common Applications:

• ESD Protection (USB, HDMI, Ethernet ports)

• Lightning & Surge Protection (Power lines, telecom circuits)

• Automotive Electronics (Load dump protection in 12V/24V systems)

• Industrial Equipment (Protection against inductive switching transients)

3. Basic TVS Diode Topologies

TVS diodes can be implemented in different configurations depending on the application:

3.1 Single TVS Diode Protection

• A single TVS diode is placed in parallel with the protected circuit.

• Suitable for low-voltage DC lines (e.g., USB data lines).

3.2 TVS Diode + Series Resistor (For Current Limiting)

• A resistor limits the current during a transient event, reducing stress on the TVS diode.

• Used in signal lines where resistance doesn’t affect performance.

3.3 Dual TVS Diodes for Differential Line Protection

• Used in high-speed data lines (e.g., RS-485, CAN bus) to protect against differential transients.

• Two diodes clamp positive and negative transients.

3.4 TVS Array (Multi-Line Protection)

• Multiple TVS diodes integrated into a single package for protecting several I/O lines (e.g., HDMI, Ethernet).

• Reduces PCB space and ensures uniform protection.

Conclusion

TVS diodes are critical for safeguarding electronics from transient voltage events. Their fast response, high surge handling, and flexible topologies make them ideal for ESD, surge, and overvoltage protection in various applications.

By selecting the right TVS diode type (uni/bi-directional) and topology, engineers can ensure robust circuit protection while maintaining signal integrity.

Would you like recommendations for specific TVS diode models based on your application? Let us know in the comments!