Xinhaoyang

TVS diodes are widely used to protect circuits transient voltage damage, and selecting the correct TVS diode is crucial to ensuring the stability and safety of the equipment.

1. Reverse Standoff Voltage (VR)

The reverse turn off voltage is the highest voltage that a TVS diode can withstand in a non-conductive state. When selecting, the VR should be slightly higher than the normal operating voltage of the protected circuit to ensure that the TVS diode will not conduct under normal operating conditions. For example, for a circuit with a working voltage of 12V, it is recommended to choose a TVS diode with VR between 13V and 15V.

2. Breakdown Voltage (VBR)

The breakdown voltage refers to the voltage value at which the TVS diode begins to conduct and provide protection. This parameter is usually represented by the voltage measured at a current value (such as 1mA). The breakdown voltage should be slightly higher than the reverse turn off voltage and below the maximum operating voltage of the circuit. For example, for a circuit with a maximum operating voltage of 14V, the breakdown voltage should be between 15V and 17V.

3. Clamping Voltage (VC)

Clamping voltage refers to the voltage value at which a TVS diode limits the voltage within a safe range during transient events. When the transient voltage exceeds the breakdown voltage, the TVS diode will conduct and clamp the voltage below VC. The lower the clamping voltage, the better the protection effect on the circuit. When selecting, it should be ensured that the clamping voltage is lower than the maximum withstand voltage of the protected device.

4. Peak Pulse Current (IPP)

The peak pulse current is the maximum current value that a TVS diode can withstand within a specified pulse duration. This parameter reflects the current handling capability of TVS diodes under transient events. When choosing IPP, it should be ensured that it is greater than the peak transient current that may occur. For example, for a circuit that may generate 100A pulse current, the IPP of the TVS diode should not be lower than 100A.

5. Dynamic Resistance (RD)

Dynamic resistance refers to the resistance value of a TVS diode when it conducts after breakdown. The lower the dynamic resistance, the better the clamping effect of the TVS diode. Therefore, choosing TVS diodes with lower dynamic resistance can help improve the protection effect of the circuit.

6. Junction Capacity (CJ)

The junction capacitance is the capacitance value of a TVS diode when reverse biased. The impact of junction capacitance is particularly significant for high-speed data communication lines or RF circuits. High junction capacitance can affect signal integrity and transmission speed, so TVS diodes with lower junction capacitance should be selected in these applications. For example, in high-speed communication lines, it is recommended to choose TVS diodes with junction capacitance in the range of several picofarads (pF).

7. Packaging form and size

The packaging form and size of TVS diodes are also factors that cannot be ignored in the selection process. Different application scenarios have different requirements for packaging form and size. For example, in portable devices with limited space, TVS diodes packaged in SMD (Surface Mount Device) are more suitable. In high-power devices, choosing TVS diodes with larger packaging sizes can help improve heat dissipation performance and current handling capabilities.

8. Operating temperature range

The operating temperature range of TVS diodes determines their applicability under different environmental conditions. For equipment that needs to operate under extreme temperature conditions, it is important to choose TVS diodes with a wide temperature range (such as -55 ° C to+150 ° C).

9. Reliability and lifespan

Reliability and lifespan are factors that cannot be ignored in the selection process. High quality TVS diodes should have good reliability and long lifespan to ensure their stability and effectiveness during long-term use. By reviewing the reliability testing data and certifications provided by the manufacturer, it can help select more reliable TVS diodes.

The selection of TVS diodes requires comprehensive consideration of multiple parameters such as reverse turn off voltage, breakdown voltage, clamping voltage, peak pulse current, dynamic resistance, junction capacitance, packaging form, operating temperature range, reliability, and lifespan. Only by comprehensively understanding and selecting these parameters reasonably can TVS diodes provide effective circuit protection in practical applications.