When selecting TVS (Transient Voltage Suppression) diodes, the following voltage and current parameters are your main concerns:
1. Maximum reverse working voltage (V_RWM): This is the maximum reverse voltage that the TVS can withstand under normal operating conditions. When specifying this value, make sure that V_RWM is greater than the normal operating voltage of the circuit to avoid false triggering during normal operation.
2. Breakdown voltage (V_BR): When reverse voltage across the diode reaches its breakdown voltage, the TVS begins to conduct and limit the voltage. The selected TVS should ensure that its breakdown voltage is higher than the maximum normal operating voltage of the circuit, but lower than the withstand voltage of the component being protected.
3. Maximum peak pulse current (I_PP): This is the maximum transient pulse current that the TVS can withstand. When specifying this value, consider the possible surge current your circuit could experience and ensure that the TVS can safely handle these transient events.
4. Maximum clamping voltage (V_C): The highest voltage that the TVS can limit at the maximum peak pulse current. This value must be lower than the maximum withstand voltage of the protected component to ensure that it is not damaged.
5. Reverse leakage current (I_R): At the maximum reverse operating voltage, the reverse leakage current of the TVS should be kept within an acceptable range. Excessive leakage current may affect the normal operation of the circuit.
6. Junction capacitance (C_j): The junction capacitance of the TVS affects its response speed and signal transmission quality. For high-frequency signal applications, it is crucial to choose a TVS with low junction capacitance.
Summary:
When selecting a TVS, the above voltage and current parameters need to be considered comprehensively to ensure its effective protection performance in the circuit and avoid affecting normal operation.