How to select a TVS diode for a motion controller with an MC interface

When selecting TVS diodes for the interfaces of a motion controller (MC), the protection objectives must be clearly defined. First, determine the normal operating voltage and signal type of the protected circuit. The TVS's reverse operating voltage (VRWM) should be slightly higher than the circuit's maximum normal operating voltage. The clamping voltage (VC) must be lower than the maximum withstand voltage of the protected device. The peak pulse current (IPP) should be estimated based on the potential transient energy. For data lines, low-capacitance models, such as the ESDLC series, must be selected to maintain signal integrity. For power lines, higher-power TVS diodes, such as the SMBJ and SMCJ series, can be selected. Bidirectional TVS diodes are used for AC circuits or circuits that may withstand positive and negative transients. Package size and mounting method should also be considered during selection. After selection, it is best to test in an actual circuit to verify its actual clamping effect and reliability under ESD, EFT, or surge conditions. TVS diodes are delicate protection devices and must be used in conjunction with upstream coarse protection.