Q: How to implement ESD protection on PCB input/output connectors?
Answer
Place ESD protection as close to the connector as possible – ideally within 5 mm. Select TVS diodes with clamping voltage below the protected IC maximum rating. For USB: USBLC6-2SC6 (ST) ESD851 or RCLAMP0524P. For RS-485/232: RS485/232-specific TVS arrays with +-15 kV IEC 61000-4-2 contact discharge. For GPIO/sensor inputs: unidirectional TVS (or bidirectional for AC signals). Series resistance (33-330 Ohm) adds current limiting between connector and IC. For high-speed USB/HDMI use low-capacitance (<1 pF) TVS diodes to avoid signal integrity degradation. Follow IEC 61000-4-2 for 150 pF/330 Ohm discharge network.
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