Improvement of ESD Damage Test Board for CMC for Automotive Ethernet

Abstract

IEC 62228-5 requires an electrostatic discharge (ESD) damage test of common-mode chokes (CMCs) used in the electromagnetic compatibility evaluation of automotive Ethernet transceiver integrated circuits (ICs). However, with the recommended ESD damage test board in IEC 62228-5, mounting and remounting of 0- $\Omega $ resistors in the S-parameter measurement route (microstrip lines) are needed, which may cause uncertainty in the S-parameter measurement results. In this letter, we propose and validate an improved ESD damage test board which ensures both S-parameter measurement and ESD application. The proposed test board removed the 0- $\Omega $ resistors and the vias of discharge points (DPs) from the microstrip lines between the SMA connectors for connection to a vector network analyzer and the CMC. As a result, the proposed test board was able to reduce the effects caused by the mismatched parts on the microstrip lines. For validation, ESD current waveforms were measured and compared for the original and proposed test boards, with concern for discharge at the SMA connectors. As a result, the proposed test board shows almost the same discharge current waveform as the original test board. In addition, based on the relationship between the applied ESD voltage and the first peak of the discharge current, determining whether a discharge occurs at the SMA connector on the DP side was examined. The result confirmed that the first-order proportional relationship between the ESD voltage and the first discharge peak current was maintained for the proposed test board, which suggests the validity of the proposed test board for the ESD damage test.