How to troubleshoot functional abnormalities after ESD testing of an edge computing box?

If an edge computing box experiences a system crash, reset, or communication anomaly after ESD testing, the following four steps should be followed for troubleshooting: First, visually inspect the ESD protection devices. Check the ESD diodes or TVS for cracks or carbonization marks. For example, if the ESD5V0D8B uses an SOD882 package and is burned out due to overcurrent, use a multimeter to measure the forward and reverse voltage drops of the I/O to ground. A normal value is approximately 0.6V. A short circuit indicates breakdown. Second, use an oscilloscope to measure the power rail voltage. During the instant of discharge, the residual clamping voltage of the TVS (e.g., 5.0SMDJ33CA) should be lower than the chip's withstand voltage. If the voltage drop is too low, the TVS voltage needs to be increased. Check the interface filtering circuit again, such as the S power or pre-amplifier bead. For example, the HDMI interface uses ESDDLLC5V0D8BH. Its naming is ESDDLLC ultra-low capacitance 5V0 shutdown voltage D8BH package DFN1006-2L. The suffix H indicates high reliability. If this device is damaged, it will cause signal distortion. Finally, verify the PCB grounding impedance. The ESD current discharge path must be short and thick and directly connected to the ground plane. Grounding with low impedance can solve 90% of functional abnormality cases. E-Tech Electronics provides ESD device failure analysis services to assist in locating the root cause.