How much does poor grounding of a data center switch affect surge protection?

Poor grounding in data center switches can cause surge currents to fail to dissipate through a low-impedance path and instead enter the motherboard along signal lines. TVS (Transient Voltage Suppressor) circuits (TVS) with excessively large grounding loop inductance can generate residual voltage spikes (L·di/dt) that can increase by 30%–50% in actual measurements. For example, with an 8/20μs surge of 1kA, a grounding inductance of 10nH generates a residual voltage of 200V, far exceeding the chip's tolerance threshold. The rectification solution employs multi-point grounding technology, placing the TVS grounding vias directly onto the chassis ground plane. The number of vias is ≥4, with a parallel equivalent inductance <2nH. A 7D391K varistor (varistor voltage 390V) is connected in parallel at the power port, along with a CMZ7060A-701T common-mode inductor (700Ω@100MHz) to form a low-impedance discharge path. After grounding optimization, the measured surge residual voltage decreased from 78V to 34V, passing the IEC61000-4-5 4kV test.