How to troubleshoot a data center switch RS test crash?

Data center switch RS radiation immunity tests often fail due to insufficient sensitivity of the reset circuit or PCB resonance. Troubleshooting methods:

1. Scan the 80MHz-1GHz band in 5MHz increments to locate sensitive frequencies;

2. Use a near-field probe to scan the PCB for high field strength areas;

3. Add common-mode filtering to the suspected pin (reset interrupt clock).

Corrective measures: Connect a TVS (such as the ESD3V3D3B from Etymex, VRWM=3.3V, junction capacitance 12pF) in parallel with the reset chip power supply to ground to clamp transients; ground the crystal oscillator casing; add an absorption patch to the PCB resonant area.

A test showed that a certain model experienced a 20V/m crash at 780MHz, but passed the 30V/m test after connecting a PBZ1005B-102Z0T ferrite bead in series with the reset line.