How can a poor grounding of the PAC (Power Actuator) cause the system to crash?

Poor grounding of the intelligent controller PAC can introduce common-mode noise, cause potential fluctuations, and lead to system reset, data errors, or even crashes. Specific mechanisms include: excessively high grounding impedance causing a large voltage drop in transient currents (such as EFT and surges), coupling into signal lines; ground loops forming antennas, receiving spatial radiated interference; and poor high-frequency grounding resulting in incomplete digital signal return paths, causing ringing and false triggering. A typical example is a loose chassis grounding screw (contact resistance >100mΩ), causing CPU reset due to sudden ground potential changes during power-on and power-off.

Solutions include: checking and tightening all grounding connections to ensure contact resistance <10mΩ; adding common-mode filtering (such as CMZ3225A-510T) and TVS protection (such as SMBJ6.5CA) to power and signal interfaces; and optimizing the PCB ground plane to avoid splitting. After rectification, the PAC's crash rate in the IEC61000-4-4 EFT test (4kV) decreased from 30% to 0%, and the system MTBF increased to over 100,000 hours.