In addition to the shock caused by hot insertion, other causes of EOS at the input end of the power supply IC may cause the input end of the power supply IC to be attacked by EOS: the short circuit test of the USB output end causes damage to the input end of the USB switch. A typical USB switch In the application circuit diagram, there is a 1µF decoupling capacitor placed close to the input of the IC, and a copper foil path of about 10cm in front of the capacitor connects it to the 5V mains supply.
USB ports need to be short-circuit tested. This test is simulated by a switch, and the IC needs to quickly turn off its MOSFET switch after detecting a short circuit. As can be seen from the example, the action of the MOSFET switch turn-off is delayed, so there will be a short-term high current flowing through the IC before the turn-off will occur. Due to the inductance of the input line, this inductance and the input decoupling capacitor C2 will resonate together, so a high voltage pulse can be seen at the input on the oscilloscope, which is likely to exceed the maximum voltage capability of the IC and destroy it. To address such reliability concerns, similar measures for hot-plug risk prevention can be considered.