Other Parts Discussed in Thread: TPS54360
Fault analysis: all belong to the same phenomenon, that is, CAN chip burn-out and core board DDR burn-out. Based on our previous experience in research and development, the analysis is that the power supply chip TPS54360 on the backplane has an organic output voltage higher than 5V under hot-swappable conditions, thus burning down the CAN chip. Core board and other devices (recommended for your company or using hot-swappable power chips). First, the following figure is a recommendation for TI:
As a result of your design, the EN pin of the power supply chip does not have a pull-down resistance. During startup, when the input voltage rises to 3.3v (Zener diode rating), the Ven=Vin. The voltage of the power chip EN is 1.2V, which means that the power chip will be started when the Vin > 1.2V, which is a serious deviation from the design state of the power chip (the default state is Vin > 4.3V, the chip will only start. And this value is only allowed to be raised). If the plug and socket contact is bad, the input voltage Vin fluctuates frequently, the power chip will not start normally (under the condition of less than 4.3V), and the logic control circuit status in the chip will not reset normally, and if the plug-and-socket contact is not good, the input voltage will fluctuate frequently. It is possible to cause the built-in MOS tube to be switched on abnormally, and the output of the power circuit will be significantly higher than 5V or even equal to the input voltage of Vin. The current of the EN foot is about 1.2uA, so without the pull-down, the Ven is almost equal to Vin.
