Tool/software:
Hello：
1. In the 2A module, UCD3138 is damaged at pin 22, which is a short circuit to ground. This pin is used for ON/OFF control. It has a 10K resistor pulled down internally and a 10nF capacitor connected in parallel. An external 30K resistor is pulled up to 12.2V, forming a voltage divider between the 30K and 10K resistors. The factory uses a relay to control the opening and closing of the voltage divider resistor 10K to achieve ON/OFF function; The module of 2A has broken this chip.
2. In the 2C module, the damaged UCD3138 is the power supply pin 27, which is also short circuited to ground. This is powered by TI's LP2985A-33DBVR, and the damaged operation was to perform a startup test on the module. Therefore, this 3.3V short circuited during startup. After replacing the chip, the 3.3V startup test showed a monotonic increase without any spikes. The 2C module has three broken chips, all with the same issue.
Please help to see what are the common causes of this type of short circuit problem. Thank you!!!
