Tool/software:
Dear Expert
100w Module
Exception description:
Using LM5025CMTCX as the control chip and CS1 pin for short circuit protection, the CS1 voltage reaches the protection point of 0.5V during a short circuit, and the chip enters cycle by cycle current limitation. At this time, the COMP voltage rises to saturation (5V), and CS2 reaches 0.5V through a voltage divider resistor, and the chip further enters hiccup protection; At the beginning, the chip had a hiccup cycle of over 60 ms, but as time passed, the hiccup interval became shorter and shorter, reaching only about 3 ms later on, and the hiccup was no longer regular; At this point, as the input power of the primary side increases, the temperature of the primary side MOS transistor also rises, ultimately leading to thermal damage of the MOS transistor. Our SS pin capacitor is 0.047uF, and when the CS2 pin voltage reaches 0.5V, the charging current for the SS pin capacitor is 1uA. The calculated time for charging the SS pin with 1uA current to 1V is 47ms. Therefore, the theoretical hiccup period is ≥ 47ms, and 3ms does not match the theoretical calculation,
