SHORT-CIRCUIT PROTECTION CIRCUIT FOR VOLTAGE SAMPLING RESISTOR OF PRIMARY SIDE CONVERTER

摘要

Disclosed is a short-circuit protection circuit for a voltage sampling resistor of a primary side converter, comprising a high voltage power transistor, a high voltage starting resistor, a first voltage dividing resistor of a port VDD, a second voltage dividing resistor of the port VDD, an NMOS transistor, a diode, a first comparator, a second comparator, a third comparator, a time delay circuit, a filter, a first logic circuit, a second logic circuit, a current supply, a first AND gate and a first inverter. The chip of the present disclosure is capable of correctly and effectively detecting whether the sampling resistor is shorted or not before the chip works normally, thereby avoiding the risk of damaging the chip by large current from the voltage feedback port FB due to turn-on of the switching transistor when the upper voltage sampling resistor is shorted, and greatly reducing the input power.

主权项

1. A short-circuit protection circuit for a voltage sampling resistor of a primary side converter, comprising:
a high voltage power transistor electrically connected with a high voltage starting port, a power supply port, a high voltage starting resistor, a diode, and an NMOS transistor; a first voltage dividing resistor of the power supply port; a second voltage dividing resistor of the power supply port; a first comparator electrically connected with the first voltage dividing resistor, the second voltage dividing resistor, a first logic circuit, a second logic circuit, and a second comparator; the second comparator electrically connected with the first logic circuit, the second logic circuit, and a time delay circuit; a third comparator electrically connected with a current supply, a voltage feedback port, and a first inverter; the second logic circuit electrically connected with the time delay circuit and a first AND gate; the first logic circuit electrically connected with the NMOS transistor and the first AND gate; the first inverter electrically connected with a filter; and the filter electrically connected with the time delay circuit and the first AND gate.