Secondary side synchronous rectification circuit with thermal protection function, and electronic equipment

Abstract

The invention discloses a secondary side synchronous rectification circuit with a thermal protection function, and electronic equipment. According to the secondary side synchronous rectification circuit, a temperature detection unit is additionally arranged in the secondary side synchronous rectification circuit to monitor the temperature of a power tube, so when the temperature of the secondary side synchronous rectification circuit rises to a threshold value of thermal protection temperature detection, the temperature detection unit detects the temperature of the circuit and outputs corresponding feedback quantities to an optocoupler end according to detected different temperature quantities, and the optocoupler outputs corresponding feedback quantities to a primary side control module according to the received feedback quantities; and thus, the primary side control module is controlled to control primary side input power, the effect of reducing the temperature of the secondary side synchronous rectification circuit is achieved by reducing the input power, and in a normal working state, electric energy consumed by the load is detected and controlled through a constant-voltage constant-current unit, so the secondary side synchronous rectification circuit works in a stable state. The secondary side synchronous rectification circuit can work at a constant temperature, and the thermal protection of the secondary side synchronous rectification circuit is also realized.

Description

technical field [0001] The invention relates to the field of power electronic conversion, in particular to a secondary side synchronous rectification circuit with thermal protection and electronic equipment. Background technique [0002] With the development of modern electronic technology, the operating voltage of the circuit is getting lower and the current is getting higher and higher, so the overall power loss of the circuit has become an important consideration in circuit design. Traditional secondary rectification circuits usually use Schottky rectifier diodes, but as the operating voltage of the circuit becomes lower and lower, the efficiency of the circuit also decreases. Synchronous rectification (Synchronous Rectification, SR) technology is widely used in low-voltage, high-current power modules due to its advantages of low power consumption. [0003] Although the synchronous rectification technology adopts the method of replacing the Schottky rectifier diode with ...

AI Technical Summary

Problems solved by technology

[0003] Although the synchronous rectification technology adopts the method of replacing the Schottky rectifier diode with the power tube to greatly improve the efficiency of the circuit, but the power device will increase the heat due to the increase of the output power. When it exceeds 165 degrees, the synchronous rectification control circuit and There will be thermal breakdown in the power tube, which will damage the chip. In most existing secondary side synchronous rectification circuits, the thermal protection method adopted is to turn off the power NMOS (N-Metal-Oxide-Semiconductor) tube of the synchronous rectification, but in fact After turning off the NMOS, because the parasitic diode of the power NMOS is turned on, the circuit is still in the conduction state, and the conduction voltage drop is close to 1V, and the conduction voltage drop is larger, so it will cause the instability of the working system and cause oscillation, and there is a huge The hidden danger of abnormal thermal protection

Images