Overpower compensating method and device for wide voltage-input flyback power supply

Abstract

The invention relates to an overpower compensating method and an overpower compensating method for the wide voltage-input flyback power supply. The device comprises a flyback transformer of a flyback power supply, an OPP overpower compensating circuit and a PUM control IC serving as the flyback power supply. The method and the device are characterized in that: a winding is arranged on a primary side of the transformer, one end of the winding used as an unlike end is connected with a primary side reference ground, while the other end used as a like end transmits the voltage, which is generated by coupling, to an OPP overpower protection and detection functional end CS of the PUM control IC serving as the flyback power supply by the OPP overpower compensating circuit to perform the OPP overpower compensation. The method and the device can make an overpower protection point of a wide power supply (which inputs a 90-264 Vrms alternating current) closer and the OPP overpower compensating circuit does not work at a light load, which means the OPP compensating power has no power loss when a light load is output, so the method and the device can be applied to a flyback type wide-range power supply with low requirements on standby power consumption, the use is convenient and safe and the damages of parts, such as a switch MON tube, caused by output overload or short circuit are also reduced simultaneously.

Description

technical field [0001] The invention relates to a method and device for over-power compensation of a wide-voltage input flyback power supply. Since the compensation circuit is turned off at light load and does not consume power, it can be applied to liquid crystal display products that require very low standby power. Excited power supply. Background technique [0002] At present, the power supply of most LCD products usually adopts a flyback topology, and the input voltage is usually designed with a wide power supply of 90Vrms-264Vrms. In order to ensure that the power supply parts are not damaged or cause safety problems when the output is overloaded or short-circuited, the power supply The board is usually designed with an over-power protection (OPP) function, and most current flyback power supply over-power protection is as follows: figure 1 and image 3 two kinds. [0003] figure 1 The over-power protection circuit is composed of Rs, R901, and C901. By detecting whet...

AI Technical Summary

Problems solved by technology

The R912 resistance value is greater than 2M, and the problem of insufficient OPP overpower compensation occurs, that is, when the power input is between 90Vrms-264Vrms, the power output overpower protection point begins to have a large difference

Images