A kind of LED switching power supply and its control method

Abstract

The invention discloses an LED switch power supply and a control method thereof. The power supply comprises a controllable silicon dimmer, a rectification bridge, a PFC power factor correction circuit, a flyback voltage conversion circuit and an output interface. The first input end of the rectification bridge is connected with one end of the controlled silicon dimmer. The other end of the controllable silicon dimmer is connected with one end of an alternating current power supply. The second input end of the rectification bridge is connected with the other end of the alternating current power supply. The grounded end of the rectification bridge is grounded. The output end of the rectification bridge, the PFC power factor correction circuit, the flyback voltage conversion circuit and the output interface are connected in sequence. According to the method, a flyback control chip is used to detect the conduction angle of the controllable silicon dimmer, so that the duty ratio of the output voltage of the output interface is adjusted, and the purpose of dimming is realized. According to the invention, voltage corresponding to the duty ratio is output according to different conduction angles of the controllable silicon dimmer, so that a dimming function is realized without the processing of a post stage circuit; the dimming accuracy is high; and the system cost is reduced.

Description

technical field [0001] The invention relates to the technical field of power supplies, in particular to an LED switching power supply and a control method thereof. Background technique [0002] Current switching power supplies such as Figure 4 As shown, the output is a constant voltage or current source, a switch is connected in series with the load, and the post-stage circuit is required to control the duty cycle of the switch, so as to realize the change of the average current of the load, thereby realizing dimming, the added switch and the post-stage circuit Increased system cost. [0003] Chinese Patent Publication No. 2781641, published on May 17, 2006, the name of the utility model is a switching power supply. The application discloses a switching power supply, which includes a power switching tube, a pulse width modulation circuit, an energy storage filter capacitor and a transformer. , wherein the output end of the pulse width modulation circuit is connected to the...

AI Technical Summary

Problems solved by technology

Its disadvantage is that the output of the switching power supply is a constant voltage, which needs to be processed by the post-stage circuit to realize the LED dimming function, which increases the system cost

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