Control circuit of flyback LED (Light Emitting Diode) driver

Abstract

The invention discloses a control circuit of a flyback LED (Light Emitting Diode) driver. The control circuit of the flyback LED driver comprises a peak valve current sampling unit, a communication time detection unit, a computing compensation unit and a PWM generating unit. According to the control circuit of the flyback LED driver, a primary side feedback control is utilized, system design is greatly simplified, considerable a PCB area and the system size are saved, and system costs are greatly reduced, so that the LED driver can be integrated into an LED lamp conveniently; an optocoupler in the existing control circuit structure is replaced by an auxiliary winding to compensate a network and an reference voltage source; the stability and safety of the system are effectively improved due to the fact that utilization of an off-chip optocoupler and the reference source; and high constant current accuracy is achieved due to the fact that output current accuracy is completely controlled through internal reference voltages.

Description

technical field [0001] The invention belongs to the technical field of LED lighting control, and in particular relates to a control circuit of a flyback LED driver. Background technique [0002] With the continuous development of LED devices, due to its environmental protection, high brightness, long life and mature control methods, the LED lighting market is also expanding. LED drive technology has also been greatly developed. The market's requirements for LED drivers are becoming more and more stringent. High current accuracy and allowing the reduction of peripheral components are the development trends of LED drivers. [0003] The LED itself is a light-emitting diode and a current-controlled device. A very small change in the voltage across the diode can also cause a large change in the current, which will eventually significantly affect the brightness of the LED. Therefore, all drivers must maintain constant current characteristics. Commonly used AC-DC drive structures ...

AI Technical Summary

Problems solved by technology

This feedback method increases the cost and design difficulty. The optical coupling device and the compensation network occupy a large PCB (printed circuit board) area in the board-level system, which increases the volume and cost of the finished product and affects the promotion of LED lighting.

In addition, the accuracy of peripheral devices, including optocoupler T2 and reference voltage source T3, is easily affected by environmental factors, which affects the constant current effect of the controller to a certain extent.

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