Isolated led drive circuit

Abstract

The invention discloses an isolation LED drive circuit, and belongs to the technical field of LED drive. The isolation LED drive circuit comprises a fly-wheel diode, a transformer, an auxiliary winding, a power tube, a sense resistor and a constant current controller. An LED is connected with a primary side winding of the transformer in series, the fly-wheel diode is connected with the two ends of a series branch formed by the LED and the primary side winding of the transformer in parallel in the reverse direction, the input end of the power tube is connected with the primary side winding of the transformer, the output end of the power tube is grounded through the sensor resistor, and the auxiliary winding is connected in a secondary side loop of the transformer in series. The constant current controller comprises a zero crossing detector, a bottom detector, a peak detector, a scaling factor amplifier, an on-off control unit, an integral unit, a transconductance amplifier, a comparator and an RS trigger. A duty ratio mapping technology is adopted for the isolation LED drive circuit, and constant current precision of the circuit under different loads is guaranteed.

Description

technical field [0001] The invention discloses an isolated LED driving circuit, which belongs to the technical field of LED driving. Background technique [0002] In the field of lighting, light-emitting diode (LED: Light Emitting Diode) lighting has become the mainstream today, and LED-related driver chips have also become a hot spot in the field of integrated circuit design, but the design level of driver circuits is uneven. The flow accuracy can only be ±5%, the efficiency is generally low, and the efficiency is generally between 70% and 90%. The real high-precision and high-efficiency drive technology is mostly in the hands of several large foreign companies, so domestic LED In the driving field, it is difficult to find a driving circuit with an output power of 15-20W, an efficiency higher than 90%, and a constant current accuracy of ±2%. The present invention is an LED constant current control module designed to address the above shortcomings. [0003] LED drive method...

AI Technical Summary

Problems solved by technology

At present, most of the ways to achieve constant current adopt the popular structure with a fixed ratio between degaussing time and cycle, but this structure is difficult to achieve full voltage, high efficiency, the maximum duty cycle is less than 50%, and the power is difficult to break through 10W

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