Isolation led drive circuit

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.