Led pwm constant current driving circuit and mixing three primary colors of light led drive circuit

The present invention provides a constant current LED driver circuit and the PWM three-color LED light mixing drive circuit. The LED constant current PWM drive circuit comprising: a triac switching circuit is connected to the AC power supply, a sinusoidal AC signal for converting AC power supplied chopped sinusoidal waveform signal; PWM waveform signal generating circuit of the three-terminal bidirectional switching circuit is connected to, for generating a waveform signal using the sinusoidal PWM chopping signal waveform; constant current LED drive circuit, the waveform of the PWM signal generating circuit is connected with the PWM waveform signal for controlling the LED light source turned on and off, in order to achieve constant current PWM LED driving. In the present invention, the triac drive circuit is directly load is a resistive load, a capacitive load is not, therefore this solution ensures a high power factor, without affecting the quality of the entire grid.