LED dimming driver and LED light source system

The utility model relates to an LED dimming driver and an LED light source system. The LED dimming driver comprises an EMI filter circuit, a rectifier circuit, a PFC circuit, a high-frequency DC\DC voltage reduction isolation converting circuit, a PWM control circuit, an output voltage feedback control circuit, an initial voltage regulating part, a D/A conversion circuit, an MCU chip and an isolation optocoupler A and B, wherein the EMI filter circuit, the rectifier circuit, the PFC circuit and the high-frequency DC\DC voltage reduction isolation converting circuit are connected successively, an input terminal of the PWM control circuit is connected with an output terminal of the isolation optocoupler A, an output terminal of the PWM control circuit is connected with a control terminal of the high-frequency DC\DC voltage reduction isolation converting circuit, the initial voltage regulating part is connected with an input terminal of the MCU chip, an output terminal of the MCU chip is connected with the output voltage feedback control circuit through the D/A conversion circuit and then connected with an input terminal of the isolation optocoupler A, the input terminal of the MCU chip is connected with the isolation optocoupler B, and an input terminal of the isolation optocoupler B is connected with a switch adjusting interface. The LED light source system comprises the LED dimming driver and a plurality of LED lamp sets connected in parallel at an output terminal of the LED dimming driver, and each LED lamp set comprises current limiting elements and a plurality of LED lamps, and the current limiting elements and the LED lamps are connected in series. The LED dimming driver and the LED light source system satisfy continuous dimming of the fixed-connection and non-fixed-connection lamps and are simple and convenient in construction.