The invention provides a primary side
constant current controlled quasi single-stage high
power factor circuit and device. The circuit comprises a
rectifier bridge, an input
capacitor, an
inductor, a
bus capacitor, a first
diode, a switching tube, a second
diode, a sampling
resistor and a
transformer, wherein the first end of the
inductor is connected with the first end of the input
capacitor, and the first end of the
bus capacitor is connected with the second end of the
inductor; the
anode of the first
diode is connected with the second end of the
bus capacitor, and the
cathode of the first diode is connected with the negative output end of the
rectifier bridge; the first power end of the switching tube is connected with the second end of the inductor, and the control end of the switching tube receives the external driving signals; the
anode of the second diode is connected with the second power end of the switching tube, and the
cathode of the second diode is connected with the negative output end of the
rectifier bridge; the first end of the sampling
resistor is connected with the second power end of the switching tube, and the dotted terminal of the primary side winding of the
transformer is connected with the second end of the sampling
resistor; and the non-dotted terminal of the primary side winding of the
transformer is connected with the second end of the bus capacitor, and the transformer is coupled with a load. The circuit provided by the invention has the
advantage of lower cost compared with the traditional two-stage circuit, and has the
advantage of reduction in
ripple current of the load compared with the traditional single-stage circuit.