Patent ID: 8278832

Claim:
An isolated voltage generator adapted to a light-emitting diode (LED) dimmer circuit, the LED dimmer circuit having a triac dimmer, and the isolated voltage generator comprising: a rectifier, receiving a first voltage modulated by the triac dimmer; a controller, having an input terminal, a driving output terminal, a feedback terminal and a current sensing terminal, the controller generating a control signal according to voltages received by the feedback terminal and the current sensing terminal, and outputting the control signal through the driving output terminal; a transformer, having a first side winding, a second side winding and a third side winding, wherein a first terminal of the first side winding is coupled to the rectifier, a first terminal of the second side winding outputs a driving signal, a second terminal of the second side winding is coupled to a second ground voltage, and the third side winding is coupled between the input terminal of the controller and a first ground voltage; a switch, having a control terminal, a first terminal and a second terminal, the control terminal of the switch being coupled to the driving output terminal of the controller, the first terminal of the switch being coupled to a second terminal of the first side winding, and the second terminal of the switch being coupled to the current sensing terminal of the controller; a voltage divider, coupled among a first terminal of the third side winding of the transformer, the feedback terminal of the controller and the first ground voltage, for providing a divided voltage to the feedback terminal of the controller; and a first resistor, coupled between the current sensing terminal of the controller and the first ground voltage.