Abstract: Provided in an embodiment of the present invention are an LED driver, and method and device for controlling the fixed value of the LED driver, the method comprising: detecting whether an existing terminal of an LED driver inputs a control signal; when the control signal is detected, determining the fixed value of the LED driver according to the control signal; when the LED driver is an LED driver having no dimming function, the fixed value is the rated current of the LED driver; when the LED driver is an LED driver having a dimming function, the fixed value includes the upper limit or lower limit of the output current value of the LED driver. The method, device and the LED driver provided in the embodiment of the present invention can save LED driver costs.

Abstract: A converter includes a transformer having a primary winding, a secondary winding and an auxiliary winding, a first switching device for connecting an input voltage to the primary winding of the transformer, an output circuit connected to the secondary winding, a controller, and an integrated active clamp and primary bias circuit. The integrated active clamp and primary bias circuit includes the auxiliary winding and a second switch providing a bias voltage to the controller to alternately operate the first and second switches between conductive and non-conductive states. When the first switch is conductive the second switch is nonconducting and power is transferred from the primary winding to the output circuit via the secondary winding and from the auxiliary winding to the controller. When the first switch is nonconducting, the second switch is conducting and the voltage across the primary winding is clamped.

Abstract: A converter includes a transformer having a primary winding, a secondary winding and an auxiliary winding, a first switching device for connecting an input voltage to the primary winding of the transformer, an output circuit connected to the secondary winding, a controller, and an integrated active clamp and primary bias circuit. The integrated active clamp and primary bias circuit includes the auxiliary winding and a second switch providing a bias voltage to the controller to alternately operate the first and second switches between conductive and non-conductive states. When the first switch is conductive the second switch is nonconducting and power is transferred from the primary winding to the output circuit via the secondary winding and from the auxiliary winding to the controller. When the first switch is nonconducting, the second switch is conducting and the voltage across the primary switch is clamped.