Abstract: A power conversion control circuit, which is applied to a flyback converter having a main switch, includes at least one bypass switch, a half-bridge power control unit, and an active-clamp control unit. The half-bridge power control unit is coupled to the main switch. The active-clamp control unit is coupled to the half-bridge power control unit and the main switch. When the flyback converter is operated in light-load condition, the active-clamp control unit turns on the at least one bypass switch, the half-bridge power control unit is coupled to the ground through the at least one bypass switch, the active-clamp control unit is coupled to the ground through the main switch, and the active-clamp control unit provides a low-side control signal to switch the main switch. Accordingly, it is to make the flyback converter have considerable power saving and energy saving in light-load condition.

Abstract: An adapter includes a rectifying unit, a power factor correction unit, a standby circuit, a load-connecting detection circuit, a first power conversion circuit, a second power conversion circuit and an auxiliary voltage control circuit. When a load apparatus is connected to the adapter, a first ground side of the first power conversion circuit is short-circuited to a second ground side of the second power conversion circuit, so that the load-connecting detection circuit is turned on and sends out a first signal. After the auxiliary voltage control circuit receives the first signal, the auxiliary voltage control circuit is turned on to drive the first power conversion circuit and the second power conversion circuit, so that the first power conversion circuit and the second power conversion circuit start to convert a first voltage into a first output voltage and a second output voltage.

Abstract: A multi-channel LED driving system includes a power adapter, a rectifying and filtering unit, a plurality of LED strings, and a plurality of linear regulators, a CC/CV controller, an optically coupled isolator and a PWM controller. The CC/CV controller detects the conducting currents flowing though the LED strings and DC voltage source outputting from the rectifying and filtering unit, and provides voltage compensation of the power adaptor. In addition, the linear regulators slightly modulate the current difference between the LED strings to achieve current-sharing control, thus stabilize the illuminating brightness generating by the LED.

Abstract: A multi-channel LED driving system includes a power adapter, a rectifying and filtering unit, a plurality of LED strings, and a plurality of linear regulators, a CC/CV controller, an optically coupled isolator and a PWM controller. The CC/CV controller detects the conducting currents flowing though the LED strings and DC voltage source outputting from the rectifying and filtering unit, and provides voltage compensation of the power adaptor. In addition, the linear regulators slightly modulate the current difference between the LED strings to achieve current-sharing control, thus stabilize the illuminating brightness generating by the LED.