Abstract: A phase cut dimming LED driver includes a rectifier, a phase cut hold, a local regulator, controller, a power switch, a transformer, and a load detector. The phase cut hold is connected to the rectifier, one terminal of the primary winding of the transformer, and the local regulator. The controller includes pins connected to the local regulator, the power switch, and the aux winding of the transformer. The power switch is connected to the other terminal of the primary winding. The load detector is connected between the secondary winding of the transformer and a LED. The load detector sends the voltage or current signal of the LED to the controller, and the controller controls the power switch in an uninterrupted mode to keep the current or voltage in a condition to obtain higher PF and lower THD.

Abstract: In one embodiment, an output transistor and a bias compensation device are placed in proximity to each other on the same package substrate. The bias compensation device is electrically isolated but thermally coupled to the output transistor, and is configured to provide a output signal for adjusting bias to the output transistor.