Abstract: According to some embodiments, AC chopping circuit includes a switching circuit, a synchronizing signal generating circuit, a switch driving circuit and an auxiliary power supplying circuit. In some examples, the switching circuit are coupled to an AC power source and a load. In certain examples, the synchronizing signal generating circuit provides a synchronizing signal which is related to a polarity of the AC power source. In some examples, the switching circuit is controlled based at least in part on the synchronizing signal.

Abstract: According to some embodiments, AC chopping circuit includes a switching circuit, a synchronizing signal generating circuit, a switch driving circuit and an auxiliary power supplying circuit. In some examples, the switching circuit are coupled to an AC power source and a load. In certain examples, the synchronizing signal generating circuit provides a synchronizing signal which is related to a polarity of the AC power source. In some examples, the switching circuit is controlled based at least in part on the synchronizing signal.

Abstract: According to some embodiments, AC chopping circuit includes a switching circuit, a synchronizing signal generating circuit, a switch driving circuit and an auxiliary power supplying circuit. In some examples, the switching circuit are coupled to an AC power source and a load. In certain examples, the synchronizing signal generating circuit provides a synchronizing signal which is related to a polarity of the AC power source. In some examples, the switching circuit is controlled based at least in part on the synchronizing signal.

Abstract: A control circuit for controlling a power transistor is provided. The power transistor is coupled in series with a load, both coupled between an input power terminal and a reference ground. The control circuit controls the conduction state of the power transistor based on a dimming signal, and when a representative value of the dimming signal is higher than a first threshold, the control circuit regulates the amplitude of the current flowing through the power transistor, and when the representative value of the dimming signal is lower than a second threshold, the control circuit regulates the time of the current flowing through the power transistor, and wherein the second threshold is not higher than the first threshold.

Abstract: A control circuit for controlling a transistor includes a reference signal generating circuit and a driver stage circuit. The reference signal generating circuit outputs a reference signal, and to control the reference signal having a first change trend in a first time period of a time interval and having a second change trend in a second time period of the time interval based on time. The driver stage circuit is configured to control the transistor according to the reference signal and a current sampling signal, so that the current flowing through the transistor changes with the reference signal.

Abstract: A stepless motor driving circuit provides a sinusoidal shaped chopping signal for driving a motor. The driving circuit has: a switch circuit having an input which receives a rectified signal rectified from a sinusoidal AC signal and having a first output and a second output where the motor is coupled between; a synchronizing signal generating circuit which generates a synchronizing signal relating to the sinusoidal AC signal; and a switch driving circuit which selects and chops at least one switch in the switch circuit according to the synchronizing signal, and to form the sinusoidal shaped chopping signal which is corresponding to the sinusoidal AC signal.