Abstract: A drive circuit with a zero-crossing detection function, and a zero-crossing detection method. The drive circuit comprises: a power switch transistor, a pull-up drive transistor, a first pull-down drive transistor and a second pull-down drive transistor. When an inductor starts to discharge, the first pull-down current and the second pull-down current jointly pull down a gate terminal of the power switch transistor, such that the power switch transistor is in a cut-off state; after a set time, the first pull-down current is turned off; and when the inductor ends discharging, a parasitic capacitance of the power switch transistor couples with the drop signal, and when the drop signal is detected, the pull-up current pulls up the gate terminal of the power switch transistor, such that the power switch transistor is in a turn-on state.

Abstract: A drive circuit with a zero-crossing detection function, and a zero-crossing detection method. The drive circuit comprises: a power switch transistor, a pull-up drive transistor, a first pull-down drive transistor and a second pull-down drive transistor. When an inductor starts to discharge, the first pull-down current and the second pull-down current jointly pull down a gate terminal of the power switch transistor, such that the power switch transistor is in a cut-off state; after a set time, the first pull-down current is turned off; and when the inductor ends discharging, a parasitic capacitance of the power switch transistor couples with the drop signal, and when the drop signal is detected, the pull-up current pulls up the gate terminal of the power switch transistor, such that the power switch transistor is in a turn-on state.

Abstract: A LED driving circuit and method for balancing efficiency and a power factor. The circuit comprises a voltage input module, an LED load, a constant current control module and a current turn-off slope control module for adjusting the turn-off slope of the current flowing through the LED load, such that a compromise between efficiency and power factor is achieved. When an input voltage is higher than a setting voltage, the current flowing through the LED load is turned off, such that the power consumption is reduced; in addition, the efficiency and power factor are balanced by adjusting the turn-off slope of the current. According to the present invention, a compensation capacitor is used to control the average current in an alternating current period and to limit peak current, thereby implementing constant power output within a wide range of input voltage.

Abstract: A LED driving circuit and method for balancing efficiency and a power factor. The circuit comprises a voltage input module, an LED load, a constant current control module and a current turn-off slope control module for adjusting the turn-off slope of the current flowing through the LED load, such that a compromise between efficiency and power factor is achieved. When an input voltage is higher than a setting voltage, the current flowing through the LED load is turned off, such that the power consumption is reduced; in addition, the efficiency and power factor are balanced by adjusting the turn-off slope of the current. According to the present invention, a compensation capacitor is used to control the average current in an alternating current period and to limit peak current, thereby implementing constant power output within a wide range of input voltage.