Abstract: A switching power supply circuit includes a power circuit, a switching circuit and a load. The switching circuit includes a first filter module, a power processing unit, a stability module, and a second filter module. The first filter module receives a voltage signal from the power circuit and sends a filtered first voltage signal to the power processing unit; the power processing unit outputs a second voltage signal, the stability module stabilizes the second voltage signal and sends a third voltage signal to the second filter module; the second filter module filters the third voltage signal and sends a drive voltage to the load. In response to the second voltage signal instantaneously changing from high to low or low to high, during the change in current, power of the second voltage signal is stored in the stability module and released through the second filter module.

Abstract: An exemplary power circuit includes a first rectifying and filtering circuit, a power factor correction (PFC) circuit, an inverter circuit and a second rectifying and filtering circuit. The first rectifying and filtering circuit receives an AC voltage and transforms the AC voltage to a first DC voltage. The power factor correction circuit includes a first transformer, a first diode and a first storage capacitor. The inverter circuit includes a transistor and a second transformer. A primary winding of the second transformer is grounded via the transistor and receives the first DC voltage via a primary winding of the first transformer, the first diode and a secondary winding of the first transformer in series when the transistor is switched on. The second rectifying and filtering circuit connected to a secondary winding of the second transformer for providing a second DC voltage to a load circuit.

Abstract: A switching power supply circuit includes a direct current (DC) power supply input, a first transistor, a capacitor, a first resistor, a second resistor, a switching circuit including a second transistor, and a first transformer including a first primary winding and a secondary winding. The DC power supply input is connected to a drain electrode of the first transistor via the capacitor. A gate electrode of the first transistor is connected to ground via the first resistor, and connected to the drain electrode of the first transistor via the second resistor. The DC power supply input is connected to a source electrode of the first transistor via the primary winding. The source electrode of the first transistor is grounded via the second transistor. The secondary winding is structured and arranged to drive a load circuit.

Abstract: An exemplary circuit (200) for driving light sources (211, 212, 213, 214) includes feedback circuits (218, 228, 238, 248), a signal balance circuit, and a controller (250). Each feedback circuit corresponds to a light source and is configured for providing a first feedback signal according to a driving current of the light source. The signal balance circuit is configured for balancing all the first feedback signals and correspondingly generating a second feedback signal. The controller is configured for driving the light sources to illuminate according to the second feedback signal.

Abstract: A switching power supply circuit includes a direct current (DC) power supply input terminal, a first transformer including a first primary winding, a second transformer, and a pulse generating circuit, and a startup circuit. The pulse generating circuit includes first and second first switching units connected in series and two voltage division resistors connected in series between the DC power supply input terminal and ground, and two capacitors connected in parallel with one of the two voltage division resistors. The second transformer includes a second primary winding connected between control terminal and second conducting terminal of the first switching unit, a second secondary winding; and an assistant winding connected between the control terminal of the second switching unit and ground. The second conducting terminal of the first switching unit is grounded via the second secondary winding, the first primary winding and a capacitor in series.

Abstract: A switching power supply circuit includes a power circuit, a switching circuit and a load. The switching circuit includes a first filter module, a power processing unit, a stability module, and a second filter module. The first filter module receives a voltage signal from the power circuit and sends a filtered first voltage signal to the power processing unit; the power processing unit outputs a second voltage signal, the stability module stabilizes the second voltage signal and sends a third voltage signal to the second filter module; the second filter module filters the third voltage signal and sends a drive voltage to the load. In response to the second voltage signal instantaneously changing from high to low or low to high, during the change in current, power of the second voltage signal is stored in the stability module and released through the second filter module.

Abstract: An exemplary DC to DC converter (2) includes a transistor (29), a first rectifying and filtering circuit (21), a pulse generating circuit (27) and a transformer (25). The first rectifying and filtering circuit transforms an external AC voltage to a first DC voltage. The transformer includes a primary winding (251), an assistant winding (252) connected with the primary winding in a flyback mode, and a secondary winding (253). The first DC voltage is connected to ground via the primary winding, the transistor in series. The pulse generating circuit includes a controlling terminal, a diode, a resistor, and a capacitor. One terminal of the assistant winding is connected to ground, and the other terminal of the assistant winding is connected to an anode of the diode. A cathode of the diode is connected to ground via the resistor and the capacitor in series. The controlling terminal is connected to gate electrode of the transistor.

Abstract: An exemplary power supply control circuit (200) includes a first port (201), a second port (202), a third port (203), a controllable switch (280), and a control circuit (270). The first and second ports are configured to receive a power supply voltage signal. The second and third ports are configured to output the power supply voltage signal to a load circuit. The controllable switch includes a control member (281) and a switch member (282). The control circuit is configured to control a working state of the control member. When the load circuit stops working, the control circuit controls the control member to control the switch member to be disconnected, so as to cut off the power supply voltage signal from outputting to the load circuit. A liquid crystal display (400) using the power supply control circuit is also provided.

Abstract: A power circuit includes a transformer, a full-bridge rectifier and a feedback circuit. The transformer is used to input an external AC voltage. The transformer includes a plurality of output terminals. The output terminals include a plurality of output terminal combinations, and at least two different output terminal combinations output a first AC voltage and a second AC voltage. The full-bridge rectifier is used to convert the first AC voltage or the second AC voltage into DC voltages. The feedback circuit makes the transformer switch between different output ports combinations according to the value of the second AC voltage.

Abstract: A switching power supply circuit includes a direct current (DC) power supply input; a voltage divider connected between the DC power supply input and ground; a transformer including a primary winding, a secondary winding, and an assistant winding; a pulse generating circuit including a first transistor, a second transistor, an oscillation capacitor, and an oscillation resistor; an output; and a feedback circuit adjusting a duty ratio of a pulse signal in the assistant winding. The DC power supply input is grounded via the primary winding, two conducting electrodes of the second transistor. A control electrode of the second transistor is connected to an output of the voltage divider. An output of the voltage divider is connected to a control electrode of the second transistor and is grounded via two conducting electrodes. A control electrode of the first transistor is grounded via the assistant winding and grounded via the oscillation capacitor and the oscillation resistor connected in series.

Abstract: A switching power supply circuit includes a direct current (DC) power supply input, a first transistor, a capacitor, a first resistor, a second resistor, a switching circuit including a second transistor, and a first transformer including a first primary winding and a secondary winding. The DC power supply input is connected to a drain electrode of the first transistor via the capacitor. A gate electrode of the first transistor is connected to ground via the first resistor, and connected to the drain electrode of the first transistor via the second resistor. The DC power supply input is connected to a source electrode of the first transistor via the primary winding. The source electrode of the first transistor is grounded via the second transistor. The secondary winding is structured and arranged to drive a load circuit.

Abstract: A switching power supply circuit includes a direct current (DC) power supply input terminal, a first transformer including a first primary winding, a second transformer, and a pulse generating circuit, and a startup circuit. The pulse generating circuit includes first and second first switching units connected in series and two voltage division resistors connected in series between the DC power supply input terminal and ground, and two capacitors connected in parallel with one of the two voltage division resistors. The second transformer includes a second primary winding connected between control terminal and second conducting terminal of the first switching unit, a second secondary winding; and an assistant winding connected between the control terminal of the second switching unit and ground. The second conducting terminal of the first switching unit is grounded via the second secondary winding, the first primary winding and a capacitor in series.

Abstract: An exemplary power circuit includes a first rectifying and filtering circuit, a power factor correction (PFC) circuit, an inverter circuit and a second rectifying and filtering circuit. The first rectifying and filtering circuit receives an AC voltage and transforms the AC voltage to a first DC voltage. The power factor correction circuit includes a first transformer, a first diode and a first storage capacitor. The inverter circuit includes a transistor and a second transformer. A primary winding of the second transformer is grounded via the transistor and receives the first DC voltage via a primary winding of the first transformer, the first diode and a secondary winding of the first transformer in series when the transistor is switched on. The second rectifying and filtering circuit connected to a secondary winding of the second transformer for providing a second DC voltage to a load circuit.

Abstract: An exemplary circuit (200) for driving light sources (211, 212, 213, 214) includes feedback circuits (218, 228, 238, 248), a signal balance circuit, and a controller (250). Each feedback circuit corresponds to a light source and is configured for providing a first feedback signal according to a driving current of the light source. The signal balance circuit is configured for balancing all the first feedback signals and correspondingly generating a second feedback signal. The controller is configured for driving the light sources to illuminate according to the second feedback signal.

Abstract: An exemplary power supply circuit (200) includes a transformer (240), a first transistor (260), a start-up resistor (261), and a pulse generating circuit (250). The transformer includes a primary winding (241), a secondary winding (243), and an auxiliary winding (242). The first bipolar junction transistor includes a collector connected to a first terminal of the primary winding and an emitter grounded. The start-up resistor is connected between a second terminal of the primary winding and a base of the bipolar junction transistor. The pulse generating circuit is configured for generating a control signal according to an induction voltage of the auxiliary winding. The control signal is provided to the base of the first bipolar junction transistor for switching the first bipolar junction transistor.

Abstract: An exemplary DC to DC converter (2) includes a transistor (29), a first rectifying and filtering circuit (21), a pulse generating circuit (27) and a transformer (25). The first rectifying and filtering circuit transforms an external AC voltage to a first DC voltage. The transformer includes a primary winding (251), an assistant winding (252) connected with the primary winding in a flyback mode, and a secondary winding (253). The first DC voltage is connected to ground via the primary winding, the transistor in series. The pulse generating circuit includes a controlling terminal, a diode, a resistor, and a capacitor. One terminal of the assistant winding is connected to ground, and the other terminal of the assistant winding is connected to an anode of the diode. A cathode of the diode is connected to ground via the resistor and the capacitor in series. The controlling terminal is connected to gate electrode of the transistor.

Abstract: An exemplary power supply control circuit (200) includes a first port (201), a second port (202), a third port (203), a controllable switch (280), and a control circuit (270). The first and second ports are configured to receive a power supply voltage signal. The second and third ports are configured to output the power supply voltage signal to a load circuit. The controllable switch includes a control member (281) and a switch member (282 ). The control circuit is configured to control a working state of the control member. When the load circuit stops working, the control circuit controls the control member to control the switch member to be disconnected, so as to cut off the power supply voltage signal from outputting to the load circuit. A liquid crystal display (400) using the power supply control circuit is also provided.