Abstract: An exemplary direct current (DC) to DC converter includes a first rectifying and filtering circuit configured to receive an alternating current (AC) voltage and transform the AC voltage to a first DC voltage, a pulse width modulation (PWM) circuit, a first transformer configured to receive the first DC voltage and transform the first DC voltage to a second AC voltage under control of the PWM circuit, and a second rectifying and filtering circuit including a first transistor and a control circuit for switching on or switching off the first transistor so as to transform the second AC voltage to a second DC voltage.

Abstract: An exemplary multiplexed direct current regulation output circuit (2) includes a feedback circuit (22), a sampling circuit (30), a power control chip (21), a first output (27), a second output (28), a first half wave rectifier circuit (23), a second half wave rectifier circuit (24), a first filter circuit (25), a second filter circuit (26), a transformer (20), and a balance control circuit (29). The transformer is configured to provide low voltages to the first output via the first half wave rectifier circuit and the first filter circuit in series, and provide high voltages to the second output via the second half wave rectifier circuit and the second filter circuit in series. The balance control circuit is configured to control a voltage at the second output.

Abstract: An exemplary DC to DC converter (200) includes a first DC input (210) connected to a first DC power supply; a second DC input (220) connected to a second DC power supply; a transformer (230) including a primary winding (231), a sub-primary winding (232), and a secondary winding (233) for outputting a AC voltage; a pulse reverse circuit (260) including an input for receiving a square pulse and an output for providing the reverse square pulse; a first switch transistor (240) including a source connected to ground, a drain connected to the first DC input via the primary winding, and a gate connected to the output of the pulse reverse circuit; a second switch transistor (250) including a source connected to ground, a drain connected to ground via the sub-primary winding and a capacitor in series, and a gate connected to the output of the pulse reverse circuit.

Abstract: An exemplary power supply circuit (20) includes a first commutating and filter circuit (21), a transformer (24), a second commutating and filter circuit (25), a transistor (27), a pulse width modulation circuit (26) outputting a control signal to control operation state of the transistor, and a feedback circuit (29). An external alternating current voltage is converted into a direct current with a cooperation operating of the transistor, the first commutating and filter circuit, the transformer, and the second commutating and filter circuit. The feedback circuit feeds an operating state of the transformer back to the pulse width modulation circuit, and the pulse width modulation circuit outputs corresponding control signals to turn on or turn off the transistor.

Abstract: An exemplary direction current (DC) to DC converter includes a first rectifying and filtering circuit configured to receive an alternating current (AC) voltage and transform the AC voltage to a first DC voltage, a pulse width modulation (PWM) circuit, a first transformer configured to receive the first DC voltage and transform the first DC voltage to a second AC voltage under control of the PWM circuit, and a second rectifying and filtering circuit including a first transistor and a control circuit for switching on or switching off the first transistor so as to transform the second AC voltage to a second DC voltage.

Abstract: An exemplary switching power supply circuit includes at least a power input terminal, a power control chip, and a soft start circuit. The power input terminal is configured for receiving an operating voltage applied to the switching power supply circuit, and the power control chip is configured for modulating a pulse width of an output current of an optical coupler in the soft start circuit to gain a pulse width voltage of the switching power supply circuit. The soft start circuit includes a first resistor, a second resistor, a capacitor, and a transistor performing an amplifying function.

Abstract: An exemplary multiplexed direct current regulation output circuit (2) includes a feedback circuit (22), a sampling circuit (30), a power control chip (21), a first output (27), a second output (28), a first half wave rectifier circuit (23), a second half wave rectifier circuit (24), a first filter circuit (25), a second filter circuit (26), a transformer (20), and a balance control circuit (29). The transformer is configured to provide low voltages to the first output via the first half wave rectifier circuit and the first filter circuit in series, and provide high voltages to the second output via the second half wave rectifier circuit and the second filter circuit in series. The balance control circuit is configured to control a voltage at the second output.

Abstract: An exemplary power supply circuit (20) includes a first commutating and filter circuit (21), a transformer (24), a second commutating and filter circuit (25), a transistor (27), a pulse width modulation circuit (26) outputting a control signal to control operation state of the transistor, and a feedback circuit (29). An external alternating current voltage is converted into a direct current with a cooperation operating of the transistor, the first commutating and filter circuit, the transformer, and the second commutating and filter circuit. The feedback circuit feeds an operating state of the transformer back to the pulse width modulation circuit, and the pulse width modulation circuit outputs corresponding control signals to turn on or turn off the transistor.

Abstract: An exemplary multi-output switching power supply (2) includes: a switching power supply controller (21) for generating a pulse signal; a transformer device (20) for providing a first AC voltage and a second AC voltage according to the pulse signal; a first regulation circuit (23, 25) for transforming the first AC voltage into a first DC voltage; a second regulation circuit (24, 26) for transforming the second AC voltage into a second DC voltage; a first output (27) and a second output (28) for respectively providing the first DC voltage and second DC voltage to a heavy load and a light load; a sampling circuit and a feedback circuit configured for generating a feedback signal according to the first DC voltage and the second DC voltage and providing the feedback signal to the switching power supply controller, and a voltage limiting circuit (29) connected between the first and second outputs.

Abstract: An exemplary multi-output switching power supply (2) includes a switching power supply controller (21) for generating a pulse signal; a transformer device (20) for providing a first and a second AC voltages according to the pulse signal; a first half wave rectifier (23) and a first filter circuit (25) connected in series for transforming the first AC voltage to a first DC voltage; a second half wave rectifier (24) and a second filter circuit (26) connected in series for transforming the second AC voltage to a second DC voltage; a first output (27) for providing the first DC voltage to a first load circuit (210); a feedback circuit configured for generating a feedback signal according to the first DC voltage and the second DC voltage, and providing the feedback signal to the switching power supply controller; and a voltage limiting circuit (29) connected between the first output and ground.

Abstract: An open protection circuit (300) for a backlight module includes a PWM (350) with a control port (351) to disable the PWM. A switch (371) has a gate and a source connected to the control port. A plurality of first input circuits (330) includes first diodes (331), each of which has a first positive terminal connected to the gate and a negative terminal connected to ground. A plurality of second input circuits (340) include input resistors (341) connected to the control port. A plurality of detecting circuits (310, 380) are connected to the fluorescent lamps (311) and the first and second input circuits respectively. Each detecting circuit includes a sampling resistor (313) connected to one of the negative terminals of the first diodes, thereby the control port of the PWM is pulled low when either one of the fluorescent lamps are open-circuit.

Abstract: An exemplary DC to DC converter (200) includes a first DC input (210) connected to a first DC power supply; a second DC input (220) connected to a second DC power supply; a transformer (230) including a primary winding (231), a sub-primary winding (232), and a secondary winding (233) for outputting a AC voltage; a pulse reverse circuit (260) including an input for receiving a square pulse and an output for providing the reverse square pulse; a first switch transistor (240) including a source connected to ground, a drain connected to the first DC input via the primary winding, and a gate connected to the output of the pulse reverse circuit; a second switch transistor (250) including a source connected to ground, a drain connected to ground via the sub-primary winding and a capacitor in series, and a gate connected to the output of the pulse reverse circuit.

Abstract: An open protection circuit (300) for a backlight module includes a PWM (350) with a control port (351) to disable the PWM. A switch (371) has a gate and a source connected to the control port. A plurality of first input circuits (330) includes first diodes (331), each of which has a first positive terminal connected to the gate and a negative terminal connected to ground. A plurality of second input circuits (340) include input resistors (341) connected to the control port. A plurality of detecting circuits (310, 380) are connected to the fluorescent lamps (311) and the first and second input circuits respectively. Each detecting circuit includes a sampling resistor (313) connected to one of the negative terminals of the first diodes, thereby the control port of the PWM is pulled low when either one of the fluorescent lamps are open-circuit.