Abstract: An exemplary power supply switching circuit (200) includes a first input (210) for receiving a first signal, a second input (220) for receiving a second signal, a voltage regulating circuit (240), and a signal switching circuit (250). The voltage regulating circuit includes semiconductor elements (241) electrically coupled in series. The signal switching circuit includes a first input terminal (253), a second input terminal (254), and an output terminal (255). The first input is electrically coupled to the first input terminal via the first voltage regulating circuit, the second input is electrically coupled to the second input terminal, and the output terminal is configured to be an output of the power supply switching circuit. The first voltage regulating circuit regulates the first signal via the voltage drops of the first semiconductor elements. A flat panel display using the power supply switching circuit is also provided.

Abstract: An exemplary DC to DC converter includes a first transistor, a second transistor, a transformer, and a pulse generating circuit having a first capacitor, a sampling resistor, a zener diode, and a first diode. A DC voltage input terminal is configured for receiving a first DC voltage and is grounded via the primary winding of the transformer, a collector electrode and an emitter electrode of the first transistor in series. A terminal of the auxiliary winding of the transformer is grounded via the inverted first diode, the non-inverted zener diode, the sampling resistor, and the first capacitor. The other terminal of the auxiliary winding is grounded. A first transistor having a base electrode connected to the DC voltage input terminal. A second transistor includes an emitter electrode a cathode of the zener diode, a collector electrode connected to a base electrode of the first transistor, and a grounded base electrode.

Abstract: An exemplary power switching circuit (20) includes a control signal input terminal (210); an output terminal (220); direct current (DC) power supply (230); a first transistor (250) including a control electrode connected to the control signal input terminal, a first current conducting electrode, and a grounded second current conducting electrode; a second transistor (260) including a control electrode connected to first current conducting electrode of the first transistor via a discharging resistor (264) and a diode (266) respectively and connected to the DC power supply via a discharging capacitor (265), a first current conducting electrode connected to the DC power supply, and a second current conducting electrode connected to the output terminal; and a third transistor (270) including a control electrode connected to first current conducting electrode of the first transistor, a first current conducting electrode connected to the output terminal, and a second grounded current conducting electrode.

Abstract: An exemplary DC to DC converter includes a first transistor, a second transistor, a transformer, and a pulse generating circuit having a first capacitor, a sampling resistor, a zener diode, and a first diode. A DC voltage input terminal is configured for receiving a first DC voltage and is grounded via the primary winding of the transformer, a collector electrode and an emitter electrode of the first transistor in series. A terminal of the auxiliary winding of the transformer is grounded via the inverted first diode, the non-inverted zener diode, the sampling resistor, and the first capacitor. The other terminal of the auxiliary winding is grounded. A first transistor having a base electrode connected to the DC voltage input terminal. A second transistor includes an emitter electrode a cathode of the zener diode, a collector electrode connected to a base electrode of the first transistor, and a grounded base electrode.

Abstract: A drive circuit of a computer system is for driving a mode indicator. The computer system includes a first port and a second port. The mode indicator includes a first receiving end and a second receiving end. The drive circuit includes a first input end connected to the first port, a second input end connected to the second port, a first output end connected to the first receiving end, a second output end connected to the second receiving end. A power supply is connected to the first input end and the second input end via a first resistor and a second resistor respectively. The mode indicator is dichromatic and has two LEDs emitting non-matching colored light.

Abstract: An exemplary power switching circuit (20) includes a control signal input terminal (210); an output terminal (220); direct current (DC) power supply (230); a first transistor (250) including a control electrode connected to the control signal input terminal, a first current conducting electrode, and a grounded second current conducting electrode; a second transistor (260) including a control electrode connected to first current conducting electrode of the first transistor via a discharging resistor (264) and a diode (266) respectively and connected to the DC power supply via a discharging capacitor (265), a first current conducting electrode connected to the DC power supply, and a second current conducting electrode connected to the output terminal; and a third transistor (270) including a control electrode connected to first current conducting electrode of the first transistor, a first current conducting electrode connected to the output terminal, and a second grounded current conducting electrode.

Abstract: An exemplary power supply circuit (200) includes a rectifying circuit (240), a filter circuit (280), and a voltage stabling circuit (250). The rectifying circuit is configured to convert an alternating current voltage signal to a direct current voltage signal. The filter circuit is configured to filter the direct current voltage signal, and includes a first filter member (201) and a second filter member (202). The voltage stabling circuit is configured to stabilize the direct current voltage signal being filtered by the filter circuit. The filter circuit filters the direct current voltage signal via alternately charging and discharging the first and second filter members. The first and second filter members are electrically coupled in series during the charging process, and electrically coupled in parallel during the discharging process. A liquid crystal display (400) using the power supply circuit is also provided.

Abstract: An exemplary power supply switching circuit (200) includes a first input (210) for receiving a first signal, a second input (220) for receiving a second signal, a voltage regulating circuit (240), and a signal switching circuit (250). The voltage regulating circuit includes semiconductor elements (241) electrically coupled in series. The signal switching circuit includes a first input terminal (253), a second input terminal (254), and an output terminal (255). The first input is electrically coupled to the first input terminal via the first voltage regulating circuit, the second input is electrically coupled to the second input terminal, and the output terminal is configured to be an output of the power supply switching circuit. The first voltage regulating circuit regulates the first signal via the voltage drops of the first semiconductor elements. A flat panel display using the power supply switching circuit is also provided.

Abstract: An exemplary voltage stabilizing circuit (2) includes a voltage input port (20), a voltage output port (21), a first transistor (22), a constant current circuit (23), and a feedback control circuit (24). The first transistor has a first base (221), a first emitter (222) connected to the output port, and a first collector (223) connected to the input port. The feedback control circuit has a resistor (244), a branch circuit (245-247), a voltage stabilizing unit (242), and a second transistor (241). The second transistor has a second emitter (2412) connected to ground via the voltage stabilizing unit and connected to the output port, a second collector (2413) connected to the first base of the first transistor, and a second base (2411) connected to the branch circuit. The constant current circuit provides current to the first base of the first transistor and the second collector of the second transistor.

Abstract: An exemplary backlight control circuit (200) includes two load circuits (210), a pulse width modulation integrated circuit (PWM IC) (250) having a current sampling pin (251), a switching circuit (270), a first input circuit (230) and a second input circuit (240) including an input resistor. Each load circuit includes a backlight (211, 221) and an output end (212, 222). The first input circuit includes a diode (231), a resistor (232), a capacitor (233) and a voltage division resistor (234). A negative terminal of the diode is connected to ground via the resistor and the capacitor respectively, and is connected to the switching circuit. A positive terminal of the diode is connected to one of the output end of the load circuits. The other one of the output ends of the load circuits is connected to the current sampling pin via the input resistor.

Abstract: A drive circuit of a computer system is for driving a mode indicator. The computer system includes a first port and a second port. The mode indicator includes a first receiving end and a second receiving end. The drive circuit includes a first input end connected to the first port, a second input end connected to the second port, a first output end connected to the first receiving end, a second output end connected to the second receiving end, a power supply, a first transistor connected between the first input end and the power supply, and a second transistor connected between the second input end and the power supply. Collectors of the first and second transistors are separately connected to the first and second output ends. The mode indicator is dichromatic and has two LEDs emitting non-matching colored light.

Abstract: A power supplying and discharging circuit (20) for a liquid crystal display includes a direct current source (230), a control signal input (210) configured for providing a control signal, a supply-discharge terminal (220) configured for supplying and discharging electricity for the liquid crystal display, an NPN type transistor (240), a PMOS type transistor (250), a bias resistor (255), and a discharging resistor (266). The NPN type transistor includes a base connected to the control signal input, an emitter connected to ground, and a collector connected to the direct current source via the bias resistor. The PMOS type transistor includes a gate electrode connected to the collector of the NPN type transistor, a source electrode connected to the direct current source, and a drain electrode connected to the supply-discharge terminal. The supply-discharge terminal is connected to ground via the discharging resistor.

Abstract: An exemplary power switching circuit (20) includes a control signal input terminal (210) which is configured for receiving a control signal; an output terminal (220) configured to be connected to a load circuit with capacitance; a direct current (DC) power supply (230); a first switching transistor (240) including a control electrode connected to the control signal input terminal, a first current conducting electrode, and a grounded second current conducting electrode; a second switching transistor (250) including a control electrode connected to the first current conducting electrode of the first switching transistor, a first current conducting electrode connected to the DC power supply, and a second current conducting electrode connected to the output terminal; and a third switching transistor (260) including a control electrode connected to the control signal input terminal, a first current conducting electrode connected to the output terminal, and a grounded second current conducting electrode.

Abstract: An exemplary backlight control circuit (200) includes two load circuits (210), a pulse width modulation integrated circuit (PWM IC) (250) having a current sampling pin (251), a switching circuit (270), a first input circuit (230) and a second input circuit (240) including an input resistor. Each load circuit includes a backlight (211, 221) and an output end (212, 222). The first input circuit includes a diode (231), a resistor (232), a capacitor (233) and a voltage division resistor (234). A negative terminal of the diode is connected to ground via the resistor and the capacitor respectively, and is connected to the switching circuit. A positive terminal of the diode is connected to one of the output end of the load circuits. The other one of the output ends of the load circuits is connected to the current sampling pin via the input resistor.

Abstract: A drive circuit of a computer system is for driving a mode indicator. The computer system includes a first port and a second port. The mode indicator includes a first receiving end and a second receiving end. The drive circuit includes a first input end connected to the first port, a second input end connected to the second port, a first output end connected to the first receiving end, a second output end connected to the second receiving end, a power supply, a first transistor connected between the first input end and the power supply, and a second transistor connected between the second input end and the power supply. Collectors of the first and second transistors are separately connected to the first and second output ends.

Abstract: A drive circuit of a computer system is for driving a mode indicator. The computer system includes a first port and a second port. The mode indicator includes a first receiving end and a second receiving end. The drive circuit includes a first input end connected to the first port, a second input end connected to the second port, a first output end connected to the first receiving end, a second output end connected to the second receiving end. A power supply is connected to the first input end and the second input end via a first resistor and a second resistor respectively. The mode indicator is dichromatic and has two LEDs emitting non-matching colored light.

Abstract: A linearly regulated power supply is provided for providing a load voltage to a load. In a preferred embodiment, the linearly regulated power supply includes: a voltage divider module for receiving a backup voltage and then providing a voltage reference; a controlling module for receiving the voltage reference and then providing a controlling voltage; and a regulating module receiving the controlling voltage and then regulating a core voltage down to a load voltage, the regulating module providing the load voltage to a load. The linearly regulated power supply is capable of reducing the power of the transistor, and has a higher efficiency.