Abstract: An LED driving circuit is provided for driving an LED module, comprising a transistor switch and a feedback controller. The transistor switch has a control terminal, a first terminal, and a second terminal. The first terminal is coupled to the LED module and the control terminal receives a control signal for controlling a current passing through the transistor switch. The feedback controller receives a reference voltage and a current detecting signal indicative of the magnitude of the current and generates the control signal accordingly. The feedback controller is connected to a driving power source with level higher than the level of the first terminal of the transistor switch. Hence, the maximum level of an adjustable range of the control signal is higher than the first terminal of the transistor switch.

Abstract: An LED driving circuit is used for dimming by switching between an operating current and a maintaining current or by voltage clamping of a source/drain of MOSFET that is coupled to the LED module. When the LED module is dimmed off, the voltage across the LED module can be kept at a value around a lighting threshold voltage of the LED module that is a minimum voltage for lighting the LED module. Therefore, a voltage difference between the drain and the source of MOSFET coupled to the LED module is smaller than that in the conventional arts. Hence, a withstand voltage of MOSFET can be reduced, and cost of the LED driving circuit as well as the power consumption of MOSFET can be lessened, thereby improving integral efficiency of the circuit.

Abstract: An LED driving circuit and a MOSFET switch module thereof is disclosed, and the MOSFET switch module which is used to control a current of the LED driving circuit. The present invention employs a voltage clamping device to clamp the voltage level of the drain of transistor in the MOSFET switch module when being turned off. Via this way, the requirement for the withstand voltage of the transistor is lowered, and so the cost and power consumption thereof is reduced.

Abstract: The present invention discloses a battery charging controller for achieving a balanced battery charge. The battery charging controller includes a voltage divider, a switch module and a balance circuit. A reference voltage generated by the voltage divide is used to determine which battery unit in a battery module has an insufficient voltage lower than the others, so that the balance circuit controls the switch module to allow a larger current to charge a lower-voltage battery than a higher-voltage battery, so as to result in substantially the same voltage for each fully charged battery of the battery module.

Abstract: A light emitting diode driving circuit comprising: a current control unit, a current detection unit, and a driving control unit. The current control unit connects to the current detection unit and comprises a control end, a first input/output end, and a second input/output end to individually produce an electric potential detection signal. The light emitting diode driving circuit determines whether driving the light emitting diode is unusual or not according to the electric potential detection signals to decide to start a protect mechanism. Furthermore, the present invention can receive any types of dimming signals to adjust the light of the light emitting diode.

Abstract: A controller for a driving circuit of power source comprises a frequency generator, a pulse width modulator, and a driving device. The frequency generator comprises a latch circuit. The frequency generator provides a pulse signal at a first frequency after the controller is started. After the frequency generator receives an indicating signal, the frequency generator changes the frequency of pulse signal from the first frequency to a second frequency and locks the frequency of pulse signal at the second frequency. The pulse width modulator provides a PWM signal according to the pulse signal and a feedback signal which indicates a status of electric power supply of the driving circuit. The driving device controls semiconductor switches according to the PWM signal.

Abstract: A switching system capable of reducing the noise of the output signal is provided. The switching system includes a first switch and a second switch, wherein the first switch conducts a first signal according to a first control signal; the second switch conducts a second signal according to a second control signal. And the voltages of the first control signal and the second control signal are restricted within a voltage interval to reduce the noise produced during the switching of the switches.

Abstract: A voltage-controlled current source and a frequency scanner using the same are provided. The voltage-controlled current source includes an impedance circuit, an amplifier, a transistor, and a current mirror. A first terminal of the impedance circuit is coupled to a common voltage. A first terminal of the amplifier is coupled to a second terminal of the impedance circuit, and a second terminal of the amplifier receives a control voltage. A gate of the transistor is coupled to an output terminal of the amplifier, and a first source/drain of the transistor is coupled to the other terminal of the impedance circuit. The current mirror is coupled to a second drain/source of the transistor, and includes a current output terminal, wherein a current output by the current output terminal is proportional to the current flowing through the transistor.

Abstract: A control circuit for LEDs is adapted for controlling brightness of a plurality of LEDs as light source in an LCD. The control circuit comprises a control pulse generator and a plurality of LED direct current supplies. The control pulse generator is used for receiving a brightness adjusting signal and generating a plurality of brightness control pulse signals having the same frequency but different phases according to the brightness control signals. The work cycle of the brightness control pulse signal varies in a predetermined range according to the brightness control signal. The LED direct current provider is coupled to the control pulse generator to drive the corresponding LED according to the brightness pulse signal.

Abstract: A switching system capable of reducing the noise of the output signal is provided. The switching system includes a first switch and a second switch, wherein the first switch conducts a first signal according to a first control signal; the second switch conducts a second signal according to a second control signal. And the voltages of the first control signal and the second control signal are restricted within a voltage interval to reduce the noise produced during the switching of the switches.

Abstract: A resonant DC/AC inverter includes a DC power source providing a DC voltage, a half-bridge power switch circuit electrically connected to the DC power source being operative to convert the DC voltage to an AC voltage, a resonant tank electrically connected between an output of the half-bridge power switch circuit and an input of a load being operative to boost and filter the AC voltage to generate an AC power voltage supplied to the load, and a controller being operative to detect a magnitude of current in the load and a magnitude of a voltage across the load and to generate pulse waveforms for turning on and off the half-bridge power switch circuit, wherein the controller substantially instantaneously varies a frequency of the pulse waveforms and a duty cycle of the pulse waveforms so as to operate the resonant DC/AC inverter near a neighborhood of a resonant frequency of the resonant tank regardless of a conduction state of the load and improve the efficiency of the inverter regardless of the higher DC volt

Abstract: An apparatus for generating a pulse width modulated (PWM) signal to control a transforming circuit to drive a loading is provided. The apparatus includes an error signal generator, a control circuit and a comparator. The error signal generator includes a first input terminal for receiving a reference voltage, a second input terminal for receiving a feedback signal generated based on an operating state of the loading respectively, and an output terminal for outputting an error status signal. The comparator includes a first input terminal for receiving the error status signal, a second input terminal for receiving a compare signal, and an output terminal for generating the PWM signal. The control circuit determines whether to provide a setting signal coupled to the output terminal of the error signal generator based on at least one control signal.

Abstract: A DC/DC converter for driving a load is provided. The DC/DC converter includes an inductor, a switch, a capacitor and a rectifier element. The switch and the inductor are coupled in series between a first common level and a second common level. The capacitor and the rectifier element are coupled in series between the first and second terminal of the switch or the inductor. The load is coupled between a coupling point of the capacitor and rectifier element and the second common level, wherein the coupling point of the capacitor and rectifier element outputs an output voltage to drive the load. A control terminal of the switch is switched between open circuit state and short circuit state according to a control signal.

Abstract: A driving apparatus used for driving a light source is provided. The driving apparatus includes a signal processing unit, a control unit, and a driving unit. The signal processing unit generates an enabling signal and a dimming signal according to an input signal. The control unit includes an enabling module and a dimming module. The enabling module enables the driving apparatus according to the enabling signal, and the dimming module generates a dimming driving signal according to the dimming signal. The driving unit adjusts the brightness of the light source according to the dimming driving signal.

Abstract: A voltage-controlled current source and a frequency scanner using the same are provided. The voltage-controlled current source includes an impedance circuit, an amplifier, a transistor, and a current mirror. A first terminal of the impedance circuit is coupled to a common voltage. A first terminal of the amplifier is coupled to a second terminal of the impedance circuit, and a second terminal of the amplifier receives a control voltage. A gate of the transistor is coupled to an output terminal of the amplifier, and a first source/drain of the transistor is coupled to the other terminal of the impedance circuit. The current mirror is coupled to a second drain/source of the transistor, and includes a current output terminal, wherein a current output by the current output terminal is proportional to the current flowing through the transistor.

Abstract: A loading system and a controller thereof are disclosed. The controller includes an adjustable triangle wave generator, an error signal generator, and a pulse signal generator. The triangle-wave generator is adapted to perform an amplitude and frequency operation according to the reference voltage and the feedback voltage for generating an amplitude-frequency adjustable triangle wave according to a variation of the feedback voltage. The error signal generator is adapted to perform an error operation according to the feedback voltage and the reference voltage for outputting an error signal. The pulse signal generator is adapted to receive and compare the error signal and the amplitude-frequency adjustable triangle wave for outputting a pulse controlling signal for the loading system.

Abstract: A variable gain device having higher linearity and wider gain range is provided. The variable gain device includes a transduction unit for generating an output current, a control unit for adjusting the current gain of the gain amplifying unit according to a gain control signal, a gain amplifying unit receiving the current signal and generating a gain adjustable current according to the current gain of the control unit, an output DC level control unit controlling the DC level of the output signal of the variable gain device, and an output unit generating an output signal according to the signals output by the output DC level control unit and the gain amplifying unit.

Abstract: A DC/DC converter comprises a switch device, an inductor, a rectifying device and a capacitor. Switch device has a first terminal coupled to a DC power supply and a control terminal receiving a control signal. Inductor has a first terminal electrically coupled to a second terminal of switch device. Rectifying device has a first terminal electrically coupled to the first terminal of inductor. Capacitor has a first terminal electrically coupled to a second terminal of rectifying device, a second terminal electrically coupled to a second terminal of inductor. Switch device is switched between a first and second states based on control signals, the power of DC power supply is stored into inductor when switch device is in the first state; the power stored in inductor is released and provided to capacitor and LED module through rectifying device when switch device is in the second state.

Abstract: A driving circuit for a plurality of light-emitting diodes (LEDs) comprises a transformer, a driving module, and a protection module. The transformer has a primary coil and a secondary coil, wherein a first end of the primary coil is coupled to a voltage source. Furthermore, a second end of the primary coil of the transformer is coupled to the driving module. The driving module determines whether to deliver electrical power to the transformer according to a pulse-width modulation (PWM) signal and an error signal. The protection module is coupled to the secondary coil. When a driving voltage output by the transformer to the LEDs is less than a first preset voltage or greater than a second preset voltage, the protection module generates the error signal to the driving module.

Abstract: The invention provides an LED current balancing circuit, comprising a first and a second LED set coupled to a voltage source, a first transistor, and a second transistor. The first LED set comprises a first loader. The first transistor and the second transistor form a current balancing circuit for adjusting currents passing through the first and second LED sets.