Abstract:
A power conversion driving circuit is provided. The power conversion drive circuit includes a converting circuit, a control circuit and a load circuit. The converting circuit is coupled to an input voltage. The control circuit is coupled to the converting circuit for controlling the converting circuit to convert the input voltage to an output voltage. The load circuit includes a load detecting unit and a load. The load is coupled to the output voltage, and the load detecting unit is coupled to a detecting voltage source. The load detecting unit generates a load detecting signal to re-start the control circuit when the load circuit is inserted into the power conversion driving circuit.
Abstract:
The present invention provides an LED driving circuit with temperature compensation, comprising a power transforming circuit, an LED module and a controller. The transforming circuit receives an electrical power from an input power source and transforms it into an output voltage according to a control signal. The LED module is coupled to the transforming circuit. The controller generates the control signal according to an operation temperature and a voltage feedback signal indicative of the output voltage, and makes the output voltage decrease with increasing operation temperature. Therefore, the LED driving circuit of the present invention has an effect of temperature compensation that compensates the influence of the decreased driving voltage of the LED module due to temperature.
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:
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 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:
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 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:
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 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 converting controller comprises a power pin, a ground pin, at least one input pin, at least one output pin, at least one set pin and a failure generating circuit. The power pin is adapted to be coupled with a power source to receive electric power for operation, and the ground pin is adapted to be grounded. The input pin is adapted to receive a corresponding input signal and the output pin is used to output a corresponding output signal. The set pin is adapted to set a corresponding operating parameter of the converting controller. The failure generating circuit is coupled with and uses one of the input pin and the set pin as a protection output pin. The failure generating circuit modulates the level of the protection output pin to be a protection logic level when the converting controller is under a protection state.