Abstract: A PWM controller capable of controlling output current ripple via a resistor, and an LED driver circuit using the PWM controller, the PWM controller including: a sawtooth signal generation unit for generating a sawtooth signal, of which a slope of a positive ramp is controlled by a control current, and the control current is determined by an external resistor; an amplifier having a positive input end coupled with a reference voltage, a negative input end coupled with a current sense signal, and an output end coupled with an external capacitor for generating a comparison signal; and a comparator having a positive input end coupled with the sawtooth signal, a negative input end coupled with the comparison signal, and an output end for generating an end-of-conduction signal, wherein the end-of-conduction signal will become active whenever the sawtooth signal reaches the comparison signal.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a control voltage generator, used to generate a control voltage according to a switching count of a power line; an oscillator, used to generate an oscillating signal, wherein the oscillating signal is of a fixed frequency and has a rising voltage portion and a falling voltage portion; and a comparator, used to generate a high side gating signal according to voltage comparison of the oscillating signal and the control voltage.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a line switching sensing circuit, used to generate a switching sensing signal by performing a voltage comparison operation on a DC voltage; an oscillating signal gating unit, used to gate an oscillating signal with a pulse signal to generate a gated oscillating signal, wherein the pulse width of the pulse signal is generated according to the switching sensing signal; and a non-overlapping driver, used to generate a high side driving signal and a low side driving signal according to the gated oscillating signal.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a line switching sensing circuit, used to generate a switching sensing signal by performing a voltage comparison operation on a DC voltage, and generate a reset signal according to the off time of the power line; a control voltage generator, used to generate a control voltage according to the count of said switching sensing signal; a voltage controlled oscillator, used to generate an oscillating signal according to the control voltage; and a non-overlapping driver, used to generate a high side driving signal and a low side driving signal according to the oscillating signal.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a line switching sensing circuit, used to generate a switching sensing signal by performing a voltage comparison operation on a DC voltage, and generate a reset signal according to the off time of the power line; a dimming voltage generator, used to generate a dimming voltage according to a count of the switching sensing signal; and a phase-controlled non-overlapping driver, used to generate a high side driving signal and a low side driving signal for delivering a lamp current according to the dimming voltage, wherein the dimming voltage is used to generate a phase, and the phase is used to generate the lamp current.

Abstract: The present invention relates a single chip ballast controller for step-dimming of a fluorescent lamp, comprising: a counting circuit, used to generate a switching count by counting the instances where the supply voltage falls below a threshold voltage; a reference voltage generator, used to generate a reference voltage proportional to the switching count; and a gating signal generator, used to generate a high side driving signal and a low side driving signal according to an error voltage between the reference voltage and a current sensing voltage to regulate the current sensing voltage at the reference voltage, wherein the current sensing voltage is proportional to a lamp current flowing through the fluorescent lamp.

Abstract: A power source control method for a multi-module light-emitting diode (LED) circuit includes detecting a signal characteristics value according to a plurality of switching signals, being used for controlling the conduction of currents in the plurality of lighting modules, comparing the signal characteristics value with a pre-determined value to generate a comparing result, and outputting the comparing result to an external power supply device, such that the external power supply device can adjust the voltage level of an input voltage of the multi-module LED circuit according to the comparing result.

Abstract: A driving device for an LED circuit includes a power receiving terminal, a capacitor, and a light adjusting unit. The power receiving terminal is coupled to a switch for receiving a DC power source that supplies for the LED circuit and the driving device via the switch. The capacitor is coupled to the power receiving terminal, and is utilized for storing energy. The light adjusting unit is coupled to the power receiving terminal and the capacitor, and is utilized for generating a control signal according the status of the switch when a voltage on the capacitor decreases and does not decrease below a first threshold voltage, for adjusting light intensity of the LED circuit.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a control voltage generator, used to generate a control voltage according to a switching count of a power line; an oscillator, used to generate an oscillating signal, wherein the oscillating signal is of a fixed frequency and has a rising voltage portion and a falling voltage portion; and a comparator, used to generate a high side gating signal according to voltage comparison of the oscillating signal and the control voltage.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a line switching sensing circuit, used to generate a switching sensing signal by performing a voltage comparison operation on a DC voltage, and generate a reset signal according to the off time of the power line; a control voltage generator, used to generate a control voltage according to the count of said switching sensing signal; a voltage controlled oscillator, used to generate an oscillating signal according to the control voltage; and a non-overlapping driver, used to generate a high side driving signal and a low side driving signal according to the oscillating signal.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a line switching sensing circuit, used to generate a switching sensing signal by performing a voltage comparison operation on a DC voltage, and generate a reset signal according to the off time of the power line; a dimming voltage generator, used to generate a dimming voltage according to a count of the switching sensing signal; and a phase-controlled non-overlapping driver, used to generate a high side driving signal and a low side driving signal for delivering a lamp current according to the dimming voltage, wherein the dimming voltage is used to generate a phase, and the phase is used to generate the lamp current.

Abstract: The present invention discloses an electronic ballast with dimming control from power line sensing for a fluorescent lamp, comprising: a line switching sensing circuit, used to generate a switching sensing signal by performing a voltage comparison operation on a DC voltage; an oscillating signal gating unit, used to gate an oscillating signal with a pulse signal to generate a gated oscillating signal, wherein the pulse width of the pulse signal is generated according to the switching sensing signal; and a non-overlapping driver, used to generate a high side driving signal and a low side driving signal according to the gated oscillating signal.

Abstract: A direct current (DC) drive includes a voltage input unit, a comparing unit, a latch unit and a voltage output unit. The voltage input unit has at least one input terminal and at least one output terminal provides a DC voltage. The comparing unit receives the DC voltage and generates a comparison control signal according to a comparison result obtained by comparing a voltage of a positive voltage terminal with a voltage of a negative voltage terminal. The latch unit is connected to the comparing unit and the voltage input unit. The voltage output unit connected to the latch unit receives the DC voltage from the voltage input unit. The latch unit selectively provides the DC voltage to the voltage output unit according to the comparison control signal.

Abstract: The present invention provides a DC to DC conversion circuit, comprising a DC power supply, a DC to DC converter, a power management IC and a load, wherein the load may be a backlight source of a liquid crystal display. The power management IC controls the DC to DC converter to convert a DC voltage supplied by the DC power supply to an output voltage of the DC to DC converter, which is supplied to the load. The power management IC is capable of controlling the DC to DC converter to adjust the output voltage to a minimum voltage actually needed by the load according to the variation of the minimum voltage which is actually needed by the load.

Abstract: The present invention provides a DC to DC conversion circuit, comprising a DC power supply, a DC to DC converter, a power management IC and a load, wherein the load may be a backlight source of a liquid crystal display. The power management IC controls the DC to DC converter to convert a DC voltage supplied by the DC power supply to an output voltage of the DC to DC converter, which is supplied to the load. The power management IC is capable of controlling the DC to DC converter to adjust the output voltage to a minimum voltage actually needed by the load according to the variation of the minimum voltage which is actually needed by the load.

Abstract: A backlight module of a display panel includes a first light source, a second light source, a first inverter, and a second inverter. The first light source is disposed on a first side of the display panel and includes a first light-emitting device and a second light-emitting device. The second light source is disposed on a second side of the display panel and includes a third light-emitting device and a fourth light-emitting device. The first inverter is coupled to the first and third light-emitting devices, and the second inverter is coupled to the second and fourth light-emitting devices.