Described herein are systems and methods for generating short load current pulses using an H-bridge. In various embodiments, this is accomplished by controlling, in a shunting mode, a low-side switch of the H-bridge to drive a first average current and controlling, in a non-shunting mode, a high-side switch of the H-bridge to drive a second average current such that the first and second average currents are substantially the same and reduce a current pulse width of the load current.

A dimmable ballast circuit for a compact fluorescent lamp controls the intensity of a lamp tube in response to a phase-control voltage received from a dimmer switch. The ballast circuit comprises a phase-control-to-DC converter circuit that receives the phase-control voltage, which is characterized by a duty cycle defining a target intensity of the lamp tube, and generates a DC voltage representative of the duty cycle of the phase-control voltage. Changes in the duty cycle of the phase-control voltage that are below a threshold amount are filtered out by the converter circuit, while intentional changes in the duty cycle of the phase-control voltage are reflected in changes in the target intensity level and thereby the intensity level of the lamp tube.

A dimmable ballast circuit for a compact fluorescent lamp controls the intensity of a lamp tube in response to a phase-control voltage received from a dimmer switch. The ballast circuit comprises a phase-control-to-DC converter circuit that receives the phase-control voltage, which is characterized by a duty cycle defining a target intensity of the lamp tube, and generates a DC voltage representative of the duty cycle of the phase-control voltage. Changes in the duty cycle of the phase-control voltage that are below a threshold amount are filtered out by the converter circuit, while intentional changes in the duty cycle of the phase-control voltage are reflected in changes in the target intensity level and thereby the intensity level of the lamp tube.

An emergency output circuit for starting LED lamp tubes with leakage protection comprises a PWM pulse generator provided with a PWM chip. When a control terminal detects a power outage, a high level is instantly output to the PWM chip, and the PWM pulse generator outputs complementary drive PWM rectangular waves with a controllable dead time, which are boosted and filtered into a 250V DC voltage; then, positive and negative alternating square waves are formed through a full-bridge inverter circuit, and two pairs of MOS transistors are turned on alternately through complementary PWM control to generate an AC voltage UAB on an LED lamp tube; and finally, an AC rectangular wave slowly changing into a stable 135V AC output from a 250V DC output is obtained through a correction circuit to replace existing methods to turn on the LED tube, thus effectively simplifying the circuit.

An emergency output circuit for starting LED lamp tubes with leakage protection comprises a PWM pulse generator provided with a PWM chip. When a control terminal detects a power outage, a high level is instantly output to the PWM chip, and the PWM pulse generator outputs complementary drive PWM rectangular waves with a controllable dead time, which are boosted and filtered into a 250V DC voltage; then, positive and negative alternating square waves are formed through a full-bridge inverter circuit, and two pairs of MOS transistors are turned on alternately through complementary PWM control to generate an AC voltage UAB on an LED lamp tube; and finally, an AC rectangular wave slowly changing into a stable 135V AC output from a 250V DC output is obtained through a correction circuit to replace existing methods to turn on the LED tube, thus effectively simplifying the circuit.

A variable light distribution light source includes an array-type light-emitting device. The array-type light-emitting device includes a power supply terminal and multiple pixel circuits electrically coupled and spatially arranged in a matrix. A power supply circuit includes a power supply unit that supplies electric power to the array-type light-emitting device. An output of a DC/DC converter is coupled to the power supply terminal VDD of the array-type light-emitting device via an output terminal. A voltage setting circuit generates a controllable correction voltage. A feedback circuit generates a feedback voltage based on the correction voltage and the control target voltage that corresponds to the output voltage of the DC/DC converter, and supplies the feedback voltage to a feedback pin of a converter controller.

A single channel-based multi-functional light emitting diode lamp driving system includes: first and second light source groups distinguished for each lamp function thereof; a single LED lamp driving module adjusting an input voltage to a voltage required for each lamp function and to apply it to the first and second light source groups; a switching module controlling on or off of the first and second light source groups; and a control module controlling light amounts of the first and second light source groups by performing time-division control on an on or off time of the switching module in conjunction with the LED lamp driving module, wherein the control module is configured to perform time division turn-on control on the first and second light source groups by controlling at least one of a current value applied to the first and second light source groups or a duty ratio thereof in a high-beam passing mode.

In various embodiments, a switched-mode power supply is provided. The switched-mode power supply includes at least two output stages. Each output stage has a converter. A frequency of at least one of the output stages is modulated by way of a modulation unit configured to provide a modulation signal that is combined with a switching signal for driving a switching element of the converter of the at least one output stage.

An the LED driving circuit, for driving an the LED load, includes: a bridge rectifier for rectifying an AC input voltage into a DC voltage; a serial capacitor voltage divider coupled to the bridge rectifier, including a plurality of serial capacitors; a half-bridge switch, coupled to the serial capacitor voltage divider; and a controller coupled to the half-bridge switch, for determining whether the DC voltage is higher than a threshold value and for controlling the half-bridge switch in a full-voltage mode or a half-voltage mode. In the full-voltage mode, the plurality of serial capacitors of the serial capacitor voltage divider synchronously supply power to the LED load. In the half-voltage mode, the plurality of serial capacitors of the serial capacitor voltage divider alternatively supply power to the LED load.

A display device is provided. The display device of the disclosure includes a light emitting unit, a current source, a voltage comparator, and an emission control unit. The current source is configured to output a supply current. The voltage comparator is configured to receive a voltage data and a ramp signal. The emission control unit receives an emission enable signal, and coupled to the light emitting unit, the current source, and the voltage comparator. The voltage comparator outputs a comparison signal to the emission control unit according to the voltage data and the ramp signal. The emission control unit outputs a driving current to the light emitting unit according to the supply current, the emission enable signal, and the comparison signal.