Abstract:
A driving circuit for driving a light source includes a converter and a dimming controller. The converter coupled to a power source is operable for receiving power from the power source and for providing regulated power to the light source according to control signals. The dimming controller coupled to the converter is operable for monitoring a power switch coupled between the power source and the converter, for receiving a color change signal indicating a first set of operations of the power switch and a dimming request signal indicating a second set of operations of the power switch, for controlling the control signals to change the color of the light source in response to the color change signal, and for controlling the control signals to adjust the brightness of the light source in response to the dimming request signal.
Abstract:
A controller for controlling dimming of a light source includes a detection pin, an input signal pin, and a monitoring pin. The detection pin is operable for monitoring a rectified voltage and for detecting whether the rectified voltage comes from a TRIAC dimmer or an on/off switch dimmer. The input signal pin is operable for receiving an input signal indicative of the rectified voltage and the controller controls dimming of the light source according to the input signal if the rectified voltage comes from a TRIAC dimmer. The monitoring pin is operable for receiving a monitoring signal indicating an operation of the on/off switch dimmer and the controller controls dimming of the light source according to the monitoring signal if the rectified voltage comes from an on/off switch dimmer.
Abstract:
A circuit for driving a light source includes a voltage converter, a switch and a controller. The voltage converter converts an AC input voltage signal to a first rectified AC voltage signal. The voltage converter further generates an average signal proportional to an average voltage level of the first rectified AC voltage signal. The switch is coupled to the light source in series. The controller coupled to the voltage converter and the switch compares the first rectified AC voltage signal with the average signal to generate a pulse signal. The controller further generates a dimming control signal based on the pulse signal to control the switch thereby controlling dimming of the light source.
Abstract:
A DC/AC cold cathode fluorescent lamp (CCFL) inverter circuit includes a transformer with a primary winding and a secondary winding for providing increased voltage to a CCFL, a first and second MOSFET switches for selectively allowing direct current of a first polarity and a second polarity to flow through the transformer respectively. The primary and secondary windings of the transformer are electrically coupled to ground. A capacitor divider is electrically coupled to the CCFL for providing a first voltage signal representing a voltage across the CCFL. A first feedback signal line receives the first voltage signal. A timer circuit is coupled to the first feedback signal line for providing a time-out sequence of a predetermined duration when the first voltage signal exceeds a predetermined threshold. A protection circuit shuts down the first switch and the second switch when the first voltage signal exceeds the predetermined threshold after the predetermined duration.
Abstract:
A controller for controlling dimming of a light-emitting diode (LED) light source includes a switch monitoring pin, a current monitoring pin, and a control pin. The switch monitoring pin monitors an operation of a power switch which transfers an AC voltage to a rectifier when the power switch is on. The current monitoring pin receives a current monitoring signal indicating a current flowing through the LED light source. The control pin generates a control signal to control a second switch coupled in series with the LED light source to adjust the brightness of the LED light source according to the operation of the power switch.
Abstract:
Embodiments in accordance with the present invention provide circuits and methods for driving light sources, e.g., a light-emitting diode (LED) light source. In one embodiment, a printed circuit board (PCB) includes a bridge rectifier rectifying an AC voltage to a rectified AC voltage, an LED light source, and a first switch coupled to the LED light source in series controlling a current through the LED light source according to a predetermined current reference. The LED light source and the first switch coupled in series receive the rectified AC voltage while the first switch is controlled linearly.
Abstract:
A controller for controlling dimming of an LED light source includes a control terminal and dimming control circuitry coupled to the control terminal. The control terminal provides a driving signal to control a control switch coupled to the LED light source, thereby controlling the dimming of the LED light source. The dimming control circuitry generates the driving signal according to a set of operations of a power switch that transfers an AC signal. The dimming control circuitry further adjusts the driving signal by counting multiple waves of the AC signal to control the dimming of the LED light source.
Abstract:
In one embodiment, a driving circuit includes an AC/DC converter which converts an AC voltage to a DC voltage and a DC/DC linear regulator which regulates a current through, e.g., an LED light source, according to a first current reference if a monitoring signal indicating the DC voltage is within a predetermined range, and regulates the current according to a second current reference less than the first current reference if the monitoring signal is beyond the predetermined range. In another embodiment, a controller controlling power to an LED light source turns on a first plurality of LEDs and turns off a second plurality of LEDs if a monitoring signal indicative of a DC voltage received by the LED light source is within a predetermined range, and turns on both first and second plurality of LEDs if the monitoring signal is beyond the predetermined range.
Abstract:
A portable lighting device includes a power source, a controller, and a load. The controller comprises a power input terminal which is electrically connected to the power source via a switch. The load is electrically connected to a power output terminal of the controller and is capable of providing a feedback signal. The controller regulates the power being provided to the load according to the feedback signal and a conduction status of the switch.
Abstract:
A driving circuit for controlling power of a light source includes a power converter coupled to a power source and the light source, and a dimming controller coupled to the power converter. The power converter can receive power from the power source and provide a regulated power to the light source. The power converter includes a control switch coupled in series with the light source. The dimming controller can monitor a power switch coupled between the power source and the driving circuit, and receive a dimming request signal and a dimming termination signal. The dimming request signal can indicate a first set of operations of the power switch. The dimming termination signal can indicate a second set of operations of the power switch. The dimming controller can continuously adjust the regulated power from the power converter by controlling the control switch if the dimming request signal is received, and can stop adjusting the regulated power from the power converter if the dimming termination signal is received.