O2 Micro, Incorporated

02micro Inc.

Tiesheng Yan

Ching-Chuan Kuo

Feng Lin

Zhimou Ren

Jun Ren

Youling Li

Xinhe Su

Yunning Xie

Yung Lin Lin

Jianping Xu

Ying-Chieh Su

Ching Chuan Kuo

Jianlong Gao

A circuit for driving a light source includes a power converter coupled between a power source and the light source, and a controller coupled to the power converter. The power converter receives power from the power source and provides a regulated power to the light source. The controller receives a conduction status signal indicating a conduction state of a dimmer coupled between the power source and the power converter, and adjusts the brightness of the light source based on the conduction status signal. The controller also receives an operation indicating signal indicative of operation of an ON/OFF switch coupled to the dimmer, and adjusts color temperature of the light source based on the operation indicating signal.

Controlling brightness and color temperature of light sources

A circuit includes a bridge circuit, a converter, and a controller. The bridge circuit receives power from first and second power lines of a switch and generates a rectified voltage. The switch is capable of operating in a first state in which the switch conducts power to the first power line but not the second power line, a second state in which the switch conducts power to the second power line but not the first power line, and a third state in which the switch conducts power to both the first and second power lines. The converter converts the rectified voltage to an output voltage to drive a light source, and controls a current through the light source according to a driving signal. The controller monitors the operation state of the switch and generates the driving signal based on the operation state to control brightness/dimming of the light source.

Circuits and methods for driving a light source

A flyback converter includes a transformer and a controller operable for controlling a switch coupled in series with a primary winding of the transformer. The controller is configured to operate in multiple modes including a burst mode and a standby mode. In the burst mode, the controller generates a first plurality of discrete pulse groups to turn on the switch and a duration of each pulse in the first plurality of discrete pulse groups is determined by a first reference signal having a first predetermined voltage. In the standby mode, the controller generates a second plurality of discrete pulse groups to turn on the switch and a duration of each pulse in the second plurality of discrete pulse groups is determined by a second reference signal having a second predetermined voltage which is greater than the first predetermined voltage of the first reference signal.

Flyback converter and method for controlling a flyback converter

A driving circuit for controlling power of a light-emitting diode (LED) light source includes a transformer, a switch controller, and a dimming controller. The transformer has a primary winding that receives input power from an AC/DC converter and a secondary winding that provides output power to the LED light source. The switch controller coupled between an optical coupler and the primary winding receives a feedback signal indicative of a target level of a current flowing through the LED light source from the optical coupler, and controls input power to the primary winding according to the feedback signal. The dimming controller coupled to the secondary winding receives a switch monitoring signal indicative of an operation of a power switch coupled between an AC power source and the AC/DC converter, and regulates the output power by adjusting the feedback signal according to the switch monitoring signal.

Circuits and methods for driving LED light sources

A controller for controlling power to a light source includes a first sensing pin, a second sensing pin, and a driving pin. The first sensing pin receives a first signal indicating an instant current through an energy storage element. The second sensing pin receives a second signal indicating whether the instant current decreases to a predetermined level. The driving pin provides a driving signal to a switch to control a current through the light source to a target level. The driving signal is generated based on one or more signals selected from the first signal and the second signal. The controller further includes an error amplifier for generating an error signal based on the first signal and a reference signal indicating the target level. The output of the error amplifier is coupled to a capacitor.

Circuits and methods for driving light sources

A circuit for driving a light-emitting diode (LED) light source includes a converter, a saw-tooth signal generator, and a controller. The converter includes a switch which is controlled by a driving signal. The converter provides a sense signal indicating the current through said LED light source. The saw-tooth signal generator generates a saw-tooth signal based on the driving signal. The controller generates the driving signal based on signals including the saw-tooth signal and the first sense signal to adjust the current through the LED light source to a target level and to correct a power factor of the driving circuit by controlling an average current of the input current to be substantially in phase with said input voltage.

A controller for controlling power to a light source includes a first sensing pin, a second sensing pin, a third sensing pin, and a driving pin. The first sensing pin receives a first signal indicating an instant current flowing through an energy storage element. The second sensing pin receives a second signal indicating an average current flowing through the energy storage element. The third sensing pin receives a third signal indicating whether the instant current decreases to a predetermined current level. The driving pin provides a driving signal to a switch to control an average current flowing through the light source to a target current level. The driving signal is generated based on one or more signals selected from the first signal, the second signal and the third signal.

Embodiments of the invention provided a driving circuit for powering a light-emitting diode (LED) light source. The driving circuit includes a rectifier, a filter capacitor, and a control circuit. The rectifier converts an AC voltage from an AC power source to a rectified AC voltage. The filter capacitor coupled to the rectifier filters the rectified AC voltage to provide a DC voltage. The control circuit controls power supplied to the LED light source. The control circuit enables a discharging current periodically to discharge the filter capacitor if a switch coupled between an AC power source and a rectifier is turned off and disables the discharging current if the control circuit determines that the switch is turned on.

Driving circuit for powering LED light sources

An AC-to-DC converter for converting an AC voltage to a DC voltage includes a first converter, a second converter, a sense circuit, a controller, and an enabling circuit. The first converter converts an AC voltage to a first DC voltage. The second converter converts the first DC voltage to a second DC voltage. The sense circuit coupled to the first and second converters provides a first sense signal indicative of the first DC voltage and a second sense signal indicative of the AC voltage. The controller coupled to the first and second converters controls the first and second DC voltages. The enabling circuit coupled to the sense circuit generates a control signal to the controller to disable both the first converter and the second converter by comparing the first sense signal to a first threshold voltage and comparing the second sense signal to a second threshold voltage.

Circuits and methods for alternating current-to-direct current conversion

A driving circuit includes a first inductor coupled in series with a light source for providing power to the light source. A controller coupled to the first inductor can control a switch coupled to the first inductor, thereby controlling a current flowing through the first inductor. A current sensor coupled to the first inductor can provide a first signal indicative of the current flowing through the first inductor, regardless of whether the switch is on or off. The switch is controlled according to the first signal. A second inductor magnetically coupled to the first inductor is also electrically coupled to the first inductor via a common node between the switch and the first inductor for providing a reference ground for the controller. The reference ground is different from the ground of the driving circuit.

A controller for controlling dimming of a light-emitting diode (LED) light source provides a pulse signal by comparing a sensing signal indicative of a current flowing through the LED light source to a reference signal. The controller controls the current through the LED light source according to the pulse signal during a first state of a pulse-width modulation signal and cutting off the current through the LED light source during a second state of the pulse-width modulation signal. The controller receives a dimming request signal indicative of an operation of a power switch coupled between an AC power source and a bridge rectifier and adjusts both a level of the reference signal and a duty cycle of the pulse-width modulation signal based on the dimming request signal.

A driving circuit for driving a light source includes a power converter, a controller and a voltage-controlled current source. The power converter is coupled to the light source, and receives an input voltage from a power source and provides an output voltage to the light source. The power converter includes a switch coupled in series with the light source. The controller is coupled to the power converter and controls a power of the light source by controlling the switch. The voltage-controlled current source is coupled to the controller and provides a first current. The controller controls the switch based on the first current.

Circuits and methods for controlling power of light sources

A power supply system includes a power converter, a switch, and a controller. The power converter is operable for providing power to a load. The switch is coupled to the power converter and is operable for adjusting the power to the load. The switch has a gate, a source and a drain. The controller is coupled to the switch and is operable for controlling a state of the switch. The controller has a first control terminal for providing a gate voltage to the gate of the switch, a second control terminal for providing a source voltage to the source of the switch, and an input terminal for receiving a supply voltage via the source of the switch. The controller is also operable for limiting the supply voltage within a predetermined maximum level by regulating the gate voltage to a preset level.

Power supply systems with controllable power

A circuit for driving a light source, e.g., an LED light source, includes a converter, a sensor, and a controller. The converter converts an input voltage to an output voltage across the LED light source based upon a driving signal. A duty cycle of the driving signal determines an average current flowing through the LED light source. The sensor is selectively coupled to and decoupled from the converter based upon the driving signal. The sensor generates a sense voltage indicative of a current flowing through the LED light source when the sensor is coupled to the converter. The controller is coupled to the converter and sensor. The controller compares the sense voltage to a reference voltage indicative of a predetermined average current through the LED light source to generate a compensation signal and generates the driving signal based upon the compensation signal. The duty cycle of the driving signal is adjusted based upon the compensation signal to adjust the average current flowing through the LED light source to the predetermined average current.

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Chengdu, China

Tiesheng Yan