O2 Micro, Incorporated

Xinhe Su

Ching-Chuan Kuo

Tiesheng Yan

Chun Lu

Youling Li

Feng Lin

Yung Lin Lin

Luyang Luo

Stefan Maireanu

Ching Chuan Kuo

Jianping Xu

Xiaodong Wang

Feng Shi

Alex Hartular

Juan Zhao

Xiang Geng

A method for powering a load by a light source driving circuit is disclosed. The method includes: acquiring a first sensing signal indicative of an average current flowing through the load; generating a first temperature detecting signal indicative of an ambient temperature of the light source driving circuit; and adjusting the average current flowing through the load based on the first temperature detecting signal and the first sensing signal to make the average current flowing through the load to be inversely proportional to the ambient temperature of the light source driving circuit if the ambient temperature of the light source driving circuit is between a first temperature threshold and a second temperature threshold.

Driving circuits and methods for controlling light source

A circuit for powering a LED light source includes a converter and a controller. The converter provides an output voltage, and includes a first switch which is turned on and off alternately according to a driving signal to control a current. The controller generates the driving signal which is a periodic signal having a first state and a second state per time period. The first switch is turned on when the driving signal operates in the first state, and is turned off when the driving signal operates in the second state. The controller modulates a time period of the driving signal and a time duration of the first state, such that a quotient of the time duration squared and the time period is substantially independent of a change of the time period, and the current is substantially independent of the change.

Circuits and methods for driving 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.

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.

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 current control system includes a first switch, a second switch, and a controller. The second switch is coupled in parallel with the first switch and operable for providing a feedback signal indicative of a current flowing through the first switch. The feedback signal is determined by a width-to-length ratio of the first switch and a width-to-length ratio of the second switch. In addition, the controller is coupled to the first and second switches and operable for adjusting the current according to the feedback signal.

Current control systems with current feedbacks

A power supply system can include a primary power supply coupled to an output, and a secondary power supply coupled to the output. The primary power supply provides power to the output when a voltage level of the secondary power supply is less than a first predetermined level. The secondary power supply provides power to the output when the voltage level of the secondary power supply is greater than the first predetermined level. The secondary power supply not only provides power to the output, but also charges the primary power supply when the voltage level of the secondary power supply is greater than a second predetermined level that is greater than the first predetermined level.

Power supply topology

A power management system includes a power management unit (PMU) and a current sensor. The PMU is operable for controlling a first power source and a second power source. The second power source is operable for being charged by the first power source via a charging path. The current sensor has a first terminal coupled to the first power source and the second power source and has a second terminal coupled to the second power source via the charging path. The current sensor is operable for sensing a first current flowing from the first power source through the current sensor and for sensing a second current flowing from the second power source through the current sensor.

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Chengdu, China

Xinhe Su