Vimicro Corporation

Wuxi Vimicro Corporation

Wenbo Tian

Hang Yin

Zhao Wang

Wang Zhao

Techniques pertaining to a voltage regulator with a current limiting circuit having low quiescent current are disclosed. According to one aspect of the present invention, a current limiting circuit is provided for limiting a current passing through an output pass circuit of a voltage regulator, the current limiting circuit comprises: a current sampling circuit for sampling the current passing through the output pass circuit to obtain a duplicated current being proportional to the current passing through the output pass circuit; a current mirror circuit for producing a mirror current being proportional to the duplicated current with the duplicated current as a reference current; a current to voltage converter for producing a voltage being proportional to the mirror current; and a voltage comparator for comparing the voltage produced by the current to voltage converter with a threshold voltage and turning off the output pass circuit when the voltage produced by the current to voltage converter is larger than or equal to the threshold voltage.

Current limiting circuit and voltage regulator using the same

Techniques pertaining to driving LEDs on multiple branches of a circuit are disclosed. According to one aspect of the present invention, an LED drive circuit includes a boost circuit configured for receiving an input voltage and providing an output voltage according to a control signal, a selector configured for alternatively selecting one of the feedback signals as an output feedback signal and switching on a corresponding branch circuit, and a pulse-width modulation (PWM) controller configured for generating a pulse-width modulation signal as the control signal for the boost circuit according to the output feedback signal of the selector, essentially to match respective currents in the multiple branches.

Driver and method for driving LEDS on multiple branch circuits

A scan mode is used in a voltage detection circuit. An oscillator in the circuit is always on and a system including the voltage detection circuit detects various abnormal conditions, such as overcharging, overdischarging and overcurrent one by one for some clocks. To reduce the power consumption, the voltage detection circuit is turned on only once for several clocks. The on-time is very short and lasts about only one tenth of a clock cycle time. In other times, the voltage detection circuit is turned off to save power consumption.

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Beijing, China

Wenbo Tian