Patent ID: 8148911

Claim:
A current balance circuit, comprising: a reference current source unit, to provide stable current; a current balance unit, connected to a plurality of light units, allows current between said plurality of light units to remain stable, independent from input voltage of said plurality of light units; a boost unit, connected to said plurality of light units to convert input voltage and supply voltage to said plurality of light units; a dimming control unit, connected to said reference current source unit and said current balance unit, controls operation of said current balance unit; a control unit, connected to said dimming control unit, transmits pulse width modulation (PWM) signal to control operation for said plurality of light units; and a detection unit, connected to said plurality of light units and said current balance unit, to detect minimum operating voltage for said plurality of light units; wherein said detection unit includes, a comparator; a plurality of open loop detection circuits, each connected to a plurality of inputs of said comparator; and an analog selector, connected to output of said comparator, for selection of input signal.