Patent ID: 8471497

Claim:
A control circuit for a LED driver having a feedback circuit detecting an output current of the LED driver to generate a feedback voltage, the control circuit comprising: a reference voltage adjuster connected to a power input terminal of the LED driver, detecting an input voltage of the LED driver and adjusting a first reference voltage accordingly, to thereby generate a second reference voltage; and an error amplifier connected to the feedback circuit and the reference voltage adjuster, generating an error signal according to a difference between the feedback voltage and the second reference voltage, for controlling the output current; wherein the reference voltage adjuster comprises: a first resistor configured to determine a first current according to a difference between the input voltage and a third reference voltage; an operational circuit operating with the first current and a reference current to generate a second current; and a second resistor connected to the operational circuit, configured to generate an adjust voltage according to the second current; wherein the second reference voltage is derived by subtracting the adjust voltage from the first reference voltage.