Patent ID: 8400072

Claim:
A light emitting device driver circuit, comprising: a primary side circuit for receiving AC power and generating a primary voltage; a transformer coupled to the primary side circuit, the transformer including a primary winding and a secondary winding, for converting the primary voltage to a secondary voltage; and a secondary side circuit coupled to the transformer, the secondary side circuit generating an output voltage according to the secondary voltage, and providing an output current to a light emitting device circuit; wherein the secondary winding has a first winding and a second winding, and the first and second windings provide a positive voltage and a negative voltage respectively, the positive and negative voltages together forming the secondary voltage, wherein the output voltage includes a positive output voltage and a negative output voltage, and the light emitting device circuit is coupled between the positive and negative output voltages, and wherein the secondary side circuit includes an operational amplifier which generates an operation signal according to a current detection signal related to the output current; and wherein the driver circuit further includes an opto-coupling circuit for generating a feedback signal according to the operation signal by opto-coupling, the feedback signal being fed back to the primary side circuit.