Design and Implementation of the Linear LED Driver

This brief presents a new LED control scheme to maintain a constant LED power. In LED control schemes, the conventional approach is to maintain a constant LED current. However, this traditional approach will bring high power at high input voltage and then generate high heat. The higher heat will shorten the life time of the product and reduce the reliability. The proposed scheme can solve this problem. The LED driver with the proposed scheme has been successfully fabricated by Macronix and the feasibility of the method has been verified. From the experimental results, the higher the input voltage, the lower the LED current. This constant power method can effectively avoid overheating at high input voltage. The control scheme, the theoretical analysis and the circuit implementation are presented in this brief.