LED current regulator has low dropout

Peter Demchenko @ edn.com

This Design Idea circuit regulates the current through one or more LEDs, making it almost independent of supply voltage. Its main advantage is a very small dropout voltage, which can be less than 100mV. The design could find use on LED strips, where the voltage can vary along the length due to resistive drop, and small voltage changes result in large current changes

LED current regulator has low dropout – [Link]