There are many cases where the supply voltage is tentative. A variety of indicator lights on power supplies, for example, are often driven by the unregulated supply, which can move back and forth by 50% even in normal operation. This voltage swing becomes harsh for LED lamps. Especially for those LEDs whose elimination or alternation is difficult. Similarly, automotive applications have another problem, as the electrical system of a car can swing between as little as 6V during starting to as much as 18V when charging. This article presents a circuit that will protect the LED from over current for a wide range of voltage swing. The circuit proposed is fast acting and also serves for a driver to the LED.