LEDs are current driven devices with a characteristic I-V curve and a characteristic forward voltage which needs to be exceeded in order to turn ‘ON' the LED. Once the forward voltage is exceeded the LED's resistance begins to decrease causing the LED to draw greater current and potentially burn out. A resistor is typically used in series with the LED to limit the current and prevent LED burn out. However, any variation in resistor voltage resulting from temperature and supply voltage will cause a proportional variation in the LED current resulting in variation of LED brightness. The ultimate solution to driving LEDs is to use an LED driver with a constant current regulator to provide the exact LED current regardless of variations in supply voltage or temperature. The LED driver IC solutions provide the optimum current for longevity and increased reliability of LEDs. In addition, because LED drivers are semiconductor devices, they can integrate special functions for advance LED control.