This article describes a simple circuit for regulating the current through high-brightness LEDs. The design includes an off-the-shelf, highly integrated step-down switching regulator (the MAX5035), which allows accurate control of the LED current. The MAX5035 DC/DC converter operates on a fixed frequency of 125 kHz with wide 7.5 V to 76 V input-voltage range especially useful for automotive applications. For brightness control, this converter implements either analog (linear dimming) or low-frequency duty-cycle modulation (PWM dimming).