The LM3433 is an adaptive constant on-time DC/DC buck(step-down) constant current controller (a true currentsource). The LM3433 provides a constant current for illuminatinghigh power LEDs. The output configuration allows theanodes of multiple LEDs to be tied directly to the ground referencedchassis for maximum heat sink efficacy. The highfrequency capable architecture allows the use of small externalpassive components and no output capacitor while maintaininglow LED ripple current. Two control inputs are used tomodulate LED brightness. An analog current control input isprovided so the LM3433 can be adjusted to compensate forLED manufacturing variations and/or color temperature correction.The other input is a logic level PWM control of LEDcurrent. The PWM functions by shorting out the LED with aparallel switch allowing high PWM dimming frequencies. Highfrequency PWM dimming allows digital color temperaturecontrol, interference blanking, field sequential illumination,and brightness control. Additional features include thermalshutdown, VCC under-voltage lockout, and logic level shutdownmode. The LM3433 is available in a low profile LLP-24package.