60V Step-Down LED Driver

Linear Technology's LT3597 is a 60V, 1MHz,step-down dc/dc converter designed to operate as a three channel, constantcurrent LED driver. Each channel of the LT3597 contains a constant current sinkLED driver with a dedicated adaptive-output buck converter. This design offersmaximum efficiency for applications, such as RGB displays, which requiredifferent output voltages for each LED string. From a 48V input, the LT3597 candrive up to three strings of LEDs, each with up to ten 100mA LEDs in series,delivering efficiencies of over 90 percent. The LT3597's multichannelcapability makes it useful for backlighting LED billboards as well asindustrial, automotive and medical displays. Similarly, its input voltage rangeof 6 to 60V makes it well suited for industrial, automotive and medicalapplications. Each LED string can be independently programmed to deliver up to100mA of LED current with plus or minus 2 percent current matching between strings. Eachchannel can be independently dimmed with True Color PWM dimming, offeringdimming ratios as high as 10,000:1. A programmable 200kHz to 1MHz fixedfrequency operation and current-mode architecture ensures stable operation overa wide range of supply and output voltages, minimizing the size of externalcomponents. The switching frequency is synchronizable to an external clock. TheLT3597's thermally enhanced 5 x 8mm QFN package provides a compact solutionfootprint for LED lighting applications.

The LT3597 uses threeindependent 400mA, 60V internal switches to provide step-down constant currentsources. The internal buck converters use an adaptive feedback loop to regulatethe output voltage slightly higher than the required LED voltage to ensuremaximum efficiency. If any of the LED strings experience an open orshort-circuit, the LT3597 will continue to regulate the other strings andsignal the FAULT pin. Additional features include LED current derating based onjunction temperature and/or LED temperature and LED disconnect in shutdown.

An industrial gradeversion, the LT3597IUHG is tested and guaranteed to operate from a -40 to 125Coperating junction temperature.

60V Step-Down LED Driver