The LT3954 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator with an internal 5A switch. It's internal PWM dimming generator makes it ideal for driving high current LEDs, and is also suitable for charging batteries and super-capacitors.The 4.5V to 40V input voltage range suits a wide variety of applications, including automotive, industrial and architectural lighting.This device uses an internal 5A, 40V N-channel MOSFET and can drive up to eight 650mA white LEDs from a nominal 12V input, delivering in excess of 20 watts. It incorporates a high-side current sense, enabling use in boost mode, buck mode, buck-boost mode or SEPIC topologies.This device can deliver efficiencies of over 95% in the boost topology, eliminating the need for external heat sinking. A frequency adjust pin permits the user to program the frequency between 100kHz and 1MHz, optimizing efficiency while minimizing external component size and cost. Combined with a 5mm x 6mm QFN package, the LT3954 offers a highly compact high power LED driver solution. The internal PWM generator delivers dimming ratios as high as 25:1 or it can utilise an external PWM signal, delivering dimming ratios of up to 3,000:1. For less demanding dimming requirements, the CTRL pin can be used to provide a 10:1 analog dimming range. Its fixed frequency, current-mode architecture offers stable operation over a wide range of supply and output voltages.Output short-circuit protection and open LED protection enhance system reliability. The ground-referenced voltage FB pin serves as the input for several LED protection features.The LT3954EUHE is available in a 36-lead 5mm x 6mm QFN package, pricing starts at $3.60 each. An I-grade extended temperature version, the LT3954IUHE, is priced at $3.96 each based on 1,000-piece quantities.
