40-VIN /60-VOUT 5-A constant-current, constant-voltage converter incorporates internal PWM generator
The LT3954 internal PWM dimming generator makes it ideal for driving high current LEDs, and it also has features suitable for charging batteries and supercapacitors. The device’s 4.5 V to 40 V input voltage range suits a wide variety of applications, including automotive, industrial and architectural lighting.
The LT3954 uses an internal 5 A, 40 V N-channel MOSFET and can drive up to eight 650 mA white LEDs from a nominal 12 V 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. The LT3954 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 100 kHz and 1 MHz, optimizing efficiency while minimizing external component size and cost. Combined with a 5 mm x 6 mm QFN package, the LT3954 offers a highly compact high power LED driver solution.
The LT3954 has an internal PWM generator that delivers dimming ratios as high as 25:1 or it can utilize 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 LT3954’s ground-referenced voltage FB pin serves as the input for several LED protection features and makes it possible for the converter to operate as a constant-voltage source for charging applications.
Availability and Pricing
The LT3954EUHE is available in a 36-lead 5mm x 6mm QFN package. Pricing starts at $3.60 each. An extended temperature version, or I grade, the LT3954IUHE, is also available, priced starting at $3.96 each. All pricing is based on 1,000-piece quantities and both versions are available from stock.
More information about LT3954 DC/DC converter at www.linear.com/product/LT3954