40-VIN /60-VOUT 5-A constant-current, constant-voltage converter incorporates internal PWM generator

40-VIN /60-VOUT 5-A constant-current, constant-voltage converter incorporates internal PWM generator

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By eeNews Europe

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

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