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High Power, Constant Current/Constant Voltage, Synchronous Step-Down Controller

22nd March 2010

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Linear Technology announces the LT3741, a synchronous step-down DC/DC converter designed to accurately (±6%) regulate output currents up to 20A. Its 6V to 36V input voltage range, constant current and constant voltage operation makes it ideal for a wide variety of applications, ranging from battery and supercap chargers and laser drivers to high current LED lighting. The LT3741 uses two external switching MOSFETs and delivers up to 20A of continuous output current over a wide voltage range of 0V to 34V.

Efficiencies as high as 95% eliminate the need for external heat sinking. The LT3741's frequency can be programmed and synchronized between 200kHz and 1MHz, allowing designers to optimize efficiency while minimizing external component size. Combined with a 4mm x 4mm QFN-20 or thermally enhanced TSSOP-20 package, the LT3741 provides a highly compact constant voltage and current solution.

The LT3741 uses an average current mode control scheme to maintain inductor current regulation over a wide output voltage range of 0V to VIN-2V. The regulated current is set by an analog voltage on the CTRL pins and an external sense resistor. The LT3741's unique topology enables it to both source and sink current. The LT3741's regulated output voltage and overvoltage protection are set with an external voltage divider. Additional features include an accurate external voltage reference, a programmable undervoltage lockout (ULVO) pin and thermal shutdown.

The LT3741EUF is available in a 20-pin 4mm x 4mm QFN package and the LT3741EFE is available in a thermally enhanced TSSOP-20, priced starting at $3.95 and $4.10 each, respectively in 1,000-piece quantities. Extended temperature versions, or “I” Grades, the LT3741IUF and LT3741IFE, are also available.