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Synchronous step-down controller

Linear Technology has introduced the LT3741, a synchronous, step-down DC/DC converter designed to accurately regulate output currents up to 20A. Its 6 to 36V input voltage range, constant-current and constant-voltage operation make it suitable for a variety of applications, ranging from battery and supercap chargers and laser drivers to high-current LED lighting. The device uses two external switching MOSFETs and delivers up to 20A of continuous output current over a wide voltage range from 0 to 34V. High efficiency eliminates the need for external heat sinking. The device's frequency can be programmed and synchronised between 200kHz and 1MHz, allowing designers to optimise efficiency while minimising external component size. Combined with a 4x4mm QFN20 or thermally-enhanced TSSOP20 package, the device provides a highly compact constant voltage and current solution. The device 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 analogue voltage on the CTRL pins and an external sense resistor. The device's advanced topology enables it to both source and sink current.