An integrated Schottky diode dual high efficiency white LED driver

Ling Li (Linear Technology) announced the launch of dual, full function, boost DC/DC converter LT3497, the device from the lithium ion battery input drive up to 12 white LED. Its high efficiency, fixed frequency operation to ensure uniform LED brightness and low noise and maximize battery life, the on-chip Schottky diode, so no external diode, which saves cost and space. True Color PWMTM dimming achieve up to 250:1 dimming range, while the LED does not change any color. The LT3497's two independent converters are capable of driving asymmetrical LED strings (up to 6 series LED) for each converter with an input voltage of 2.5V to 10V. The 3mm x 2mm DFN package and tiny external components can be composed of solution extremely compact footprint for handheld applications with limited space.

The 2.3MHz constant switching frequency of the LT3497 enables the designer to minimize the solution to account for board area and switching noise. The input voltage range of 2.5V to 10V allows the device to be used for handheld applications powered by a single or two Li ion battery and an application of the 5V fixed input power supply. High current detection allows the use of a single line driver for each LED string. LT3497 has a constant current source, is responsible for delivering the same current to each white LED, but not affected by the fluctuation of LED forward voltage drop (the pressure will change with temperature, manufacturing tolerances and aging), so as to ensure the uniformity of the brightness of LED. Although the two independent boost regulators can drive asymmetric LED strings on the same chip, each of the LED strings has independent dimming and shutdown control. Other features include internal soft start / inrush current limiting and LED open circuit protection. The solution LT3497 has high efficiency, versatility, low noise and small overall area, very suitable for backlighting applications in various shapes and sizes of tiny but need a lot of white LED. LT3497 uses 3mm x DFN-10 2mm package, available from stock. In 1000 pieces for the bulk purchase, each price starts at $1.70. Summary: - Performance 3V power drive up to 12 white LED (each 6 LED converter series) - two independent step-up converter capable of driving on asymmetric LED dimming - two LED on independent and stop control - high side detection allows each transducer adopts single type current source "internal Schottky diode, LED open circuit protection (32V) - 2.3MHz - switching frequency reference accuracy + 5% - VIN range: 2.5V to 10V - two converter has a wide 250:1 True Color PWM dimming range - each converter only 1 F output capacitor using the 3mm x 2mm 10 pin DFN package