Integrated PWM waveform generation in CC/CV converter
The LT3954 uses an internal 5A, 40V N-channel MOSFET and can drive up to eight 650mA white LEDs from a nominal 12V input, delivering in excess of 20W. 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 100kHz and 1MHz, optimising efficiency while minimising external component size and cost. Combined with a 5 x 6mm 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 use 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 analogue dimming range. Its fixed frequency, current-mode architecture offers stable operation over a wide range of supply and output voltages, with utput short-circuit protection and open LED protection. 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.
The LT3954EUHE is available in a 36-lead 5 x 6mm QFN package.
More at; www.linear.com/product/LT3954
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