Constant voltage converter features internal PWM generator
Linear Technology has announced the LT3954, a dc/dc converter designed to operate as a constant current source and constant voltage regulator with an internal 5A switch.
Available in a 5 x 6mm QFN package with a 4.5 to 40V input voltage range, the device features an internal PWM dimming generator that delivers dimming ratios up to 25:1.
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.
A frequency adjust pin permits the user to program the frequency between 100kHz and 1MHz. 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 is optimised to offer stable operation over a range of supply and output voltages.
