80VIN/80VOUT, Constant Voltage, Constant-Current dc/dc Converter

ELECTRONICS: Linear Technology announced the LT3956, an 80V high-side current sense dc/dc converter designed to operate as a constant-current and constant-voltage regulator. It is ideal for driving high current LEDs as well as charging batteries and supercaps. Its 4.5 to 80V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The LT3956 uses an internal N-channel MOSFET and can drive up to eighteen 350mA white LEDs from a nominal 12V input, delivering in excess of 25 Watts. It incorporates a high-side current sense, enabling use in boost, buck, buck-boost or SEPIC and flyback topologies. The LT3956 delivers efficiencies of over 94 percent in boost mode, eliminating the need for external heat sinking. A frequency adjust pin permits the user to program the frequency between 100 and 1MHz, optimizing efficiency while minimizing external component size and cost. Combined with a 5mm x 6mm QFN package, the LT3956 offers a highly compact 25W  LED driver solution.

The LT3956 uses True Color PWM^™ dimming, delivering constant LED color with dimming ranges up to 3,000:1. For less demanding dimming requirements, the CTRL pin provides a 10:1 analog dimming range. The LT3956’s fixed frequency, current mode architecture ensures stable operation over a wide range of supply and output voltages. A ground referenced voltage FB pin serves as the input for several LED protection features, enabling the converter to operate as a constant-voltage source.

The LT3956EUHE is available in a 36-pin 5mm x 6mm QFN package, priced starting at $3.50 each in 1,000-piece quantities. An extended temperature I-grade version, the LT3956IUHE, is priced at $4.12 each, in 1,000-piece quantities. Both versions are available from stock.

-Edited by Kelsey Anderson