Current-mode step-up DC-DC converter integrates 60V, 4A DMOS power switch

The LT3952 is a new current-mode step-up DC-DC converter, from Linear Technology, with an internal 60V, 4A DMOS power switch. A highly-compact solution, it is specifically designed to drive high-power LEDs in multiple configurations. The device combines input and output current regulation loops with output voltage regulation to operate as a flexible current/voltage source. The LT3952’s 3V to 42V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The LT3952 can drive up to sixteen 350mA white LEDs from a nominal 12V input, delivering in excess of 15W. It incorporates a high side current sense, enabling its use in boost mode, buck mode, buck-boost mode or SEPIC topologies. Internal spread spectrum frequency modulation minimizes EMI concerns. The LT3952 delivers efficiencies of over 94% in the boost topology, eliminating the need for external heat sinking, and internal LED short-circuit protection enables added reliability required in most applications. A frequency adjust pin permits the user to program the switching frequency between 200kHz and 3MHz, optimizing efficiency while minimizing external component size and cost. The LT3952 delivers over 90% efficiency while switching at 2MHz in a tiny solution footprint. The LT3952 has a gate driver for a PMOS LED disconnect switch, delivering dimming ratios of up to 4,000:1 using an external PWM signal. For less demanding dimming requirements, the CTRL pin can be used to offer a 10:1 analog dimming range and an internal PWM generator can be used for 5:1 dimming. The LT3952’s fixed frequency, current-mode architecture offers stable operation over a wide range of supply and output voltages. Output short-circuit protection and open LED protection enhance system reliability. Other features include frequency synchronization, spread spectrum frequency modulation, programmable VIN under-voltage and over-voltage protection, and an input current limit and monitor. The LT3952EFE is available in a thermally-enhanced 28-lead TSSOP package. Three temperature grades are available, with operation from -40C to 125C (junction) for extended and industrial grades, and a high-temperature grade of -40C to 150C.