Multiphase Step-Up DC/DC Controller From Linear Technology

9th December 2008

ES Admin

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Linear Technology has introduced the LTC3862, a 2-phase step-up (boost) DC/DC controller that delivers high output power in a compact footprint. Up to 12 power stages can be paralleled and clocked out-of-phase to minimize input and output filtering requirements. The 4V to 36V input voltage range and a wide output voltage range that is dependent on the choice of external components covers a broad range of high power boost applications.

The LTC3862 can regulate a 48V at 5A output with up to 97% efficiency from an input source ranging from 12V to 36V using only two-phases. Applications include high power audio amplifiers, automotive fuel injection systems, networking and industrial power supplies.

Multiphase operation is enabled using the SYNC input, CLOCK output and PHASEMODE control pin, allowing 2-, 3-, 4-, 6- or 12-phase operation. The LTC3862 utilizes peak current mode architecture for easy loop compensation and multi-phase operation with excellent phase-to-phase current matching. The fixed operating frequency can be set with a single resistor over a 75kHz to 500kHz range or can be synchronized to an external clock using the internal phased-lock-loop over a 50kHz to 600kHz frequency range. A current sense resistor is used in each phase to provide a precise cycle-by-cycle current limit. The powerful on-board CMOS gate drivers minimize switching losses and allow the use of multiple MOSFETs in parallel for even higher current applications. Other features include an on-board 5V LDO that eliminates the need for a bias voltage to power the IC, undervoltage lockout protection, a precise RUN pin threshold with programmable hysteresis, adjustable soft-start, programmable maximum duty cycle and user-adjustable leading edge blanking.

The LTC3862 is offered in narrow SSOP-24 and 5mm x 5mm QFN-24 package. Three temperature grades are available with commercial grade operation from -40 to 85°C, an industrial range from -40°C to 125°C, and a high temp automotive range of -40°C to 150°C. The 1,000-piece price starts at $3.29 each.