DC/DC Controller powers AMD Hammer-based CPU platforms.

Press Release Summary:

Model LTC3733 consists of one PolyPhase® DC/DC synchronous step-down controller with integrated MOSFET drivers for powering single or multiple AMD® Hammer CPU platforms. Capable of delivering up to 120 A load current, unit provides ±5% current matching among its output channels. Its 5-bit VID interface allows CPU to vary output voltage from 0.8-1.55 V. Unit also offers adjustable or synchronizable operating frequency from 250-600 kHz.

Original Press Release:

PolyPhase DC/DC Controller Powers AMD Hammer-Based CPU Platforms, Eliminates MOSFET Drivers & Heat Sink

MILPITAS, CA - July 21, 2003 - Linear Technology Corporation introduces the LTC3733, a PolyPhase® DC/DC synchronous step-down controller with integrated MOSFET drivers for powering single or multiple AMD® Hammer CPU platforms without requiring heat sinks while delivering up to 120A of load current. The LTC3733 operates each of its three output channels 120°out of phase to facilitate heat dissipation, reduce MOSFET thermal stress, and minimize input and output capacitor requirements. PolyPhase operation also allows use of low profile and small size inductors.

Multiple LTC3733s can be synchronized with each other to construct a power supply that operates from 6 to 12 phases and is capable of delivering up to 200A of load current. With its integrated MOSFET drivers, a 6-phase 60A to 120A LTC3733 power supply design eliminates the need for five additional power ICs compared with competing solutions. Applications include high-end servers and graphic boards based on AMD Hammer technology CPUs such as AMD Athlon® and AMD Opteron® processors.

The LTC3733 guarantees precision ±5% current matching among its output channels thereby greatly reducing thermal stress and eliminating hot spots. The product eliminates the up to ±30% mismatch induced by incorporating MOSFET R DS(ON) sensing or inductor current sensing commonly used by competing solutions. A 5-bit VID interface allows the CPU to vary the output voltage of the LTC3733 from 0.8V to 1.55V. With the operating frequency adjustable or synchronizable from 250kHz to 600kHz, power supply designers can easily size the inductors and capacitors according to system height and space requirement or reduce noise interference.

The LTC3733 is offered in a narrow (5.2mm) 36-lead SSOP and 5mmx7mm QFN package.

Pricing for the 1,000-piece quantity starts at $4.35 each.

Summary of Features: LTC3733
o3-Phase Controller with Onboard MOSFET Drivers
oLTC3733 in QFN Expandable from 3-Phase to 12-Phase; 60A to 120A
oLTC3733 in SSOP: 3-Phase, 60A
oPrecision ±5% Output Current Matching Improves Thermal Performance
oDifferential Amplifier Accurately Senses V OUT
oVID Programmable from 0.8V to 1.55V
o250kHz to 600kHz per Phase Fixed Frequency Operation

Company Background

Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators,power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequencydevices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.

Note: LT, AND LTC are registered trademarks of Linear Technology Corp.

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