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POWER MANAGEMENT

SC2643VX

Multi-Platform

Multi-Phase PWM Controller

May 11, 2005

Description

Applications

The SC2643VX provides a solution for microprocessor core

voltage regulation with up to 4 paralleled PWM channels.

The solution can also be configured as 2, 3, or 4-phase

form. This multi-phase buck regulator utilizes the phase-

shift timing control to allow interleaved switching of the

power switches. This architecture minimizes the core volt-

age ripple and the input current ripple, which leads to op-

timized voltage regulator design for power density, tran-

sient responses, and the thermal performances.

To satisfy the highly dynamic nature of the modern micro-

processors, the SC2643VX adopts peak current mode con-

trol topology which ensures wide control loop bandwidth

and fast transient responses. The current mode control

provides intrinsic phase current matching. The maximum

ripple frequency is greater than 2.8MHz.

One of the outstanding features of the SC2643VX is its

voltage regulation accuracy. Not only does it provide bet-

ter than 0.5% set point accuracy, but also the accuracy to

be fully compliant with stringent load line slope specifica-

tions mandated by the modern microprocessors. Lossless

output current sensing ensures the regulator output volt-

age is accurately positioned according to the load current

condition, and an internal temperature compensation tech-

nology further enhances the performance of voltage accu-

racy.

SC2643VX. The MOSFET R

winding resistance are used to generate the phase current

SC2643VX enables the complete solution.

The SC2643VX is a multi-platform controller. It conforms

VID specifications. With very minor changes of the sche-

matic and the layout, the SC2643VX based solution can

be ported form one platform to another. This greatly ben-

efits system manufactures by reducing design cycle times

and streamlining inventory management.

The SC2643VX supports VID-on-Fly applications for any

platform. The cycle-by-cycle current limit plus the intelli-

gent over current shut down provide the maximum versa-

tility of the system without false tripping under all possible

changes of VID and load conditions. The differential volt-

age feedback sense eliminates the error caused by high

VRD/VRM10.X, VRM9.X, and K-8 compliant

Core Voltage Set Point Accuracy 0.5%

Intrinsic Phase Current Matching

Fast Transient Responses

Active Droop with Temperature Compensation to

Meet Load Line Slope

Support VID-on-Fly with 5 or 6 bit VID

Enable Function for Power Sequencing

Cycle-by-Cycle Peak Current Limit

Intelligent Over Current Shut Down

Over Voltage Protection When Using Semtech

Under Voltage Protection Built in

External programmable Soft-Start

Externally programmable switching frequency (up to

2.8MHz output voltage ripple frequency)

2, 3, or 4-Phase Configurations

Voltage Regulator VRD/VRM10.X

Voltage Regulator VRM9.X

Voltage Regulator K-8

High Current, Low Voltage Step Down DC/DC

Converters

Features

load current on the ground plane. External offset is easy

to achieve for any platforms and the VID settings. The

enable function is also provided to interface with the cor-

responding system signal for correct start up timing and

shut down timing.

(Multiple Patents Pending)

(Multiple Patents Pending)

(Multiple Patents Pending)

(Multiple Patents Pending)

(Multiple Patents Pending)