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POWER MANAGEMENT

SC2646B

2, 3 or 4 Phase

Revision: Sept. 12, 2005

Description

Applications

The SC2646B controller provides a microprocessor core

voltage regulation solution for up to 4 paralleled PWM

channels. The solution can be configured in 2, 3, or 4-

phase form. This multi-phase buck regulator utilizes

phase-shift timing control to allow interleaved switching of

the power switches. The product’s architecture minimizes

the core voltage ripple and the input current ripple, which

leads to optimized voltage regulator design for power den-

sity, transient responses, and thermal performances.

To satisfy the highly dynamic nature of the modern micro-

processors, the SC2646B 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 2MHz.

One of the outstanding features of the SC2646B device is

its voltage regulation accuracy. Not only does it provide

0.5% set point accuracy, but also the accuracy to be fully

compliant with stringent load line slope specifications man-

dated by the modern microprocessors. Lossless output

current sensing ensures the regulator output voltage is

accurately positioned according to the load current condi-

tion.

by SC2646B controller. The MOSFET R

inductor winding resistance is used to generate the phase

MOSFET driver works with the SC2646B to enable a com-

plete solution.

The cycle-by-cycle current limit plus the intelligent over cur-

rent shut down provide the maximum versatility of the sys-

tem without false tripping under all possible changes of

VID and load conditions. The differential voltage feed-

back sense eliminates the error caused by high load cur-

rent on the ground plane. External offset is easy to achieve

for the VID settings. The enable function is also provided

to interface with the corresponding system signal for cor-

rect start up timing and shut down timing.

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VRD/VRM10.X compliant

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Core Voltage Set Point Accuracy 0.5%

!

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Intrinsic Phase Current Matching

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Fast Transient Responses

!

Active Droop to Meet Load Line Slope

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Enable Function for Power Sequencing

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Cycle-by-Cycle Peak Current Limit

!

Intelligent Over Current Shut Down

!

Over Voltage Protection When Using Semtech

!

Under Voltage Protection Built in

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Externally Programmable Soft-Start

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Externally Programmable Switching Frequency

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2, 3, or 4-Phase Configurations

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24-Pin TSSOP Package

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Voltage Regulator VRD/VRM10.X

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Voltage Regulation Modules

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High Current, Low Voltage Step Down DC/DC

Converters

Features