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POWER MANAGEMENT

SC2646B

2, 3 or 4 Phase

Revision: Apr. 11, 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 mini-

mizes the core voltage ripple and the input current ripple,

which leads to optimized voltage regulator design for

power density, transient responses, and thermal

performances.

To satisfy the highly dynamic nature of the modern micro-

processors, the SC2646B adopts peak current mode

control topology which ensures wide control loop band-

width 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 pro-

vide 0.5% set point accuracy, but also the accuracy to

be fully compliant with stringent load line slope specifi-

cations mandated by the modern microprocessors.

Lossless output current sensing ensures the regulator

output voltage is accurately positioned according to the

load current condition.

by SC2646B controller. The MOSFET R

put inductor winding resistance is used to generate the

phase current information. Semtech’s SC1211 Combi-

able a complete solution.

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

current shut down provide the maximum versatility of

the system without false tripping under all possible

changes of VID and load conditions. The differential

voltage feedback sense eliminates the error caused by

high load current on the ground plane. External offset is

easy to achieve for the VID settings. The enable func-

tion is also provided to interface with the corresponding

system signal for correct start up timing and shut down

timing.

VRD/VRM10.X compliant

Core Voltage Set Point Accuracy 0.5%

Intrinsic Phase Current Matching

Fast Transient Responses

Active Droop to Meet Load Line Slope

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

Externally Programmable Soft-Start

Externally Programmable Switching Frequency

2, 3, or 4-Phase Configurations

24-Pin TSSOP Package

Voltage Regulator VRD/VRM10.X

Voltage Regulation Modules

High Current, Low Voltage Step Down DC/DC

Converters

Features