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POWER MANAGEMENT

SC458

Complete Dual-Phase Low VOUT

Power Supply Controller

October 31, 2006

United States Patents: 6,504,422, 6,794,926

www.semtech.com

Applications

Features

The SC458 is a single chip high-performance PWM

controller designed to power advanced processors. On-

chip support is provided for Active Voltage Positioning, “VID

on-the-fly” transitions, single and dual phase control.

The SC458 implements hysteretic control technology

which provides the fastest possible transient response

while avoiding the stability issues inherent to classical

PWM controllers. Semtech’s proprietary Combi-Sense®

technology provides a loss-less current sensing scheme

which is extremely robust and easy to lay out. Eliminating

the sense resistors reduces costs and PCB area, plus

increases system efficiency. Integrated SmartDriver™

technology initially turns on the high side driver with ‘soft’

drive to reduce ringing, EMI, and capacitive turn-on of the

low side MOSFET, while also increasing overall efficiency.

Hysteretic operation adaptively reduces the SC458

switching frequency at light loads. Combined with an

automatic “power-save” mode which prevents negative

current flow in the low-side FET, system efficiency is

significantly enhanced during light loading conditions.

The SC458 changes from dual-phase to single-phase

operation whenever DUAL transitions low, providing

optimal efficiency across the entire power range.

A

second low power control pin, DRIFT, allows the output

voltage to be discharged by the load during a negative

voltage transition.

A 7-bit DAC, accurate to 0.85%, sets the output voltage

reference, and implements a 0.300V to 1.500V range.

The DAC slew rate is externally programmed to minimize

transient currents and audible noise. True differential

remote sensing provides accurate point-of-load regulation

at the processor die. Other features include programmable

soft-start, dual (delayed, and not delayed) power good

outputs, dynamic current sharing, over voltage and

programmable over current protection. The SC458 is

available in a space- saving 44 pin MLP package.

Dual-Phase Solution with Integrated Drivers

Hysteretic Control for Fast Transient Response

Combi-Sense Loss-Less Current Sensing

Dynamic Current Sharing

Active Voltage Positioning

True Differential Remote Sensing

Dual Power Good Outputs

Programmable Soft-Start and DAC Slew Control

Programmable OCP Threshold

Supports all Ceramic Decoupling Solutions

44 pin MLP (7x7 mm)

Product is WEEE and RoHS Compliant

Graphics and other Processor Cores

Notebook PCs

Embedded Applications

Description

NOT RECOMMENDED FOR NEW DESIGN