SC457
POWER MANAGEMENT
Description
The SC457 is a single phase, high performance PWM con-
troller designed to power advanced processors. On-chip
support is provided for VID on-the-鏗倅 transitions and active
voltage positioning.
The SC457 implements hysteretic control technology
providing the fastest possible transient response while
avoiding the stability issues inherent to classical PWM
controllers. Eliminating the sense resistors reduces costs
and PCB area while increasing system ef鏗乧iency. Integrated
SmartDriver鈩?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 increasing overall
ef鏗乧iency.
Hysteretic operation adaptively reduces the SC457 switch-
ing frequency at light loads. Combined with an automatic
power-save mode which prevents negative current
鏗?/div>
ow in
the low-side FET, system ef鏗乧iency is signi鏗乧antly enhanced
during light loading conditions.
A 7-bit DAC, accurate to 0.85%, sets the output voltage
reference and implements the 0.300V to 1.500V range
required by the processor. 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, open-drain PG_DEL and
PG# outputs, dynamic current sharing, over-voltage and
programmable over-current protection. The SC457 is avail-
able in a space-saving 32-pin MLP package.
Single-Phase Single Chip
Vcore Power Supply
Features
Single-Phase Solution with Integrated Drivers
Hysteretic Control for Fast Transient Response
Active Voltage Positioning
True Differential Remote (die) Sensing
On-Chip Support for all Power Management
Features
Programmable Soft-Start and DAC Slew Control
Programmable OCP Threshold
Supports all Ceramic Decoupling Solutions
32-Pin MLP (5x5) - product is WEEE and RoHS
compliant
Default 1.2V Boot Voltage
Soft OFF State
Applications
Notebook PCs
Embedded Applications
Graphics and other Processor Cores
April 12, 2006
1
www.semtech.com
SEMTECH
1
