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Portable IMVP-IV™ and IMVP-IV+™
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DataSheet
Single Phase Power Supply Controller
POWER MANAGEMENT
Description Features
The SC451 PowerStep IV™ IC is a single chip high-performance Hysteretic PWM controller. With its integrated
SmartDriver™, it powers advanced IMVP-IV™ and IMVP4+™
processors. The SC451 features extended Intel Mobile Voltage Positioning (IMVP™) to increase battery life by reducing the voltage at the processor when it is heavily loaded.
It directly supports Intel’s SpeedStep® processors for even
longer battery life. The SC451 fully supports the Intel®
Geyserville-III core voltage specification. It provides direct
“deeper sleep” mode and boot voltage support. Automatic
“power-save” is present to prevent negative current flow in
the low-side FET during light loading conditions, saving even
more power. The high side driver initially turns on with a
weak drive to reduce ringing, EMI, and capacitive turn-on
of the low side.
A 6-bit DAC, accurate to 0.85%, sets the output voltage
reference, and implements the 0.700V to 1.708V range
required by the processor. The hysteretic converter uses a
comparator without an error amplifier, and therefore provides the fastest possible transient response, while avoiding the stability issues inherent to classical PWM controllers. The DAC is externally slew rate limited to minimize
transient currents and audible noise.
The SC451 operates from 5Vdc and also features soft-start,
an open-drain PWRGD signal with power-good blanking,
and an enable input. Programmable current limiting shuts
down the SC451 after 32 current limit pulses. In addition,
it comes in a space-saving MLP 6X6-28 and TSSOP-28
package. TSSOP-38 package is also available which provides a pin to pin upgrade to a dual phase solution using
Semtech’s dual phase controller SC450.
IMVP-IV™ and IMVP-IV+™ compliant single chip
solution
On chip CLK_ENABLE# and IMVP4_PWRGD outputs
Backward compatible with SC1479
High speed hysteretic controller
Single phase operation
Selectable analog or VID controlled DeeperSleep
setting
6 bit VID programmable output
Integrated drivers with soft high side turn-on
Programmable softstart
Programmable boot voltage
Programmable DeeperSleep voltage
Under-voltage lock out on VccA
Over-voltage protection on CORE
Current limit protection on CORE
Thermal protection
Powergood flag with blanking during VID or
DeeperSleep mode changes
Automatic powersave at light load
TSSOP-28, TSSOP-38 and MLP 6X6-28 package
options
Applications
Low power Notebook and Laptop computers
Embedded Applications
PowerStep IV™ is a trademark of Semtech
Corporation.
Other trademarks or registered trademarks may be
claimed as the property of others.
SC451
Conceptual Application Circuit
February 2, 2005
VID (5:0)
V
CCA
SC451 Single Phase
IMVP -IV /IM VP -IV +
Power Supply
VID Logic
and DAC
V
5
Smart
Driver
PWM
Controller
1 www.semtech.com
VIN
VCORE
0.700V-1.708V
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