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SC451
Portable IMVP-IVTM and IMVP-IV+TM
Single Phase Power Supply Controller
POWER MANAGEMENT
Revision: July 21, 2004
Description
Features
Applications
Conceptual Application Circuit
IMVP-IVTM and IMVP-IV+TM 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
The SC451 PowerStep IVTM IC is a single chip high-perfor-
mance Hysteretic PWM controller. With its integrated
SmartDriverTM, it powers advanced IMVP-IVTM and IMVP4+TM
processors. The SC451 features extended Intel Mobile Volt-
age Positioning (IMVPTM) to increase battery life by reduc-
ing 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 pro-
vides the fastest possible transient response, while avoid-
ing the stability issues inherent to classical PWM control-
lers. 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 pro-
vides a pin to pin upgrade to a dual phase solution using
Semtech's dual phase controller SC450.
Low power Notebook and Laptop computers
Embedded Applications
PowerStep IVTM is a trademark of Semtech
Corporation.
Other trademarks or registered trademarks may be
claimed as the property of others.
S C 4 51 S ingle P ha se
IM V P -IV /IM V P -IV +
P ow er S u pply
S m art
D river
P W M
C o ntroller
V ID Logic
and D A C
V ID (5:0)
V IN
V
5
V
C C A
V C O R E
0.700V -1.708V
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