SC1471 Datasheet, PDF (1/1 Pages) Semtech Corporation – Power Supply Controller for Portable Pentium III SpeedStep Processors

SC1471
Power Supply Controller for Portable
Pentium^® III SpeedStep™ Processors
POWER MANAGEMENT
Description
.eatures
The SC1471 PowerStep™ II controller is a high speed,
high performance hysteretic mode PWM controller.
Teamed with the SC1405 Smart Driver™ , it powers ad-
vanced Intel^® Pentium^® III processors. The SC1471 fea-
tures extended Intel Mobile Voltage Positioning (IMVP) to
increase battery life by reducing the voltage at the pro-
cessor when it is heavily loaded. It directly supports Intel^®
SpeedStep™ processors for even longer battery life, in-
cluding IMVP extensions. The SC1471 incorporates di-
rect “deeper sleep” mode support, which eliminates an
external multiplexer in many applications.
A 5-bit DAC, accurate to 0.85%, sets the output voltage
reference and implements the 0.600V to 1.750V 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 SC1471 operates from either 3.3Vdc or 5Vdc Vcc
and also features soft-start, an open-drain power-good
indication with power-good blanking, and an enable in-
put. Programmable current limiting uses a separate com-
parator to protect against overloads and short-circuits.
In addition, it comes in a space-saving TSSOP-24 pack-
age.
K Direct “deeper sleep” mode support
K High-speed hysteretic controller provides high
efficiency over a wide operating load range
K .astest possible transient response
K Inherently stable
K Integrated extended IMVP support
K Programmable core voltage for Pentium^® III proces-
sors
K Native Intel^® SpeedStep™ support with PWRGD
blanking
K Proportional overvoltage protection
K Overcurrent shutdown after 32 overcurrent pulses
K SC1471A also available for VID controlled “Deeper
Sleep” mode
Applications
K Laptop and notebook computers
K High performance microprocessor-based systems
K High efficiency distributed power supplies
Typical Application Circuit
+V_5
+V_IN
Power
Control
Signals
PWM
Controller
SC1471
Extended IMVP
CONTROLLER
SC1405C
Smart
MOSFET
Driver
Lo
+VCC_CPU_CORE
0.600V-1.75V
Co
Up to 25A
VID [4:0]
Control
Signals
Exte nded
IMVP
Logic
Revision 2, March 2001
1
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