PROGRAMMABLE SYNCHRONOUS DC/DC
CONTROLLER FOR ADVANCED PROCESSORS
Preliminary - August 7, 2000
SC1157
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1157 is a low-cost, full featured, synchronous
voltage-mode controller designed for use in single
ended power supply applications where efficiency is of
primary concern. Synchronous operation allows for the
elimination of heat sinks in many applications. The
SC1157 is ideal for implementing DC/DC converters
needed to power advanced microprocessors such as
Pentium
廬
ll (Klamath), in both single and multiple pro-
cessor configurations. Internal level-shift, high-side
drive circuitry, and preset shoot-thru control, allows for
use of inexpensive n-channel power switches.
SC1157 features include an integrated 4-bit V
ID
DAC,
temperature compensated voltage reference, triangle
wave oscillator, current limit comparator, frequency
shift over-current protection, and an internally compen-
sated error amplifier.
The SC1157 operates at a fixed 140KHz, providing an
optimum compromise between efficiency, external
component size, and cost.
FEATURES
鈥?
Low cost / full featured
鈥?
Synchronous operation
鈥?
4 Bit V
ID
DAC programmable output
鈥?
鈥?
(1% tolerance)
Designed to meet Intel VRM8.2 (Pentium
廬
II)
1.5% Reference
APPLICATIONS
鈥?
Pentium廬 II Core Supply
鈥?
Multiple Microprocessor Supplies
鈥?
Voltage Regulator Modules (VRM)
鈥?
Programmable Power Supplies
鈥?
High Efficiency DC/DC Conversion
ORDERING INFORMATION
DEVICE
(1)
PACKAGE
(2)
TEMP. RANGE (T
J
)
0 - 125擄C
SC1157CS.TR
SO-16NB
Note:
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
(2) 鈥淣B鈥?indicates 150 MIL body.
PIN CONFIGURATION
BLOCK DIAGRAM
Top View
VCC
CS-
CS+
SHUTDOWN
CURRENT
LIMIT
REF
REF
BSTH
70mV
+
-
LEVEL SHIFT AND
HIGH SIDE DRIVE
VID3
VID2
VID1
VID0
VOSENSE
D/A
DH
+
-
-
ERROR
AMP
+
R
OSCILLATOR
Q
S
SHOOT-THRU
CONTROL
GND
BSTL
(16-Pin SOIC)
SYNCHRONOUS
MOSFET DRIVE
DL
PGND
Pentium is a registered trademark of Intel Corporation
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漏 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
SEMTECH
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