SC1172 Datasheet, PDF (1/12 Pages) Semtech Corporation – PROGRAMMABLE SYNCHRONOUS DC/DC CONVERTER WITH LOW DROPOUT REGULATOR CONTROLLER

October 25, 1999
PROGRAMMABLE SYNCHRONOUS DC/DC
CONVERTER WITH LOW DROPOUT
REGULATOR CONTROLLER
SC1172/3
TEL:[phone] FAX:[phone] WEB:http://www.semtech.com
DESCRIPTION
The SC1172/3 combines a synchronous voltage mode
controller with a low-dropout linear regulator providing
most of the circuitry necessary to implement two DC/DC
converters for powering advanced microprocessors such
as Pentium^® II (Klamath) or Deschutes.
The SC1172/3 switching section features an integrated 5
bit D/A converter, pulse by pulse current limiting,
integrated power good signaling, and logic compatible
shutdown. The SC1172/3 switching section operates at
a fixed frequency of 200kHz, providing an optimum
compromise between size, efficiency and cost in the
intended application areas. The integrated D/A con-
verter provides programmability of output voltage from
2.0V to 3.5V in 100mV increments and 1.30V to 2.05V
in 50mV increments with no external components.
The SC1172/3 linear section is a high performance
positive voltage regulator design for either the GTL bus
supply at 1.5V (SC1172) or an adjustable output
(SC1173).
The output of the linear regulator can provide up to 5A or
more with the appropriate external MOSFET.
FEATURES
• Synchronous design, enables no heatsink solution
• 95% efficiency (switching section)
• 5 bit DAC for output programmability
• On chip power good function
• Designed for Intel Pentium^® II VRM8.1 require-
ments
• 1.5V or Adj. @ 1% for linear section
APPLICATIONS
• Pentium^® ll or Deschutes microprocessor supplies
• Flexible motherboards
• 1.3V to 3.5V microprocessor supplies
• Programmable dual power supplies
ORDERING INFORMATION
Part Number⁽¹⁾ Package
Linear
Voltage
SC1172CSW SO-24 1.5V
Temp.
Range (T_J)
0° to 125°C
SC1173CSW SO-24
Adj. 0° to 125°C
Note:
(1) Add suffix ‘TR’ for tape and reel.
PIN CONFIGURATION
BLOCK DIAGRAM
Top View
AGND
1
NC
2
NC
3
LDOS
4
VCC
5
OVP
6
PWRGOOD
7
CS-
8
CS+
9
PGNDH
10
DH
11
PGNDL
12
24
GATE
23
LDOV
22
VID0
21
VID1
20
VID2
19
VID3
18
VID4
17
VOSENSE
16
EN
15
BSTH
14
BSTL
13
DL
(24 Pin SOIC)
VCC CS- CS+
EN
VID4
VID3
VID2
VID1
VID0
1.25 REF
VCC
D/A &
SHUT-
DOWN
LOGIC
70mV
CURRENT LIMIT
OSCILLATOR
R
Q
S
BSTH
LEVEL SHIFT
AND HIGH SIDE
DH
MOSFET DRIVE
PGNDH
VOSENSE
PWRGOOD
OPEN
COLLECTORS
VCC
ERROR
AMP
OVP
AGND
1.25V
REF
SHOOT-
THRU
CONTROL
SYNCHRONOUS
MOSFET DRIVER
BSTL
DL
FET
CONTROLLER
PGNDL
LDOV
GATE LDOS
© 1999 SEMTECH CORP.
Pentium is a registered trademark of Intel Corporation
1
652 MITCHELL ROAD NEWBURY PARK CA 91320