SC1185 Datasheet, PDF (1/12 Pages) Semtech Corporation – PROGRAMMABLE SYNCHRONOUS DC/DC CONVERTER, DUAL LOW DROPOUT REGULATOR CONTROLLER

PRELIMINARY - January 6, 1999
PROGRAMMABLE SYNCHRONOUS DC/DC
CONVERTER, DUAL LOW DROPOUT
REGULATOR CONTROLLER
SC1185
SC1185A
TEL:[phone] FAX:[phone] WEB:http://www.semtech.com
DESCRIPTION
The SC1185 combines a synchronous voltage mode
controller with two low-dropout linear regulators
providing most of the circuitry necessary to
implement three DC/DC converters for powering
advanced microprocessors such as Pentium^® II .
The SC1185 switching section features an integrated
5 bit D/A converter, pulse by pulse current limiting,
integrated power good signaling, and logic compatible
shutdown. The SC1185 switching section operates at
a fixed frequency of 140kHz, 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 compo-
nents.
The SC1185 linear sections are low dropout regula-
tors supplying 1.5V for GTL bus and 2.5V for non-
GTL I/O. The Reference voltage is made available for
external linear regulators.
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^® ll requirements
• 1.5V, 2.5V @ 1% for linear section
• 1.265V ± 1.5% Reference available
APPLICATIONS
• Pentium^® ll microprocessor supplies
• Flexible motherboards
• 1.3V to 3.5V microprocessor supplies
• Programmable triple power supplies
ORDERING INFORMATION
Part Number⁽¹⁾
Package
Linear
Voltage
Temp.
Range (T_J)
SC1185CSW
SO-24 1.5V/2.5V 0° to 125°C
SC1185ACSW⁽²⁾ SO-24 1.5V/2.5V 0° to 125°C
Note:
(1) Add suffix ‘TR’ for tape and reel.
(2) SC1185A provides improved output tolerance. See
Output Voltage Table.
PIN CONFIGURATION
Top View
AGND
1
GATE1
2
LDOS1
3
LDOS2
4
VCC
5
REF
6
PWRGOOD
7
CS-
8
CS+
9
PGNDH 10
DH 11
PGNDL 12
24
GATE2
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)
BLOCK DIAGRAM
VCC CS- CS+
VID4
VID3
VID2
VID1
VID0
VOSENSE
PWRGOOD
REF.
D/A
LDOS1
GATE1
FET
CONTROLLER
2.5V/ADJ.
1.265V
REF.
EN
FET
CONTROLLER
1.5V/ADJ.
BSTH
DH
PGNDH
BSTL
DL
PGNDL
LDOV
REF
GATE2 LDOS2 AGND
© 1999 SEMTECH CORP.
Pentium is a registered trademark of Intel Corporation
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