SC1185CSW Semtech Corporation, SC1185CSW Datasheet

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SC1185CSW

Manufacturer Part Number
SC1185CSW
Description
Manufacturer
Semtech Corporation
Datasheet

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Part Number:
SC1185CSW
Manufacturer:
SEMTECH
Quantity:
402
PRELIMINARY - January 6, 1999
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
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.
PIN CONFIGURATION
© 1999 SEMTECH CORP.
PWRGOOD
PGNDH
PGNDL
GATE1
LDOS1
LDOS2
AGND
VCC
REF
CS+
CS-
DH
(24 Pin SOIC)
10
11
12
Top View
1
2
3
4
5
6
7
8
9
24
23
22
21
20
19
18
17
16
15
14
13
GATE2
LDOV
VID0
VID1
VID2
VID3
VID4
VOSENSE
EN
BSTH
BSTL
DL
BLOCK DIAGRAM
PWRGOOD
VOSENSE
PROGRAMMABLE SYNCHRONOUS DC/DC
CONVERTER, DUAL LOW DROPOUT
REGULATOR CONTROLLER
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
®
LDOS1
GATE1
II .
VID4
VID3
VID2
VID1
VID0
REF.
D/A
CONTROLLER
2.5V/ADJ.
VCC
FET
FEATURES
APPLICATIONS
ORDERING INFORMATION
SC1185CSW
SC1185ACSW
Note:
(1) Add suffix ‘TR’ for tape and reel.
(2) SC1185A provides improved output tolerance. See
Output Voltage Table.
Part Number
652 MITCHELL ROAD NEWBURY PARK CA 91320
CS- CS+
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
1.5V, 2.5V @ 1% for linear section
1.265V ± 1.5% Reference available
Pentium
Flexible motherboards
1.3V to 3.5V microprocessor supplies
Programmable triple power supplies
LDOV
1.265V
REF.
®
ll microprocessor supplies
(1)
(2)
Pentium is a registered trademark of Intel Corporation
REF
Package
SO-24
SO-24
CONTROLLER
1.5V/ADJ.
FET
EN
®
1.5V/2.5V 0° to 125°C
1.5V/2.5V 0° to 125°C
ll requirements
GATE2
Voltage
Linear
LDOS2
SC1185A
AGND
SC1185
Range (T
Temp.
BSTH
DH
PGNDH
BSTL
DL
PGNDL
1
J
)

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SC1185CSW Summary of contents

Page 1

... Pentium ll microprocessor supplies Flexible motherboards 1.3V to 3.5V microprocessor supplies Programmable triple power supplies ORDERING INFORMATION (1) Part Number SC1185CSW (2) SC1185ACSW Note: (1) Add suffix ‘TR’ for tape and reel. (2) SC1185A provides improved output tolerance. See Output Voltage Table. BLOCK DIAGRAM VCC CS- CS+ REF ...

Page 2

PRELIMINARY - January 6, 1999 ABSOLUTE MAXIMUM RATINGS Parameter VCC to GND PGND to GND BST to GND Operating Temperature Range Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering) 10 seconds Thermal Impedance Junction to Ambient Thermal Impedance Junction ...

Page 3

PRELIMINARY - January 6, 1999 PIN DESCRIPTION Pin Pin Name Pin Function 1 AGND Small Signal Analog and Digital Ground 2 GATE1 Gate Drive Output LDO1 3 LDOS1 Sense Input for LDO1 4 LDOS2 Sense Input for LDO2 5 VCC ...

Page 4

PRELIMINARY - January 6, 1999 OUTPUT VOLTAGE Unless specified: 4.75V < VCC < 5.25V; GND = PGND = 0V; VOSENSE = V PARAMETER VID 43210 Output Voltage 01111 01110 01101 01100 01011 01010 01001 01000 00111 00110 00101 00100 00011 ...

Page 5

PRELIMINARY - January 6, 1999 APPLICATION CIRCUIT © 1999 SEMTECH CORP. PROGRAMMABLE SYNCHRONOUS DC/DC CONVERTER, DUAL LOW DROPOUT REGULATOR CONTROLLER 652 MITCHELL ROAD NEWBURY PARK CA 91320 SC1185 SC1185A 5 ...

Page 6

... 2.32k , 1%, 1/ 1%, 1/ 5%, 1/ SC1185CSW © 1999 SEMTECH CORP. PROGRAMMABLE SYNCHRONOUS DC/DC CONVERTER, DUAL LOW DROPOUT REGULATOR CONTROLLER Vendor Notes Various SANYO MV-GX or equiv. Low ESR Various 8 Turns 16AWG on MICROMETALS T50-52D core See notes FET selection requires trade-off between efficiency and cost ...

Page 7

PRELIMINARY - January 6, 1999 95% 90% 85% 80% 3.5V Std 3.5V Sync 3.5V Sync Lo Rds 75% 70 (Amps) Typical Efficiency at Vo=3.5V 95% 90% 85% 80% 2.5V Std 2.5V Sync 2.5V Sync ...

Page 8

PRELIMINARY - January 6, 1999 LAYOUT GUIDELINES Careful attention to layout requirements are necessary for successful implementation of the SC1185 PWM controller. High currents switching at 140kHz are pre- sent in the application and their effect on ground plane voltage ...

Page 9

PRELIMINARY - January 6, 1999 4) The Output Capacitor(s) (Cout) should be located as close to the load as possible, fast transient load currents are supplied by Cout only, and connections between Cout and the load must be short, wide ...

Page 10

PRELIMINARY - January 6, 1999 COMPONENT SELECTION SWITCHING SECTION OUTPUT CAPACITORS - Selection begins with the most critical component. Because of fast transient load current requirements in modern microprocessor core supplies, the output capacitors must supply all transient load current ...

Page 11

PRELIMINARY - January 6, 1999 Using 1.5X Room temp R to allow for temperature DS(ON) rise. FET type ( ( DS(on) IRL34025 15 1.69 IRL2203 10.5 1.19 Si4410 20 2.26 BOTTOM FET - Bottom FET losses ...

Page 12

PRELIMINARY - January 6, 1999 OUTLINE DRAWING © 1999 SEMTECH CORP. PROGRAMMABLE SYNCHRONOUS DC/DC CONVERTER, DUAL LOW DROPOUT REGULATOR CONTROLLER 652 MITCHELL ROAD NEWBURY PARK CA 91320 SC1185 SC1185A JEDEC MS-013AD B17104B 12 ...

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