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PDF SC1172 Data sheet ( Hoja de datos )
| Número de pieza | SC1172 | |
| Descripción | Programmable Synchronous DC/DC Converter | |
| Fabricantes | Semtech Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SC1172 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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POWER MANAGEMENT
Description
SC1172 & SC1173
Programmable Synchronous DC/DC
Converter with LDO Controller
Features
The SC1172/3 combines a synchronous voltage mode con-
troller with a low-dropout linear regulator providing most
of the circuitry necessary to implement two DC/DC con-
verters for powering advanced microprocessors such as
Pentium® II .
The SC1172/3 switching section features an integrated 5
bit D/A converter, pulse by pulse current limiting, inte-
grated power good signaling, and logic compatible shut-
down. The SC1172/3 switching section operates at a fixed
frequency of 200kHz, providing an optimum compromise
between size, efficiency and cost in the intended applica-
tion areas. The integrated D/A converter provides pro-
grammability 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 low dropout regulator.
The SC1172 supplies 1.5V for GTL bus , the SC1173 fea-
tures an adjustable LDO voltage.
u Synchronous design, enables no heatsink solution.
u 95% efficiency (switching section).
u 5 bit DAC for output programmability.
u On chip power good function.
u Designed for Intel Pentium® ll VRM8.1 requirements.
u 1.5V or Adjustable @ 1% for linear section.
Applications
u Pentium® ll microprocessor supplies
u Flexible motherboards
u 1.3V to 3.5V microprocessor supplies
u Programmable triple power supplies
Typical Application Circuit
12V
5V
+
1500uF
x2
PWRGOOD
VID0
VID1
VID2
VID3
VID4
EN
3.3V
10
0.1uF
U4
5 VCC
7 PWRGOOD
CS+ 9
CS- 8 0.1uF
22 VID0
VOSENSE 17
IRLR3103N
21 VID1
20 VID2
BSTH
DH
15
11
2R2
19 VID3
BSTL 14
IRLR3103N
18 VID4
16 EN
DL
PGNDH
13
10
2R2
1 AGND
PGNDL 12
23 LDOV
OVP 6
24 GATE
NC 2
4 LDOS
NC 3
SC1172/3CSW
0.1uF
+
4.7uF
1.9uH
OVP
1.00k
2.32k
5mOhm
VCC_CORE
+
1500uF
x4
0.1uF
330uF
+
IRLR024N
+
330uF
1.5V
Revision 1, January 2001
1
www.semtech.com
1 page  
POWER MANAGEMENT
Block Diagram
SC1172 & SC1173
CS- CS+
VCC
EN
VID4
VID3
VID2
VID1
VID0
VOSENSE
PWRGOOD
OVP
REF
D/A
+
-
OPEN
COLLECTORS
+
VCC
-
+
-
70mV
+
-
CURRENT LIMIT
OSCILLATOR
R
Q
S
+
-
ERROR
AMP
-
+
AGND
1.265V
REF
FET
CONTROLLER
1.5V/ADJ.
LEVEL SHIFT
AND HIGH SIDE
DRIVE
SHOOT
THRU
CONTROL
BSTH
DH
PGNDH
SYNCHRONOUS
DRIVE
BSTL
DL
PGNDL
AGND
LDOV
GATE LDOS AGND
Setting LDO Output Voltage.
For the SC1173, the LDO Output voltage must be set by
selecting appropriate resistor values. These values may be
determined from the equation below, or from the table at
right.
VOUT
=
1.265 ⋅ (RA
RB
+ RB ) + (IFB
⋅RA)
where :
IFB = Feedback pin bias current
RA = Top feedback resistor
RB = Bottom feedback resistor
See layout diagram for clarification
RA must be low enough so that the (IFB ⋅ RA ) term
does not cause significant error
VOUT LDO
3.45V
3.30V
3.10V
2.90V
2.80V
2.50V
1.50V
© 2001 Semtech Corp.
5
RB RA
105Ω
105Ω
102Ω
100Ω
100Ω
100Ω
100Ω
182Ω
169Ω
147Ω
130Ω
121Ω
97.6Ω
18.7Ω
www.semtech.com
5 Page 
POWER MANAGEMENT
Typical Characteristics
Typical Efficiency at Vo=3.5V
95%
90%
85%
80%
75%
3.5V Std
3.5V Sync
3.5V Sync Lo Rds
70%
0 2 4 6 8 10 12 14 16
Io (Am ps)
95%
90%
85%
80%
75%
70%
0
Typical Efficiency at Vo=2.5V
2.5V Std
2.5V Sync
2.5V Sync Lo Rds
2 4 6 8 10 12 14 16
Io (Amps)
Typical Ripple, Vo=2.8V, Io=10A
SC1172 & SC1173
95%
90%
85%
80%
75%
70%
0
Typical Efficiency at Vo=2.8V
2.8V Std
2.8V Sync
2.8V Sync Lo Rds
2 4 6 8 10 12 14 16
Io (Am ps)
95%
90%
85%
80%
75%
70%
0
Typical Efficiency at Vo=2.0V
2.0V Std
2.0V Sync
2.0V Sync Lo Rds
2 4 6 8 10 12 14 16
Io (Am ps)
Transient Response Vo=2.8V, Io=300mA to 10A
© 2001 Semtech Corp.
11
www.semtech.com
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet SC1172.PDF ] | |
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