Combination Switching Controller
and Low Dropout Regulator
POWER MANAGEMENT
Description
The SC1131/2/3/4 incorporates a high current low
dropout linear regulator section together with a
switching voltage-mode controller. This unique combina-
tion is well suited for high current low voltage power sup-
ply applications such as the Intel Pentium
TM
P55, AMD
K6 and the Cyrix M2 processors. The SC113X was de-
signed to reduce the number of components required to
design a dual power supply for multivoltage processor
applications.
Switching Controller Section:
The switching control
section is a voltage mode controller designed for high
current, low voltage power supply applications. Key
features include a temperature compensated voltage
reference, triangular oscillator and an internally
compensated transconductance error amplifier. The
switching controller operates at a fixed frequency of
200kHz, providing an optimum compromise between
size, efficiency and cost in the intended application
areas.
Linear Section:
The linear portion is a high performance
positive voltage regulator designed for use in
applications requiring very low dropout performance
at 1.5, 3, 5 and 7.5 Amps. Additionally, the linear
section provides excellent regulation over variations due
to changes in line, load or temperature.
SC113X
Features
u
u
u
u
u
u
85% typical efficiency for switching section
Grounded tab
1.5, 2.5 or 3.3V @ 1% for linear section
Thermal shutdown
Internal short circuit protection (LDO)
7 pin TO-220 package
Applications
u
u
u
u
Microprocessor supplies
Modules supplies
1.3V to 3.5V power supplies
Dual power supplies from 5V source
Typical Application Circuit
5VIN
Q1
BUK556
L1
4uH
Vout (SW)
+
C1
0.1uF
+
C2
1000uF
C3
1000uF
C4
1000uF
+
R3
2.7
R1
D1
C5
1000uF
+
C6
1000uF
+
C7
1000uF
+
C8
1000uF
+
R2
C10
0.01uF
C9
1000uF
+
Vout (LIN)
SC1133
12V IN
C11
0.1uF
Revision 1, December 2000
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SC113X
POWER MANAGEMENT
Absolute Maximum Ratings
V
IN
to GND
V
CC
to GND
Operati ng Temperature
Juncti on Operati ng Temperature
Storage Temperature
Lead Solderi ng Temperature
Thermal Resi stance, Juncti on to
C a se
Thermal Resi stance, Juncti on to
Ambi ent
T
A
T
J
T
S
T
L
q
JC
q
JA
-0.3V, 7V
-0.3V, 15V
0°C to +70°C
0°C to +125°C
-65°C to +125°C
260°C , 10 sec.
2°C /W
50°C /W
Electrical Characteristics
Switching Control Section
V
CC
= 12V; V
IN
= 5.0V; GND = P
GND
= 0V; V
OUT
= 2.8V. Per application circuit unless otherwise specifi
Sy mbol
I
CC
V
REF
Parameter
Total Qui escent C urrent
Reference Voltage
C onditions
Li near out =No Load
Temp
25°C
25°C
0-125°C
Min
Ty p
15
Max
25
1.263
1.275
1
U nits
mA
V
1.238
1.225
1.250
1.250
Reg
LOAD
Reg
LINE
D H
HI
D H
LOW
f
OSC
dc
Load Regulati on
Li ne Regulati on
MOSFET D ri ver
Source Voltage
MOSFET D ri ver Si nk
Voltage
Osci llator Frequency
D uty C ycle (maxi mum)
V
CC
- D H; I
DH
= 0.5A
D H-P
GND
; I
DH
= 0.5A
25°C
25°C
25°C
25°C
25°C
25°C
180
90
0.5
1.6
1.1
200
95
%
%
V
V
220
kHz
%
ã
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SC113X
POWER MANAGEMENT
Pin Configuration
Ordering Information
Part N umber
(1)
SC113X
P ackag e
TO-220
TO-220
TO-220
TO-220
Output C urrent
1.5A
3.0A
5.0A
7.5A
SC 1131C T-XY
SC 1132C T-XY
SC 1133C T-XY
12 34 56 7
SC 1134C T-XY
Pin #
1
2
3
4
5
6
7
Pin N ame
DH
P
GND
Vo
SENSE
GND
V
CC
V
OUT
V
IN
Function
MOSFET D ri ver Output
Swi tchi ng Power Ground
Error Ampli fi er Input (Swi tcher)
Si gnal Ground
+12V Input Voltage
V
OUT
(Li nerar Secti on)
+5V Input Voltage
Note:
(1) Where XY denotes voltage options and lead con-
figurations. Available voltages (X) are: 1.5V, 2.5V and
3.3V. Available lead configurations (Y) are dual bend (DB),
single bend (SB) and straight leads (leave blank).
Sample part number: SC1133CT-2.5DB.
Block Diagram
Vcc
(5)
Vin
(7)
1.25V REF
-
+
CONTROL
CURRENT LIMIT
+
-
OSCILLATOR
THERMAL OVERLOAD
Vout
(6)
-
+
+
LEVEL SHIFT
AND DRIVE
DH
(1)
Vo Sense
(3)
-
ERROR
AMP
PGND
GND
(4)
(2)
ã
2000 Semtech Corp.
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SC113X
POWER MANAGEMENT
Typical Characteristics
SC113x Efficiency
95
% Load Regulation 3.3V, 0.3 to 10 Amps
1.0
0.5
90
% Efficiency
PIN Descriptions
85
3.3
2.9
2.5
1.8
0.0
-0.5
80
-1.0
75
-1.5
70
0
2
4
6
8
10
-2.0
0
2
4
6
8
10
Load Current (A)
Load Current (A)
% Load Regulation 2.9V, 0.3 to 10 Amps
1.0
% Load Regulation 2.3V, 0.2 to 10 Amps
1.0
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
-1.0
-1.5
-1.5
-2.0
0
2
4
6
8
10
-2.0
0
2
4
6
8
10
Load Current (A)
Load Current (A)
% Load Regulation 1.8V, 0.2 to 10 Amps
1.0
0.5
Transient Load Current Rise 3.3V @ 10A
0.0
-0.5
-1.0
-1.5
-2.0
0
2
4
6
8
10
Load Current (A)
ã
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