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SC1102
SYNCHRONOUS DC/DC CONTROLLER FOR
DISTRIBUTED POWER SUPPLY APPLICATIONS
2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
September 5, 2000
1
DESCRIPTION
The SC1102 is a low-cost, full featured, synchronous
voltage-mode controller designed for use in single
ended power supply applications where efficiency is of
primary concern. Synchronous operation allows for the
elimination of heat sinks in many applications. The
SC1102 is ideal for implementing DC/DC converters
needed to power advanced microprocessors in low
cost systems, or in distributed power applications
where efficiency is important. Internal level-shift, high-
side drive circuitry, and preset shoot-thru control, al-
lows the use of inexpensive N-channel power switches.
SC1102 features include temperature compensated
voltage reference, triangle wave oscillator and current
sense comparator circuitry. Power good signaling,
shutdown, and over voltage protection are also pro-
vided.
The SC1102 operates at a fixed 200kHz, providing an
optimum compromise between efficiency, external
component size, and cost.
FEATURES
1.265V Reference available
Synchronous operation
Over current fault monitor
On-chip power good and OVP functions
Small size with minimum external components
Soft Start
R
DS(ON)
Current sensing
APPLICATIONS
Microprocessor core supply
Low cost synchronous applications
Voltage Regulator Modules (VRM)
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DEVICE
(1)
PACKAGE
TEMP. RANGE (T
J
)
SC1102CSTR
SO-14
0 - 125C
SC1102EVB
Evaluation Board
ORDERING INFORMATION
Note:
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
APPLICATION CIRCUIT
Figure 1.
Typical Distributed Power Supply
VCC
1
PWRGD
2
OVP
3
OCSET
4
PHASE
5
DRVH
6
PGND
7
DRVL
8
BSTL
9
BSTH
10
SENSE
11
VREF
12
SS/SHDN
13
GND
14
U1
SC1102
Q1
STP40NE
Q2
STP40NE
R5
3.9
L1
2uH
C9
180/4V
C10
180/4V
C11
180/4V
C12
180/4V
C7
680/6.3V
C6
680/6.3V
R1
1k
R3
1k
C2
0.1
C3
0.1
C1
0.1
R2
PWRGD
OVP
SHDN
VREF
+
_
+
_
Vin 5V
Vout=2.5V*
R7
127
R8
124*
NOTE:
*) Vout = 1.265 x (1+R8/R7)
+5V
D1
MBR0520
R6
2.2
C4
1.0
C5
10.0
C8
680/6.3V
R4
10
+12V
C13
180/4V
SC1102
SYNCHRONOUS DC/DC CONTROLLER FOR
DISTRIBUTED POWER SUPPLY APPLICATIONS
2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
September 5, 2000
2
NOTE:
(1) Specification refers to application circuit (Figure 1).
ELECTRICAL CHARACTERISTICS
Unless specified: V
CC
= 4.75V to 12.6V; GND = PGND = 0V; FB = V
O
; V
BSTL
= 12V; V
BSTH-PHASE
= 12V; T
J
= 25
o
C
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLY
Supply Voltage
V
CC
4.2
12.6
V
Supply Current
EN = V
CC
6
10
mA
Line Regulation
V
O
= 2.5V
0.5
%
ERROR AMPLIFIER
Gain (AOL)
35
dB
Input Bias
5
8
A
OSCILLATOR
Oscillator Frequency
180
200
220
kHz
Oscillator Max Duty Cycle
90
95
%
MOSFET DRIVERS
DH Source/Sink Current
BST
H
- DH = 4.5V / DH - PHASE = 2V
1
A
DL Source/Sink Current
BST
L
- DL = 4.5V / DL - PGND
L
= 2V
1
A
PROTECTION
OVP Threshold Voltage
20
%
OVP Source Current
V
OVP
= 3V
10
mA
Power Good Threshold
88
112
%
Dead Time
45
100
ns
Over Current Set Isource
2.0V
V
OCSET
12V
180
200
220
A
ABSOLUTE MAXIMUM RATINGS
Parameter
Symbol
Maximum
Units
V
CC
, BSTL to GND
V
IN
-0.3 to 14
V
PGND to GND
0.5
V
PHASE to GND
-0.3 to 18
V
BSTH to PHASE
14
V
Thermal Resistance Junction to Case
JC
45
C/W
Thermal Resistance Junction to Ambient
JA
115
C/W
Operating Temperature Range
T
A
0 to 70
C
Storage Temperature Range
T
STG
-65 to +150
C
Lead Temperature (Soldering) 10 sec
T
LEAD
300
C
ESD Rating (Human Body Model)
ESD
2
kV
SC1102
SYNCHRONOUS DC/DC CONTROLLER FOR
DISTRIBUTED POWER SUPPLY APPLICATIONS
2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
September 5, 2000
3
ELECTRICAL CHARACTERISTICS (CONT)
Unless specified: V
CC
= 4.75V to 12.6V; GND = PGND = 0V; FB = V
O
; V
BSTL
= 12V; V
BSTH-PHASE
= 12V; T
J
= 25
o
C
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
Reference Voltage
1.252
1.265
1.278
V
Accuracy
-1
+1
%
SOFT START
Charge Current
V
SS
= 1.5V
8.0
10
12
A
Discharge Current
V
SS
= 1.5V
1.3
2
2.4
A
BLOCK DIAGRAM
PIN CONFIGURATION
Top View
(14-Pin SOIC)
SC1102
SYNCHRONOUS DC/DC CONTROLLER FOR
DISTRIBUTED POWER SUPPLY APPLICATIONS
2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
September 5, 2000
4
NOTE:
(1) All logic level inputs and outputs are open collector TTL compatible.
PIN DESCRIPTION
Pin #
Pin Name
Pin Function
1
VCC
Chip supply voltage
2
PWRGD
Logic high indicates correct output voltage
3
OVP
Over voltage protection.
4
OCSET
Sets the converter overcurrent trip point
5
PHASE
Input from the phase node between the MOSFET'S
6
DH
High side driver output
7
PGND
Power ground
8
DL
Low side driver output
9
BSTL
Bootstrap, low side driver.
10
BSTH
Bootstrap, high side driver.
11
SENSE
Voltage sense input
12
VREF
Buffered band gap voltage reference.
13
SS/SHDN
Soft start. A capacitor to ground sets the slow start time.
14
GND
Signal ground
CHARACTERISTIC CURVES
SC1102 Voltage Regulation, Vin=5V
-2%
-1%
0%
1%
2%
0
1
2
3
4
5
6
7
8
9
10 11 12
Current, A
3.3V
2.5V
2.0V
1.3V
SC1102 Effiency, Vin=5V
60%
70%
80%
90%
100%
0
1
2
3
4
5
6
7
8
9
10
11
12
Current, A
3.3V
2.5V
2.0V
1.3V
SC1102
SYNCHRONOUS DC/DC CONTROLLER FOR
DISTRIBUTED POWER SUPPLY APPLICATIONS
2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
September 5, 2000
5
Gate Drive Waveforms
Output Ripple Voltage
Ch1: Top FET
Ch2: Bottom FET
Ch1: Vo_rpl
Ch1: Vo_rpl
Ch1: Top FET
Ch2: Bottom FET
1. V
IN
= 5V; V
O
= 3.3V; I
OUT
= 12A
2. V
IN
= 5V; V
OUT
= 1.3V; I
OUT
= 12A
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