LIN D
O C
#:
2172
LX2172/73
1.25A H
IGH
-E
FFICIENCY
100
K
H
Z
S
WITCHING
R
EGULATOR
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O VA T I O N
P
R E L I M I N A R Y
D
A T A
S
H E E T
DESCRIPTION
The LX2172/73 are fixed-frequency, cur-
rent-mode switching regulator integrated
circuits. These ICs contain all necessary
control circuitry plus a 1.25A on-board
transistor to design a complete DC:DC
switching regulator with minimum exter-
nal components.
All functions are integrated into a single
IC, available in 8-pin DIP and SOIC or a
5-pin TO-220 power package, making
them extremely easy to design with and
use. The LX2172/73 are optimized for
boost and flyback applications, but can
also be used in forward and inverting
converter configuations.
The LX2172 can be connected to an
external clock for synchronization, and
can enter micropower operation when
the V
C
pin is pulled low. The LX2173
has an enable function, which permits
extremely low micropower operation,
consuming under 10碌A(chǔ) current when the
ENABLE pin is brought low.
K E Y F E AT U R E S
s
1.25A, 65V Internal Power Switch
s
3V - 25V Input Voltage Range
s
Current-Mode Operation
s
Improved Internal Cycle-By-Cycle Current
Limiting
s
Thermal Shutdown
s
Less Than 10碌A(chǔ) Quiescent Current In
Microprocessor Shutdown Mode
s
External Frequency Synchronization
Possible
s
100kHz Operating Frequency
NOTE:
For current data & package dimensions, visit our web site:
http://www.linfinity.com.
A P P L I C AT I O N S
s
Boost Converter
s
Laptop / Notebook Computers
s
Portable Equipment
s
Small Motor Applications
s
Flyback Converters
PRODUCT HIGHLIGHT
SEPIC C
ONVERTER
U
SING
T
H E
LX2172
Input 6-24V, Output 7V, 300mA
V
IN
6-24V
DC
L1
C
1
22碌F
R
1
13.7k
C
4
0.47碌F
C
3
0.1碌F
U1
1
2
3
4
C
2
330碌F
D1
1N5817
C
OUT
220碌F
Output
7V
300mA
7V
A
VA I L A B L E
O
P T I O N S
Part #
LX2172
LX2173
PER
P
AR T
#
1mH
8
7
6
5
Pin 4
Connections
SYNC Input
Low 碌Power Mode
GND
E
2
(HI ENABLE)
LX2172
V
C
FB
SYNC
V
SW
E
1
V
IN
= Samples Not Yet Available.
L2
1mH
(See Note 1)
C
DECOUPLE
0.47碌F
R
2
3.0k
R
3
100
Note 1: SYNC Pin Requirements:
A) F
MAX
= 200kHz
B) TTL Compatible Level
C) Pulse Width T
P
Range - 0.1碌s < T
P
< 2.0碌s
PA C K A G E O R D E R I N F O R M AT I O N
T
A
(擄C)
0 to 70
M
Plastic DIP
8-pin
LX217xCM
DM
Plastic SOIC
8-pin
LX217xCDM
P
Plastic TO-220
5-pin
LX217xCP
Note: All surface-mount packages are available in Tape & Reel.
Append the letter "T" to part number. (i.e. LX217xCDMT)
Copyright 漏 1998
Rev. 0.4 12/98
L
IN
F
INITY
M
ICROELECTRONICS
I
NC
.
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841, 714-898-8121, F
AX
: 714-893-2570
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