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1
LT1372/LT1377
500kHz and 1MHz
High Efficiency
1.5A Switching Regulators
s
Boost Regulators
s
CCFL Backlight Driver
s
Laptop Computer Supplies
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Multiple Output Flyback Supplies
s
Inverting Supplies
The LT
1372/LT1377 are monolithic high frequency
switching regulators. They can be operated in all standard
switching configurations including boost, buck, flyback,
forward, inverting and “Cuk.” A 1.5A high efficiency switch
is included on the die, along with all oscillator, control and
protection circuitry. All functions of the LT1372/LT1377
are integrated into 8-pin SO/PDIP packages.
The LT1372/LT1377 typically consumes only 4mA quies-
cent current and has higher efficiency than previous parts.
High frequency switching allows for very small inductors
to be used. All surface mount components consume less
than 0.5 square inch of board space.
New design techniques increase flexibility and maintain
ease of use. Switching is easily synchronized to an exter-
nal logic level source. A logic low on the shutdown pin
reduces supply current to 12
A. Unique error amplifier
circuitry can regulate positive or negative output voltage
while maintaining simple frequency compensation tech-
niques. Nonlinear error amplifier transconductance re-
duces output overshoot on start-up or overload recovery.
Oscillator frequency shifting protects external compo-
nents during overload conditions.
s
Faster Switching with Increased Efficiency
s
Uses Small Inductors: 4.7
H
s
All Surface Mount Components
s
Only 0.5 Square Inch of Board Space
s
Low Minimum Supply Voltage: 2.7V
s
Quiescent Current: 4mA Typ
s
Current Limited Power Switch: 1.5A
s
Regulates Positive or Negative Outputs
s
Shutdown Supply Current: 12
A Typ
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Easy External Synchronization
s
8-Pin SO or PDIP Packages
, LTC and LT are registered trademarks of Linear Technology Corporation.
12V Output Efficiency
OUTPUT CURRENT (A)
0.01
50
EFFICIENCY
(%)
60
70
80
90
0.1
1
LT1372 TA02
100
VIN = 5V
5V-to-12V Boost Converter
LT1372/LT1377
VIN
VC
5V
1
2
8
5
4
6, 7
GND
FB
LT1372 TA01
VSW
S/S
L1*
4.7
H
C1**
22
F
C4**
22
F
C2
0.047
F
C3
0.0047
F
R3
2k
R2
6.19k
1%
R1
53.6k
1%
VOUT
12V
D1
MBRS120T3
ON
OFF
*FOR LT1372 USE 10
H
COILCRAFT DO1608-472 (4.7
H) OR
COILCRAFT DT3316-103 (10
H) OR
SUMIDA CD43-4R7 (4.7
H) OR
SUMIDA CD73-100KC (10
H) OR
**AVX TPSD226M025R0200
L1
4.7
H
10
H
IOUT (LT1377)
0.25A
0.35A
IOUT (LT1372)
NA
0.29A
MAX IOUT
+
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U