LT1372/LT1377
500kHz and 1MHz
High Efficiency
1.5A Switching Regulators
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FEATURES
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DESCRIPTIO
Faster Switching with Increased Efficiency
Uses Small Inductors: 4.7µH
All Surface Mount Components
Only 0.5 Square Inch of Board Space
Low Minimum Supply Voltage: 2.7V
Quiescent Current: 4mA Typ
Current Limited Power Switch: 1.5A
Regulates Positive or Negative Outputs
Shutdown Supply Current: 12µA Typ
Easy External Synchronization
8-Pin SO or PDIP Packages
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APPLICATIO S
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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 quiescent 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 external logic level source. A logic low on the shutdown pin
reduces supply current to 12µA. Unique error amplifier
circuitry can regulate positive or negative output voltage
while maintaining simple frequency compensation techniques. Nonlinear error amplifier transconductance reduces output overshoot on start-up or overload recovery.
Oscillator frequency shifting protects external components during overload conditions.
Boost Regulators
CCFL Backlight Driver
Laptop Computer Supplies
Multiple Output Flyback Supplies
Inverting Supplies
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
12V Output Efficiency
5V-to-12V Boost Converter
OFF
5
VIN
ON 4 S/S
VSW
LT1372/LT1377
+
C1**
22µF
FB
GND
6, 7
C2
0.047µF
R3
2k
100
D1
MBRS120T3
L1*
4.7µH
VOUT†
12V
R1
53.6k
1%
8
2
+
VC
R2
6.19k
1%
1
C3
0.0047µF
C4**
22µF
VIN = 5V
90
*FOR LT1372 USE 10µH
COILCRAFT DO1608-472 (4.7µH) OR
COILCRAFT DT3316-103 (10µH) OR
SUMIDA CD43-4R7 (4.7µH) OR
SUMIDA CD73-100KC (10µH) OR
**AVX TPSD226M025R0200
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MAX IOUT
L1 IOUT (LT1377) IOUT (LT1372)
0.25A
NA
4.7µH
0.35A
0.29A
10µH
LT1372 • TA01
EFFICIENCY (%)
5V
80
70
60
50
0.01
0.1
OUTPUT CURRENT (A)
1
LT1372 • TA02
1
