LT1372/LT1377
500kHz and 1MHz
High Efficiency
1.5A Switching Regulators
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
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 12µA. 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Boost Regulators
CCFL Backlight Driver
Laptop Computer Supplies
Multiple Output Flyback Supplies
Inverting Supplies
TYPICAL APPLICATIO
5V-to-12V Boost Converter
5V
5
OFF
ON 4 S/S
V
IN
V
SW
8
L1*
4.7µH
D1
MBRS120T3
V
OUT
12V
R1
53.6k
1%
100
†
EFFICIENCY (%)
LT1372/LT1377
+
C1**
22µF
FB
GND
6, 7
C2
0.047µF
R3
2k
V
C
1
2
+
R2
6.19k
1%
C3
0.0047µF
C4**
22µF
*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
†
MAX I
OUT
L1 I
OUT
(LT1377) I
OUT
(LT1372)
0.25A
NA
4.7µH
0.35A
0.29A
10µH
LT1372 • TA01
U
12V Output Efficiency
V
IN
= 5V
90
80
70
60
50
0.01
0.1
OUTPUT CURRENT (A)
1
LT1372 • TA02
U
U
1
LINER [ LINEAR TECHNOLOGY ]
