LT1371
500kHz High Efficiency
3A Switching Regulator
FEATURES
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DESCRIPTION
The LT
®
1371 is a monolithic high frequency current mode
switching regulator. It can be operated in all standard
switching configurations including boost, buck, flyback,
forward, inverting and “Cuk.” A 3A high efficiency switch
is included on the die, along with all oscillator, control and
protection circuitry.
The LT1371 typically consumes only 4mA quiescent
current and has higher efficiency than previous parts.
High frequency switching allows for very small inductors
to be used.
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.
Faster Switching with Increased Efficiency
Uses Small Inductors: 4.7µH
All Surface Mount Components
Low Minimum Supply Voltage: 2.7V
Quiescent Current: 4mA Typ
Current Limited Power Switch: 3A
Regulates Positive or Negative Outputs
Shutdown Supply Current: 12µA Typ
Easy External Synchronization
APPLICATIONS
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Boost Regulators
Laptop Computer Supplies
Multiple Output Flyback Supplies
Inverting Supplies
TYPICAL APPLICATION
5V to 12V Boost Converter
5V
L1*
4.7µH
D1
MBRS330T3
V
OUT
12V
R1
53.6k
1%
†
V
IN
OFF
ON
S/S
LT1371
V
SW
EFFICIENCY (%)
+
C1**
22µF
25V
FB
GND
C2
0.047µF
R3
2k
V
C
+
R2
6.19k
1%
C3
0.0047µF
LT1371 • TA01
C4**
22µF
25V
×
2
*COILCRAFT DO3316P-472 (4.7µH),
DO3316P-103 (10µH) OR
SUMIDA CD104-100MC (10µH)
**AVX TPSD226M025R0200
†
MAX I
OUT
L1
I
OUT
4.7µH 0.7A
10µH 0.8A
U
U
U
12V Output Efficiency
100
V
IN
= 5V
90
80
70
60
50
0.01
0.1
OUTPUT CURRENT (A)
1
LT1371 • TA02
1
LINER [ LINEAR TECHNOLOGY ]
