LT1371 Datasheet, PDF (1/16 Pages) Linear Technology – 500kHz High Efficiency 3A Switching Regulator

LT1371
500kHz High Efficiency
3A Switching Regulator
FEATURES
s _{Faster Switching with Increased Efficiency}
s _{Uses Small Inductors: 4.7µH}
s _{All Surface Mount Components}
s _{Low Minimum Supply Voltage: 2.7V}
s _{Quiescent Current: 4mA Typ}
s _{Current Limited Power Switch: 3A}
s _{Regulates Positive or Negative Outputs}
s _{Shutdown Supply Current: 12µA Typ}
s _{Easy External Synchronization}
U
APPLICATIONS
s _{Boost Regulators}
s _{Laptop Computer Supplies}
s _{Multiple Output Flyback Supplies}
s _{Inverting Supplies}
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.
TYPICAL APPLICATION
5V to 12V Boost Converter
ON
OFF
+ C1**
22µF
25V
5V _L1*
4.7µH
V_IN
S/S
V_SW
LT1371
FB
GND
V_C
C2
0.047µF
R3
2k
D1
MBRS330T3
R1
53.6k
1%
V_OUT†
12V
+
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 IOUT}
L1 I_OUT
4.7µH 0.7A
10µH 0.8A
12V Output Efficiency
100
V_IN = 5V
90
80
70
60
50
0.01
0.1
1
OUTPUT CURRENT (A)
LT1371 • TA02
1