
1
LT1374
1374fd
4.5A, 500kHz Step-Down
Switching Regulator
■ Constant 500kHz Switching Frequency
■ High Power 16-Pin TSSOP Package Available
■
Uses All Surface Mount Components
■ Inductor Size Reduced to 1.8
H
■ Saturating Switch Design: 0.07
■
Effective Supply Current: 2.5mA
■ Shutdown Current: 20A
■ Cycle-by-Cycle Current Limiting
■
Easily Synchronizable
The LT
1374 is a 500kHz monolithic buck mode switching
regulator. A 4.5A switch is included on the die along with
all the necessary oscillator, control and logic circuitry. High
switching frequency allows a considerable reduction in the
size of external components. The topology is current mode
for fast transient response and good loop stability. Both
fixed output voltage and adjustable parts are available.
A special high speed bipolar process and new design tech-
niques achieve high efficiency at high switching frequency.
Efficiency is maintained over a wide output current range
by using the output to bias the circuitry and by utilizing a
supply boost capacitor to saturate the power switch.
The LT1374 is available in standard 7-pin DD, TO-220, fused
lead SO-8 and 16-pin exposed pad TSSOP packages. Full
cycle-by-cycle short-circuit protection and thermal shut-
down are provided. Standard surface mount external parts
may be used, including the inductor and capacitors. There
is the optional function of shutdown or synchronization. A
shutdown signal reduces supply current to 20A. Synchro-
nization allows an external logic level signal to increase the
internal oscillator from 580kHz to 1MHz.
, LTC and LT are registered trademarks of Linear Technology Corporation.
5V Buck Converter
LOAD CURRENT (A)
0
EFFICIENCY
(%)
100
95
90
85
80
75
70
2.0
2.5
3.0
3.5
1374 TA02
0.5
1.0
1.5
4.0
VOUT = 5V
VIN = 10V
L = 10H
Efficiency vs Load Current
BOOST
LT1374-5
VIN
SHDN
OUTPUT**
5V, 4.25A
* RIPPLE CURRENT RATING ≥ IOUT/2
** INCREASE L1 TO 10H FOR LOAD CURRENTS ABOVE 3.5A AND TO 20H ABOVE 4A
SEE APPLICATIONS INFORMATION
INPUT
6V TO 25V
1374 TA01
C2
0.27F
CC
1.5nF
D1
MBRS330T3
C1
100F, 10V
SOLID
TANTALUM
C3*
10F TO
50F
DEFAULT
= ON
D2
CMDSH3 OR FMMD914
L1**
5H
VSW
SENSE
BIAS
GND
VC
+
■ Portable Computers
■
Battery-Powered Systems
■ Battery Chargers
■ Distributed Power
FEATURES
DESCRIPTIO
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APPLICATIO S
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TYPICAL APPLICATIO
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Protected by U.S. Patents, Including 6111439, 5668493, 5656965