LT1374_15 Datasheet, PDF (1/32 Pages) Linear Technology – 4.5A, 500kHz Step-Down Switching Regulator

LT1374
4.5A, 500kHz Step-Down
Switching Regulator
FEATURES
■ _{Constant 500kHz Switching Frequency}
■ _{High Power 16-Pin TSSOP Package Available}
■ _{Uses All Surface Mount Components}
■ _{Inductor Size Reduced to 1.8µH}
■ _{Saturating Switch Design: 0.07Ω}
■ _{Effective Supply Current: 2.5mA}
■ _{Shutdown Current: 20µA}
■ _{Cycle-by-Cycle Current Limiting}
■ _{Easily Synchronizable}
U
APPLICATIO S
■ _{Portable Computers}
■ _{Battery-Powered Systems}
■ _{Battery Chargers}
■ _{Distributed Power}
DESCRIPTIO
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 20µA. 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.
Protected by U.S. Patents, Including 6111439, 5668493, 5656965
TYPICAL APPLICATIO
5V Buck Converter
D2
CMDSH3 OR FMMD914
INPUT
6V TO 25V _{C3* +}
10µF TO
50µF
DEFAULT
= ON
C2
0.27µF
BOOST
V_IN
V_SW
LT1374-5 BIAS
SHDN
GND
SENSE
V_C
C_C
1.5nF
L1**
5µH
D1
+
MBRS330T3
* RIPPLE CURRENT RATING ≥ I_OUT/2
** INCREASE L1 TO 10µH FOR LOAD CURRENTS ABOVE 3.5A AND TO 20µH ABOVE 4A
SEE APPLICATIONS INFORMATION
OUTPUT**
5V, 4.25A
C1
100µF, 10V
SOLID
TANTALUM
1374 TA01
Efficiency vs Load Current
100
V_OUT = 5V
V_IN = 10V
95 _{L = 10µH}
90
85
80
75
70
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
LOAD CURRENT (A)
1374 TA02
1374fd
1