LT1374 Datasheet, PDF (1/32 Pages) Linear Technology – 4.5A, 500kHz Step-Down Switching Regulator

FEATURES
s _{Constant 500kHz Switching Frequency}
s _{High Power 16-Pin TSSOP Package Available}
s _{Uses All Surface Mount Components}
s _{Inductor Size Reduced to 1.8µH}
s _{Saturating Switch Design: 0.07Ω}
s _{Effective Supply Current: 2.5mA}
s _{Shutdown Current: 20µA}
s _{Cycle-by-Cycle Current Limiting}
s _{Easily Synchronizable}
U
APPLICATIO S
s _{Portable Computers}
s _{Battery-Powered Systems}
s _{Battery Chargers}
s _{Distributed Power}
LT1374
4.5A, 500kHz Step-Down
Switching Regulator
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.
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
1374fb
1