LT3431_15 Datasheet, PDF (1/28 Pages) Linear Technology – High Voltage, 3A, 500kHz Step-Down Switching Regulator

LT3431
High Voltage, 3A,
500kHz Step-Down
Switching Regulator
FEATURES
s _{Wide Input Range: 5.5V to 60V}
s _{3A Peak Switch Current}
s _{Small Thermally Enhanced 16-Pin TSSOP Package}
s _{Constant 500kHz Switching Frequency}
s _{Saturating Switch Design: 0.1Ω}
s _{Peak Switch Current Maintained Over}
Full Duty Cycle Range
s _{Effective Supply Current: 2.5mA}
s _{Shutdown Current: 30µA}
s _{1.2V Feedback Reference Voltage}
s _{Easily Synchronizable}
s _{Cycle-by-Cycle Current Limiting}
U
APPLICATIO S
s _{Industrial and Automotive Power Supplies}
s _{Portable Computers}
s _{Battery Chargers}
s _{Distributed Power Systems}
DESCRIPTIO
The LT^®3431 is a 500kHz monolithic buck switching regu-
lator that accepts input voltages up to 60V. A high efficiency
3A, 0.1Ω switch is included on the die along with all the nec-
essary oscillator, control and logic circuitry. A current mode
architecture provides fast transient response and good loop
stability.
Special design techniques and a new high voltage process
achieve high efficiency over a wide input range. 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. Patented circuitry
maintains peak switch current over the full duty cycle range.
A shutdown pin reduces supply current to 30µA and the de-
vice can be externally synchronized from 580kHz to 700kHz
with logic level inputs.
The LT3431 is available in a thermally enhanced 16-pin
TSSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
5V, 2A Buck Converter
MMSD914TI
V_IN
12V
(TRANSIENTS
TO 60V)
2.2µF^†
100V
CERAMIC
6
BOOST
3, 4
2, 5
V_IN
SW
LT3431
15
SHDN
10
BIAS
14
SYNC
GND
1, 8, 9, 16
12
FB
V_C
11
220pF
1.5k
0.22µF
10µH**
30BQ060
15.4k
4.99k
V_OUT
5V
2A
47µF
CERAMIC
15nF
** INCREASE INDUCTOR VALUE FOR LOAD CURRENTS ABOVE 2A
(SEE APPLICATIONS INFORMATION—MAXIMUM OUTPUT LOAD CURRENT)
† _{UNITED CHEMI-CON THCS50EZA225ZT}
3431 TA01
Efficiency vs Load Current
100
V_IN = 12V
L = 15µH
90
80
V_OUT = 5V
V_OUT = 3.3V
70
60
50
0
0.5 1.0 1.5 2.0 2.5
LOAD CURRENT (A)
3431 TA02
sn3431 3431fs
1