LT3431 查看數據表（PDF） - Linear Technology

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LT3431

High Voltage, 3A, 500kHz Step-Down Switching Regulator

Linear Technology 

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

VIN

12V

(TRANSIENTS

TO 60V)

2.2µF†

100V

CERAMIC

6

BOOST

3, 4

2, 5

VIN

SW

LT3431

15

SHDN

10

BIAS

14

SYNC

GND

1, 8, 9, 16

12

FB

VC

11

220pF

1.5k

0.22µF

10µH**

30BQ060

15.4k

4.99k

VOUT

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

VIN = 12V

L = 15µH

90

80

VOUT = 5V

VOUT = 3.3V

70

60

50

0

0.5 1.0 1.5 2.0 2.5

LOAD CURRENT (A)

3431 TA02

sn3431 3431fs

1

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