LT3645

1

3645f

LOAD CURRENT (mA)

0

100

50

60

70

80

90

200

300

3645 TA01b

400

500

TYPICAL APPLICATION

FEATURES

DESCRIPTION

36V 500mA Step-Down

Regulator and 200mA LDO

buck regulator and a 200mA low dropout linear regula-

tor (LDO). The wide input voltage range of 3.6V to 36V

makes the LT3645 suitable for regulating power from a

wide variety of sources, including 24V industrial supplies

and automotive batteries. Its high operating frequency

allows the use of tiny, low cost inductors and capacitors,

resulting in a very small solution.

Cycle-by-cycle current limit and frequency foldback pro-

vide protection against shorted outputs. Soft-start and

frequency foldback eliminate input current surge during

start-up.

down to 1.2V. It supplies 200mA of output current with a

typical dropout voltage of 310mV.

Other features of the LT3645 include a <2μA shutdown,

short circuit protection, soft-start and thermal shutdown.

The LT3645 is available in the thermally enhanced 16-lead

(3mm × 3mm) QFN package, or a 12-lead MSE package.

3.3V/5V Step-Down Converter

APPLICATIONS

L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners.

Operation from 3.6V to 36V

Overvoltage Lockout Protects Circuit Through

55V Transients on Input

1.2V to 16V Input; 0.8V to 8V Output

QFN and 12-Lead MSE Packages

Buck Regulator Efficiency

1μF

3645 TA01a

PGOOD

6.2V TO 36V

GND

SW

DA

FB

FB2

EN2

EN/UVLO

NPG

OUT2

10μF

5V

300mA

3.3V

200mA

15μH

52.3k

31.6k

10k

10k

BOOST

LT3645

2.2μF

0.1μF

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