LTC3255

1

3255f

The LTC®3255 is a switched-capacitor step-down DC/DC

converter that produces a regulated output (2.4V to 12.5V

adjustable) from a 4V to 48V input. In applications where

the input voltage exceeds twice the output voltage, 2:1

capacitivechargepumpingextendsoutputcurrentcapabil-

ity beyond input supply current limits. At no load, Burst

excels in 4mA to 20mA current loop applications. The

device enables current multiplication; a 4mA input current

can power a 7.4mA load continuously. Alternatively, the

LTC3255 serves as a higher efficiency replacement for

linear regulators and provides a space-saving inductor-

free alternative to buck DC/DC converters.

The LTC3255 withstands reverse-polarity input supplies

and output short-circuits without damage. Safety features

including current limit and overtemperature protection

further enhance robustness. The LTC3255 is available in

thermally enhanced 10-lead MSOP and low profile 3mm

× 3mm 10-lead DFN packages.

TYPICAL APPLICATION

FEATURES

DESCRIPTION

Fault Protected 50mA

Step-Down Charge Pump

7.4mA DC Supply from 4mA to 20mA Current Loop

APPLICATIONS

n

Input Voltage Range: 4V to 48V

n

Adjustable Regulated Output: 2.4V to 12.5V

n

Output Current: 50mA Maximum

n

16μA Quiescent Current in Regulation at No Load

n

Input Fault Protection from –52V to 60V

n

Multimode Charge Pump (2:1, 1:1) with Automatic

Mode Switching Maintains Regulation Over Wide

n

Input Voltage Shunt Mode for Current-Fed Applications

n

Power Good Output

n

Overtemperature and Short-Circuit Protection

n

Operating Junction Temperature: 150°C Maximum

n

Thermally Enhanced 10-Lead MSOP and 10-Lead

(3mm

× 3mm) DFN packages

n

Industrial Control, Factory Automation, Sensors, and

SCADA Systems

n

Housekeeping Power Supplies

n

Current-Boosting Voltage Regulators for 4mA to

20mA Current Loops

L

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

and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners.

EN

220k

10µF

3255 TA01a

0.1µF

4mA TO 20mA INPUT

>10V COMPLIANCE

1µF

1µF

OUTPUT

3.3V

7.4mA

LTC3255

GND

SHUNT

BIAS

PGOOD

+

–

PGOOD

FB

2.15M

1.21M

Available Output Current

vs Input Current

4

8

12

14

20

6

10

16

18

INPUT CURRENT (mA)

16

31

34

37

40

10

25

13

28

7

4

22

19

3255 TA01b

INCREASED

AVAILABLE

INPUT

CURRENT