1

LT1185

1185ff

Low Dropout Regulator

Ω

■

Dropout Voltage: 0.75V at 3A

■

■

Shutdown Capability

■

Low Quiescent Current: 2.5mA

The LT1185 uses a saturation-limited NPN transistor as

the pass element. This device gives the linear dropout

characteristics of a FET pass element with significantly

less die area. High efficiency is maintained by using special

anti-saturation circuitry that adjusts base drive to track

load current. The “on resistance” is typically 0.25

Ω.

Accurate current limit is programmed with a single 1/8W

external resistor, with a range of zero to three amperes. A

second, fixed internal limit circuit prevents destructive

currents if the programming current is accidentally over-

ranged. Shutdown of the regulator output is guaranteed

when the program current is less than 1

µA, allowing

external logic control of output voltage.

The LT1185 has all the protection features of previous

LTC regulators, including power limiting and thermal

shutdown.

5V, 3A Regulator with 3.5A Current Limit

Dropout Voltage

+

–

2.37k

2.67k

2

µF

TANT

REF

GND

FB

LT1185

2

µF

TANT

4.3k

+

–

6V TO 16V

5V AT 3A

LT1185 • TA01

+

+

LOAD CURRENT (A)

0

0.8

1.0

1.2

4

LT1185 • TA02

0.6

0.4

0

1

2

3

0.2

1.6

1.4

The LT

current limit and remote sense capability. It can be used as

a positive output regulator with floating input or as a

standard negative regulator with grounded input. The

output voltage range is 2.5V to 25V, with

±1%accuracyon

the internal reference voltage.

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.