1

LT1185

S

FEATURE

Low Dropout Regulator

s

Low Resistance Pass Transistor: 0.25

Ω

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Dropout Voltage: 0.75V at 3A

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±1% Reference Voltage

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Accurate Programmable Current Limit

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Shutdown Capability

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Internal Reference Available

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Standard 5-Lead Packages

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Full Remote Sense

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Low Quiescent Current:

≈2.5mA

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Good High Frequency Ripple Rejection

The LT1185 uses a saturation-limited NPN transistor as

the pass element. This device gives the linear dropout

characteristics of an 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 shut-

down. The 4-lead TO-3 package is specified for –55

°C to

150

°C operation and the 5-lead TO-220 is specified over

0

°C to 125°C.

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

APPLICATI

TYPICAL

5V, 3A Regulator with 3.5A Current Limit

Dropout Voltage

+

–

R1

2.37k

R2

2.67k

C1

2

µF

TANT

REF

GND

FB

LT1185

C2

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

DESCRIPTIO

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.