3

LT1185

1185ff

The

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Load Regulation (Note 7)

0.05

0.3

%

Line Regulation (Note 7)

0.002

0.01

%/V

Minimum Input Voltage

4.0

V

4.3

V

Internal Current Limit (See Graph for

1.5V

3.3

3.6

4.2

A

Guaranteed Curve) (Note 12)

●

3.1

4.4

A

●

2.0

3.0

4.2

A

●

1.0

1.7

2.6

A

●

0.2

0.4

1.0

A

External Current Limit

5k

●

15k

A•

Ω

Programming Constant

(Note 11)

External Current Limit Error

1A

A

●

A

Quiescent Supply Current

●

2.5

3.5

mA

4V

Supply Current Change with Load

●

25

40

mA/A

●

10

25

mA/A

REF Pin Shutoff Current

●

0.4

2

7

µA

Thermal Regulation (See Applications

0.005

0.014

%/W

Information)

Reference Voltage Temperature Coefficient

(Note 8)

0.003

0.01

%/

°C

Thermal Resistance Junction to Case

TO-3 Control Area

1

°C/W

Power Transistor

3

°C/W

TO-220 Control Area

1

°C/W

Power Transistor

3

°C/W

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: Reference voltage is guaranteed both at nominal conditions (no

load, 25

°C) and at worst-case conditions of load, line, power and

temperature. An intermediate value can be calculated by adding the effects

of these variables in the actual application. See the Applications

Information section of this data sheet.

Note 3: Dropout voltage is tested by reducing input voltage until the

output drops 1% below its nominal value. Tests are done at 0.5A and 3A.

The power transistor looks basically like a pure resistance in this range so

that minimum differential at any intermediate current can be calculated by

0.5A, see graph.

Note 4: “Minimum input voltage” is limited by base emitter voltage drive

of the power transistor section, not saturation as measured in Note 3. For

output voltages below 4V, “minimum input voltage” specification may limit

dropout voltage before transistor saturation limitation.

Note 5: Supply current is measured on the ground pin, and does not

Note 6: The 25W power level is guaranteed for an input-output voltage of

8.3V to 17V. At lower voltages the 3A limit applies, and at higher voltages

the internal power limiting may restrict regulator power below 25W. See

graphs.

Note 7: Line and load regulation are measured on a pulse basis with a

pulse width of

≈2ms, to minimize heating. DC regulation will be affected

by thermal regulation and temperature coefficient of the reference. See

Applications Information section for details.

Note 8: Guaranteed by design and correlation to other tests, but not

tested.

the LT1185M. Power transistor area and control circuit area have different

the LT1185C and LT1185I and 150

°C for the LT1185M. Power area limits

are 150

°C for LT1185C and LT1185I and 175°C for LT1185M.

Note 11: Current limit is programmed with a resistor from REF pin to GND

other current limit tests.

ELECTRICAL CHARACTERISTICS