NSC LM1085IS-5.0, LM1085IS-3.3, LM1085IT-ADJ, LM1085IT-3.3, LM1085IT-12 Datasheet

LM1085
3A Low Dropout Positive Regulators

LM1085 3A Low Dropout Positive Regulators

July 1999

General Description

The LM1085 is a series of low dropout positive voltage regu­lators with a maximum dropout of 1.5V at 3A of load current.
It has thesamepin-out as National Semiconductor’s industry
standard LM317.

The LM1085 is available in an adjustable version, which can
set the output voltage with only two external resistors. It is
also available in three fixed voltages: 3.3V, 5.0V and 12.0V.
The fixed versions integrate the adjust resistors.

The LM1085 circuit includes a zener trimmed bandgap refer­ence, current limiting and thermal shutdown.

The LM1085 series is available in TO-220 and TO-263 pack­ages.

Connection Diagrams

TO-220

DS100947-2

Top View

Features

n Available in 3.3V, 5.0V, 12V and Adjustable Versions
n Current Limiting and Thermal Protection
n Output Current 3A
n Line Regulation 0.015%(typical)
n Load Regulation 0.1%(typical)

Applications

n High Efficiency Linear Regulators
n Battery Charger
n Post Regulation for Switching Supplies
n Constant Current Regulator
n Microprocessor Supply

TO-263

DS100947-4

Top View

Basic Functional Diagram, Adjustable Version

DS100947-65

© 1999 National Semiconductor Corporation DS100947 www.national.com

Ordering Information

Package Temperature Range Part Number Transport Media NSC Drawing

3-lead TO-263 −40˚C to +125˚C LM1085IS-ADJ Rails

LM1085ISX-ADJ Tape and Reel

LM1085IS-12 Rails

LM1085ISX-12 Tape and Reel

LM1085IS-3.3 Rails

LM1085ISX-3.3 Tape and Reel

LM1085IS-5.0 Rails

LM1085ISX-5.0 Tape and Reel

3-lead TO-220 −40˚C to + 125˚C LM1085IT-ADJ Rails

LM1085IT-12 Rails
LM1085IT-3.3 Rails
LM1085IT-5.0 Rails

Simplified Schematic

TS3B

T03B

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DS100947-34

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Junction Temperature (T

)(Note 3) 150˚C

J

Storage Temperature Range -65˚C to 150˚C
Lead Temperature 260˚C, to 10 sec
ESD Tolerance (Note 4) 2000V

Maximum Input to Output Voltage Differential

LM1085-ADJ 29V
LM1085-12 18V
LM1085-3.3 27V
LM1085-5.0 25V

Operating Ratings (Note 1)

Junction Temperature Range (T

Control Section −40˚C to 125˚C
Output Section −40˚C to 150˚C

) (Note 3)

J

Power Dissipation (Note 2) Internally Limited

Electrical Characteristics

Typicals and limits appearing in normal type apply for TJ= 25˚C. Limits appearing in Boldface type apply over the entire junc­tion temperature range for operation.

Symbol Parameter Conditions

V

REF

V

OUT

Reference
Voltage

Output Voltage
(Note 7)

LM1085-ADJ

=

10mA, V

I

OUT

10mA ≤I

OUT

(Note 7)
LM1085-3.3

=

0mA, V

I

OUT

0 ≤ I

OUT≤IFULL LOAD

IN−VOUT

≤ I

FULL LOAD

IN

=

5V

=
,1.5V ≤ (VIN−V

, 4.8V≤ VIN≤15V

LM1085-5.0
I

OUT

0 ≤ I

=

OUT

0mA, V

≤ I

FULL LOAD

=

8V

IN

, 6.5V ≤ VIN≤ 20V

LM1085-12

∆V

OUT

Line Regulation
(Note 8)

=

0mA, V

I

OUT

0 ≤ I

OUT

LM1085-ADJ

=

10mA, 1.5V≤ (V

I

OUT

≤ I

FULL LOAD

=

15V

IN

, 13.5V ≤ VIN≤ 25V

IN-VOUT

LM1085-3.3
I

OUT

=

0mA, 4.8V ≤ V

IN

≤ 15V

LM1085-5.0

=

I

OUT

0mA, 6.5V ≤ V

IN

≤ 20V

LM1085-12

∆V

OUT

Load Regulation
(Note 8)

=

0mA, 13.5V ≤ V

I

OUT

LM1085-ADJ
(V

IN-VOUT

)=3V, 10mA ≤ I

IN

≤ 25V

LM1085-3.3

=

5V, 0 ≤ I

V

IN

OUT

≤ I

FULL LOAD

LM1085-5.0

=

8V, 0 ≤ I

V

IN

OUT

≤ I

FULL LOAD

LM1085-12

Dropout Voltage
(Note 9)

=

15V, 0 ≤ I

V

IN

LM1085-3.3/5/12/ADJ

=

1%,I

∆V

REF

≤ I

OUT

FULL LOAD

=

3A 1.3 1.5 V

OUT

3V

OUT

) ≤ 15V

≤ I

FULL LOAD

OUT

) ≤ 15V

Min

(Note

6)

1.238

1.225

3.270

3.235

4.950

4.900

11.880

11.760

Typ

(Note

5)

1.250

1.250

3.300

3.300

5.000

5.000

12.000

12.000

0.015

0.035

0.5

1.0

0.5

1.0

1.0

2.0

0.1

0.2

3

7

5

10

12

24

Max

(Note6)Units

1.262

1.270

3.330

3.365

5.050

5.100

12.120

12.240VV

0.2

0.2

6

6

10

10

25

25

0.3

0.4

15

20

20

35

36

72

V
V

V
V

V
V

%
%

mV
mV

mV
mV

mV
mV

%
%

mV
mV

mV
mV

mV
mV

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Electrical Characteristics (Continued)

Typicals and limits appearing in normal type apply for TJ= 25˚C. Limits appearing in Boldface type apply over the entire junc­tion temperature range for operation.

Symbol Parameter Conditions

I

LIMIT

Current Limit LM1085-ADJ

V

IN−VOUT

V

IN−VOUT

=

5V

=

25V

Min

(Note

6)

3.2

0.2

LM1085-3.3

=

8V 3.2 5.5 A

V

IN

LM1085-5.0

=

V

10V 3.2 5.5 A

IN

LM1085-12

=

17V 3.2 5.5 A

V

Minimum Load
Current (Note 10)

Quiescent
Current

IN

LM1085-ADJ

=

V

IN−VOUT

25V 5.0 10.0 mA

LM1085-3.3

≤ 18V 5.0 10.0 mA

V

IN

LM1085-5.0

≤ 20V 5.0 10.0 mA

V

IN

LM1085-12

≤ 25V 5.0 10.0 mA

V

IN

Thermal
Regulation

Ripple Rejection f

Adjust Pin

=

T

25˚C, 30ms Pulse .004 0.02

A

=

120Hz, C

RIPPLE

3A

LM1085-3.3, V
LM1085-5.0, V
LM1085-12 V

IN

=

25µF Tantalum, I

OUT

=

25µF, (V

ADJ

=

6.3V 60 72 dB

IN

=

8V 60 68 dB

IN

=

15V 54 60 dB

IN−VO

)=3V

OUT

=

60 75 dBLM1085-ADJ, C

LM1085 55 120 µA

Current
Adjust Pin

Current Change

10mA ≤ I

OUT

≤ I

FULL LOAD

, 1.5V ≤ VIN−V

OUT

≤ 25V

Temperature
Stability

Long Term
Stability

RMS Output

=

T

125˚C, 1000Hrs

A

10Hz ≤ f≤ 10kHz 0.003

Noise

OUT

)

3-Lead TO-263: Control Section/Output Section
3-Lead TO-220: Control Section/Output Section

(%of V
Thermal

Resistance
Junction-to-Case

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in­tended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.

Note 2: Power dissipation is kept in a safe range by current limiting circuitry. Refer to Overload Recovery in Application Notes.
Note 3: The maximum power dissipation is a function of T

=(T

P

D

Note 4: For testing purposes, ESD was applied using human body model, 1.5kΩ in series with 100pF.
Note 5: Typical Values represent the most likely parametric norm.
Note 6: All limits are guaranteed by testing or statistical analysis.
Note 7: I

dissipation for the LM1085 is only achievable over a limited range of input-to-output voltage.
Note 8: Load and line regulation are measured at constant junction temperature, and are guaranteed up to the maximum power dissipation of 30W. Power dissipa-

tion is determined by the input/output differential and the output current. Guaranteed maximum power dissipation will not be available over the full input/output range.

Note 9: Dropout voltage is specified over the full output current range of the device.
Note 10: The minimum output current required to maintain regulation.

)/θJA. All numbers apply for packages soldered directly into a PC board. Refer to Thermal Considerations in the Application Notes.

J(max)–TA

is defined in the current limit curves. The I

FULL LOAD

, θJA, and TA. The maximum allowable power dissipation at any ambient temperature is

J(max)

Curve defines the current limit as a function of input-to-output voltage. Note that 30W power

FULL LOAD

Typ

(Note

5)

Max

(Note6)Units

5.5

0.5

0.2 5 µA

0.5

0.3 1.0

0.7/3.0

0.7/3.0

A
A

%

/W

%

%
%

˚C/W
˚C/W

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