National Semiconductor LM1084 Technical data

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LM1084
5A Low Dropout Positive Regulators

LM1084 5A Low Dropout Positive Regulators

June 2005

General Description

The LM1084 is a series of low dropout voltage positive
regulators with a maximum dropout of 1.5V at 5A of load
current. It has the same pin-out as National Semiconductor’s
industry standard LM317.

The LM1084 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 intergrate the adjust resistors.

The LM1084 circuit includes a zener trimmed bandgap ref­erence, current limiting and thermal shutdown.

The LM1084 series is available in TO-220 and TO-263 pack­ages. Refer to the LM1085 for the 3A version, and the
LM1086 for the 1.5A version.

Connection Diagrams

TO-220

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Top View

TO-263

Features

n Available in 3.3V, 5.0V, 12V and Adjustable Versions
n Current Limiting and Thermal Protection
n Output Current 5A
n Industrial Temperature Range −40˚C to 125˚C
n Line Regulation 0.015% (typical)
n Load Regulation 0.1% (typical)

Applications

n Post Regulator for Switching DC/DC Conveter
n High Efficiency Linear Regulators
n Battery Charger

Application Circuit

1.2V to 15V Adjustable Regulator

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Top View

Basic Functional Diagram, Adjustable Version

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© 2005 National Semiconductor Corporation DS100946 www.national.com

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Ordering Information

LM1084

3-lead TO-263 −40˚C to +125˚C LM1084IS-ADJ Rails

3-lead TO-220 −40˚C to + 125˚C LM1084IT-ADJ Rails

Package Temperature Range Part Number Transport Media NSC Drawing

LM1084ISX-ADJ Tape and Reel

LM1084IS-12 Rails

LM1084ISX-12 Tape and Reel

LM1084IS-3.3 Rails

LM1084ISX-3.3 Tape and Reel

LM1084IS-5.0 Rails

LM1084ISX-5.0 Tape and Reel

LM1084IT-12 Rails

LM1084IT-3.3 Rails

LM1084IT-5.0 Rails

Simplified Schematic

TS3B

T03B

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LM1084

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 (TJ)(Note 3) 150˚C

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

LM1084-ADJ 29V

Operating Ratings (Note 1)

LM1084-12 18V

LM1084-3.3 27V

LM1084-5.0 25V

Power Dissipation (Note 2) Internally Limited

Junction Temperature Range (T

Control Section −40˚C to 125˚C

Output Section −40˚C to 150˚C

) (Note 3)

J

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

Reference Voltage LM1084-ADJ

= 10mA, VIN−V

I

OUT

10mA ≤I

OUT

≤ I

FULL LOAD

=3V

OUT

,1.5V ≤ (VIN−V

(Note 7)

V

OUT

Output Voltage
(Note 7)

LM1084-3.3

= 0mA, VIN=8V

I

OUT

0 ≤ I

OUT≤IFULL LOAD

, 4.8V≤ VIN≤15V

LM1084-5.0

= 0mA, VIN=8V

I

OUT

0 ≤ I

OUT

≤ I

FULL LOAD

, 6.5V ≤ VIN≤ 20V

LM1084-12

= 0mA, VIN= 15V

I

OUT

∆V

OUT

Line Regulation
(Note 8)

OUT

≤ I

FULL LOAD

0 ≤ I

LM1084-ADJ

=10mA, 1.5V≤ (VIN-V

I

OUT

, 13.5V ≤ VIN≤ 25V

OUT

LM1084-3.3

= 0mA, 4.8V ≤ VIN≤ 15V

I

OUT

LM1084-5.0
I

= 0mA, 6.5V ≤ VIN≤ 20V

OUT

LM1084-12

=0mA, 13.5V ≤ VIN≤ 25V

I

OUT

∆V

OUT

Load Regulation
(Note 8)

LM1084-ADJ
(V

IN-VOUT

) = 3V, 10mA ≤ I

OUT

LM1084-3.3

= 5V, 0 ≤ I

V

IN

OUT

≤ I

FULL LOAD

LM1084-5.0

= 8V, 0 ≤ I

V

IN

OUT

≤ I

FULL LOAD

LM1084-12

Dropout Voltage
(Note 9)

= 15V, 0 ≤ I

V

IN

LM1084-ADJ, 3.3, 5, 12

, ∆V

∆V

REF

OUT

OUT

= 1%, I

≤ I

FULL LOAD

=5A 1.3 1.5 V

OUT

) ≤ 15V

≤ I

FULL LOAD

OUT

) ≤ 25V

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

(Note 6)

1.262

1.270

3.330

3.365

5.050

5.100

12.120

12.240

0.2

0.2

6

6

10

10

25

25

0.3

0.4

15

20

20

35

36

72

Units

V
V

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 junc-

LM1084

tion temperature range for operation.

Symbol Parameter Conditions

I

LIMIT

Current Limit LM1084-ADJ

V

IN−VOUT

V

IN−VOUT

=5V
= 25V

LM1084-3.3
VIN=8V 5.5 8.0 A

LM1084-5.0

= 10V 5.5 8.0 A

V

IN

LM1084-12
VIN= 17V 5.5 8.0 A

Minimum Load
Current (Note 10)

LM1084-ADJ
V

IN−VOUT

= 25V 5 10.0 mA

Quiescent Current LM1084-3.3

VIN= 18V 5.0 10.0 mA

LM1084-5.0

≤ 20V 5.0 10.0 mA

V

IN

LM1084-12

≤ 25V 5.0 10.0 mA

V

IN

Thermal Regulation T

Ripple Rejection f

= 25˚C, 30ms Pulse 0.003 0.015 %/W

A

= 120Hz, = C

RIPPLE

=5A

I

OUT

LM1084-3.3, V

LM1084-5.0, V

LM1084-12 V

ADJ

= 6.3V 60 72 dB

IN

=8V 60 68 dB

IN

= 15V 54 60 dB

IN

= 25µF Tantalum,

OUT

, = 25µF, (VIN−VO)=3V

Adjust Pin Current LM1084 55 120 µA

Adjust Pin Current
Change

10mA ≤ I

1.5V ≤ V

≤ I

OUT

IN−VOUT

FULL LOAD

≤ 25V

,

Temperature
Stability

Long Term Stability T

RMS Output Noise
(% of V

OUT

)

Thermal Resistance
Junction-to-Case

=125˚C, 1000Hrs 0.3 1.0 %

A

10Hz ≤ f≤ 10kHz 0.003 %

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

Min

(Note 6)

5.5

0.3

60 75 dBLM1084-ADJ, C

Typ

(Note 5)

(Note 6)

8.0

0.6

0.2 5 µA

0.5 %

0.65/2.7

0.65/2.7

Max

Units

A
A

˚C/W
˚C/W

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

is P

=(T

D

J(max)–TA

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

FULLLOAD

dissipation for the LM1084 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
dissipation 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.

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

is defined in the current limit curves. The I

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

J(max)

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

FULLLOAD