LM1086
1.5A Low Dropout Positive Regulators
General Description
The LM1086 is a series of low dropout positive voltage
regulators with a maximum dropout of 1.5V at 1.5A of load
current. It has the same pin-out as National Semiconductor's
industry standard LM317.
The LM1086 is available in an adjustable version, which can
set the output voltage with only two external resistors. It is
also available in six fixed voltages: 1.8V, 2.5V, 2.85V, 3.3V,
3.45V and 5.0V. The fixed versions integrate the adjust
resistors.
The LM1086 circuit includes a zener trimmed bandgap ref-
erence, current limiting and thermal shutdown.
The LM1086 series is available in TO-220, TO-263, and LLP
packages. Refer to the LM1084 for the 5A version, and the
LM1085 for the 3A version.
Features
n
Available in 1.8V, 2.5V, 2.85V, 3.3V, 3.45V, 5V and
Adjustable Versions
n
Current Limiting and Thermal Protection
n
Output Current
1.5A
n
Line Regulation
0.015% (typical)
n
Load Regulation
0.1% (typical)
Applications
n
SCSI-2 Active Terminator
n
High Efficiency Linear Regulators
n
Battery Charger
n
Post Regulation for Switching Supplies
n
Constant Current Regulator
n
Microprocessor Supply
Connection Diagrams
TO-220
TO-263
LLP
10094802
Top View
10094804
Top View
10094866
Pins 6, 7, and 8 must be tied together.
Top View
Basic Functional Diagram, Adjustable Version
10094865
Application Circuit
10094852
1.2V to 15V Adjustable Regulator
June 2005
LM1086
1.5A
Low
Dropout
Positive
Regulators
© 2005 National Semiconductor Corporation
DS100948
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Maximum Input-to-Output Voltage Differential
LM1086-ADJ
29V
LM1086-1.8
27V
LM1086-2.5
27V
LM1086-2.85
27V
LM1086-3.3
27V
LM1086-3.45
27V
LM1086-5.0
25V
Power Dissipation (Note 2)
Internally Limited
Junction Temperature (T
J
)(Note 3)
150°C
Storage Temperature Range
-65°C to 150°C
Lead Temperature
260°C, to 10 sec
ESD Tolerance (Note 4)
2000V
Operating Ratings
(Note 1)
Junction Temperature Range (T
J
) (Note 3)
"C" Grade
Control Section
0°C to 125°C
Output Section
0°C to 150°C
"I" Grade
Control Section
-40°C to 125°C
Output Section
-40°C to 150°C
Electrical Characteristics
Typicals and limits appearing in normal type apply for T
J
= 25°C. Limits appearing in Boldface type apply over the entire junc-
tion temperature range for operation.
Symbol
Parameter
Conditions
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Units
V
REF
Reference Voltage
LM1086-ADJ
I
OUT
= 10mA, V
IN
-V
OUT
= 3V
10mA
I
OUT
I
FULL LOAD
,
1.5V
V
IN
-V
OUT
15V (Note 7)
1.238
1.225
1.250
1.250
1.262
1.270
V
V
V
OUT
Output Voltage
(Note 7)
LM1086-1.8
I
OUT
= 0mA, V
IN
= 5V
0
I
OUT
I
FULL LOAD
, 3.3V
V
IN
18V
1.782
1.764
1.8
1.8
1.818
1.836
V
LM1086-2.5
I
OUT
= 0mA, V
IN
= 5V
0
I
OUT
I
FULL LOAD
, 4.0V
V
IN
18V
2.475
2.450
2.50
2.50
2.525
2.55
V
LM1086-2.85
I
OUT
= 0mA, V
IN
= 5V
0
I
OUT
I
FULL LOAD
, 4.35V
V
IN
18V
2.82
2.79
2.85
2.85
2.88
2.91
V
V
LM1086-3.3
I
OUT
= 0mA, V
IN
= 5V
0
I
OUT
I
FULL LOAD
, 4.75V
V
IN
18V
3.267
3.235
3.300
3.300
3.333
3.365
V
V
LM1086-3.45
I
OUT
= 0mA, V
IN
= 5V
0
I
OUT
I
FULL LOAD
, 4.95V
V
IN
18V
3.415
3.381
3.45
3.45
3.484
3.519
V
V
LM1086-5.0
I
OUT
= 0mA, V
IN
= 8V
0
I
OUT
I
FULL LOAD
, 6.5V
V
IN
20V
4.950
4.900
5.000
5.000
5.050
5.100
V
V
V
OUT
Line Regulation
(Note 8)
LM1086-ADJ
I
OUT
=10mA, 1.5V
(V
IN
-V
OUT
)
15V
0.015
0.035
0.2
0.2
%
%
LM1086-1.8
I
OUT
= 0mA, 3.3V
V
IN
18V
0.3
0.6
6
6
mV
LM1086-2.5
I
OUT
= 0mA, 4.0V
V
IN
18V
0.3
0.6
6
6
mV
LM1086
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4
Electrical Characteristics
(Continued)
Typicals and limits appearing in normal type apply for T
J
= 25°C. Limits appearing in Boldface type apply over the entire junc-
tion temperature range for operation.
Symbol
Parameter
Conditions
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Units
LM1086-2.85
I
OUT
= 0mA, 4.35V
V
IN
18V
0.3
0.6
6
6
mV
mV
LM1086-3.3
I
OUT
= 0mA, 4.5V
V
IN
18V
0.5
1.0
10
10
mV
mV
LM1086-3.45
I
OUT
= 0mA, 4.95V
V
IN
18V
0.5
1.0
10
10
mV
mV
LM1086-5.0
I
OUT
= 0mA, 6.5V
V
IN
20V
0.5
1.0
10
10
mV
mV
V
OUT
Load Regulation
(Note 8)
LM1086-ADJ
(V
IN
-V
OUT
) = 3V, 10mA
I
OUT
I
FULL LOAD
0.1
0.2
0.3
0.4
%
%
LM1086-1.8 ,2.5, 2.85
V
IN
= 5V, 0
I
OUT
I
FULL LOAD
3
6
12
20
mV
mV
LM1086-3.3, 3.45
V
IN
= 5V, 0
I
OUT
I
FULL LOAD
3
7
15
25
mV
mV
LM1086-5.0
V
IN
= 8V, 0
I
OUT
I
FULL LOAD
5
10
20
35
mV
mV
Dropout Voltage
(Note 9)
LM1086-ADJ, 1.8, 2.5,2.85, 3.3, 3.45, 5
V
REF
,
V
OUT
= 1%, I
OUT
= 1.5A
1.3
1.5
V
I
LIMIT
Current Limit
LM1086-ADJ
V
IN
-V
OUT
= 5V
V
IN
-V
OUT
= 25V
1.50
0.05
2.7
0.15
A
A
LM1086-1.8,2.5, 2.85, 3.3, 3.45, V
IN
= 8V
1.5
2.7
A
LM1086-5.0, V
IN
= 10V
1.5
2.7
A
Minimum Load Current
(Note 10)
LM1086-ADJ
V
IN
-V
OUT
= 25V
5.0
10.0
mA
Quiescent Current
LM1086-1.8, 2.5, 2.85, V
IN
18V
5.0
10.0
mA
LM1086-3.3, V
IN
18V
5.0
10.0
mA
LM1086-3.45, V
IN
18V
5.0
10.0
mA
LM1086-5.0, V
IN
20V
5.0
10.0
mA
Thermal Regulation
T
A
= 25°C, 30ms Pulse
0.008
0.04
%/W
Ripple Rejection
f
RIPPLE
= 120Hz, C
OUT
= 25µF Tantalum,
I
OUT
= 1.5A
60
75
dB
LM1086-ADJ, C
ADJ
= 25µF, (V
IN
-V
O
) = 3V
LM1086-1.8, 2.5, 2.85, V
IN
= 6V
60
72
dB
LM1086-3.3, V
IN
= 6.3V
60
72
dB
LM1086-3.45, V
IN
= 6.3V
60
72
dB
LM1086-5.0 V
IN
= 8V
60
68
dB
Adjust Pin Current
LM1086
55
120
µA
Adjust Pin Current
Change
10mA
I
OUT
I
FULL LOAD
,
1.5V
(V
IN
-V
OUT
)
15V
0.2
5
µA
Temperature Stability
0.5
%
Long Term Stability
T
A
= 125°C, 1000Hrs
0.3
1.0
%
RMS Noise
(% of V
OUT
)
10Hz
f 10kHz
0.003
%
JC
Thermal Resistance
Junction-to-Case
3-Lead TO-263: Control Section/Output
Section
3-Lead TO-220: Control Section/Output
Section
1.5/4.0
1.5/4.0
°C/W
°C/W
LM1086
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