September 1999
LM1084
5A Low Dropout Positive Regulators
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.
Features
nAvailable in 3.3V, 5.0V, 12V and Adjustable Versions
nCurrent Limiting and Thermal Protection
n Output Current |
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5A |
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n Industrial Temperature Range |
−40ÊC to 125ÊC |
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n |
Line Regulation |
0.015% |
(typical) |
n |
Load Regulation |
0.1% |
(typical) |
Applications
nPost Regulator for Switching DC/DC Conveter
nHigh Efficiency Linear Regulators
nBattery Charger
Connection Diagrams
TO-220 |
TO-263 |
DS100946-36
Top View
DS100946-35
Top View
Basic Functional Diagram, Adjustable Version
DS100946-65
Regulators Positive Dropout Low 5A LM1084
© 1999 National Semiconductor Corporation |
DS100946 |
www.national.com |
Ordering Information
Package |
Temperature Range |
Part Number |
Transport Media |
NSC Drawing |
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3-lead TO-263 |
−40ÊC to +125ÊC |
LM1084IS-ADJ |
Rails |
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LM1084ISX-ADJ |
Tape and Reel |
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LM1084IS-12 |
Rails |
TS3B |
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LM1084ISX-12 |
Tape and Reel |
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LM1084IS-3.3 |
Rails |
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LM1084ISX-3.3 |
Tape and Reel |
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LM1084IS-5.0 |
Rails |
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LM1084ISX-5.0 |
Tape and Reel |
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3-lead TO-220 |
−40ÊC to + 125ÊC |
LM1084IT-ADJ |
Rails |
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LM1084IT-12 |
Rails |
T03B |
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LM1084IT-3.3 |
Rails |
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LM1084IT-5.0 |
Rails |
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Simplified Schematic
DS100946-34
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2 |
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
LM1084-ADJ |
29V |
LM1084-12 |
18V |
LM1084-3.3 |
27V |
LM1084-5.0 |
25V |
Power Dissipation (Note 2) |
Internally Limited |
Junction Temperature (TJ)(Note 3) |
150ÊC |
Storage Temperature Range |
-65ÊC to 150ÊC |
Lead Temperature |
260ÊC, to 10 sec |
ESD Tolerance (Note 4) |
2000V |
Operating Ratings (Note 1)
Junction Temperature Range (TJ) (Note 3)
Control Section |
−40ÊC to 125ÊC |
Output Section |
−40ÊC to 150ÊC |
Electrical Characteristics
Typicals and limits appearing in normal type apply for TJ = 25ÊC. Limits appearing in Boldface type apply over the entire junction temperature range for operation.
Symbol |
Parameter |
Conditions |
Min |
Typ |
Max |
Units |
(Note |
(Note |
(Note |
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6) |
5) |
6) |
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VREF |
Reference |
LM1084-ADJ |
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Voltage |
IOUT = 10mA, VIN−V OUT = 3V |
1.238 |
1.250 |
1.262 |
V |
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10mA ≤IOUT ≤ IFULL LOAD,1.5V ≤ (VIN−V OUT) ≤ |
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1.225 |
1.250 |
1.270 |
V |
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25V |
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(Note 7) |
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VOUT |
Output Voltage |
LM1084-3.3 |
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(Note 7) |
IOUT = 0mA, VIN = 8V |
3.270 |
3.300 |
3.330 |
V |
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0 ≤ IOUT ≤IFULL LOAD, 4.8V≤ VIN ≤15V |
3.235 |
3.300 |
3.365 |
V |
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LM1084-5.0 |
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IOUT = 0mA, VIN = 8V |
4.950 |
5.000 |
5.050 |
V |
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0 ≤ IOUT ≤ IFULL LOAD, 6.5V ≤ VIN ≤ 20V |
4.900 |
5.000 |
5.100 |
V |
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LM1084-12 |
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IOUT = 0mA, VIN = 15V |
11.880 |
12.000 |
12.120 |
V |
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0 ≤ IOUT ≤ IFULL LOAD, 13.5V ≤ VIN ≤ 25V |
11.760 |
12.000 |
12.240 |
V |
VOUT |
Line Regulation |
LM1084-ADJ |
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0.015 |
0.2 |
% |
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(Note 8) |
IOUT =10mA, 1.5V≤ (VIN-VOUT) ≤ 15V |
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0.035 |
0.2 |
% |
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LM1084-3.3 |
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0.5 |
6 |
mV |
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IOUT = 0mA, 4.8V ≤ VIN ≤ 15V |
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1.0 |
6 |
mV |
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LM1084-5.0 |
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0.5 |
10 |
mV |
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IOUT = 0mA, 6.5V ≤ VIN ≤ 20V |
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1.0 |
10 |
mV |
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LM1084-12 |
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1.0 |
25 |
mV |
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I OUT =0mA, 13.5V ≤ VIN ≤ 25V |
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2.0 |
25 |
mV |
VOUT |
Load Regulation |
LM1084-ADJ |
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0.1 |
0.3 |
% |
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(Note 8) |
(VIN-V OUT) = 3V, 10mA ≤ IOUT ≤ IFULL LOAD |
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0.2 |
0.4 |
% |
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LM1084-3.3 |
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3 |
15 |
mV |
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VIN = 5V, 0 ≤ IOUT ≤ IFULL LOAD |
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7 |
20 |
mV |
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LM1084-5.0 |
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5 |
20 |
mV |
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VIN = 8V, 0 ≤ IOUT ≤ IFULL LOAD |
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10 |
35 |
mV |
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LM1084-12 |
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12 |
36 |
mV |
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VIN = 15V, 0 ≤ IOUT ≤ IFULL LOAD |
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24 |
72 |
mV |
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Dropout Voltage |
LM1084-3.3/5/12/ADJ |
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(Note 9) |
VREF = 1%, IOUT = 5A |
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1.3 |
1.5 |
V |
3 |
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Electrical Characteristics (Continued)
Typicals and limits appearing in normal type apply for TJ = 25ÊC. Limits appearing in Boldface type apply over the entire junction temperature range for operation.
Symbol |
Parameter |
Conditions |
Min |
Typ |
Max |
Units |
(Note |
(Note |
(Note |
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6) |
5) |
6) |
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ILIMIT |
Current Limit |
LM1084-ADJ |
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VIN−V OUT = 5V |
5.5 |
8.0 |
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A |
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VIN−V OUT = 25V |
0.3 |
0.6 |
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A |
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LM1084-3.3 |
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VIN = 8V |
5.5 |
8.0 |
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A |
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LM1084-5.0 |
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VIN = 10V |
5.5 |
8.0 |
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A |
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LM1084-12 |
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VIN = 17V |
5.5 |
8.0 |
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A |
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Minimum Load |
LM1084-ADJ |
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Current (Note |
VIN −V OUT = 25V |
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10) |
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5 |
10.0 |
mA |
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Quiescent |
LM1084-3.3 |
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Current |
VIN = 18V |
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5.0 |
10.0 |
mA |
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LM1084-5.0 |
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VIN ≤ 20V |
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5.0 |
10.0 |
mA |
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LM1084-12 |
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VIN ≤ 25V |
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5.0 |
10.0 |
mA |
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Thermal |
TA = 25ÊC, 30ms Pulse |
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0.003 |
0.015 |
%/W |
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Regulation |
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Ripple Rejection |
fRIPPLE = 120Hz, = COUT = 25µF Tantalum, IOUT |
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= 5A |
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LM1084-ADJ, CADJ, = 25µF, (VIN−V O) = 3V |
60 |
75 |
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dB |
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LM1084-3.3, VIN = 6.3V |
60 |
72 |
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dB |
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LM1084-5.0, VIN = 8V |
60 |
68 |
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dB |
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LM1084-12 VIN = 15V |
54 |
60 |
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dB |
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Adjust Pin |
LM1084 |
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55 |
120 |
µA |
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Current |
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Adjust Pin |
10mA ≤ IOUT ≤ IFULL LOAD, |
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0.2 |
5 |
µA |
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Current Change |
1.5V ≤ VIN−V OUT ≤ 25V |
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Temperature |
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0.5 |
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% |
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Stability |
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Long Term |
TA =125ÊC, 1000Hrs |
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Stability |
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0.3 |
1.0 |
% |
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RMS Output |
10Hz ≤ f≤ 10kHz |
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0.003 |
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% |
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Noise |
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(% of VOUT) |
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Thermal |
3-Lead TO-263: Control Section/Output Section |
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0.65/2.7 |
ÊC/W |
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Resistance |
3-Lead TO-220: Control Section/Output Section |
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0.65/2.7 |
ÊC/W |
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Junction-to-Case |
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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 TJ(max) , θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max)±T A)/θJA. All numbers apply for packages soldered directly into a PC board. Refer to Thermal Considerations in the Application Notes.
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: IFULLLOAD is defined in the current limit curves. The IFULLLOAD Curve defines the current limit as a function of input-to-output voltage. Note that 30W power 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.
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4 |
Electrical Characteristics (Continued)
Note 10: The minimum output current required to maintain regulation.
5 |
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