LT1085MK-12 [Linear]
3A, 5A, 7.5A Low Dropout Positive Fixed Regulators; 3A，5A ， 7.5A低压差正，固定式稳压器
| 型号： | LT1085MK-12 |
| 厂家： | 
Linear |
| 描述： | 3A, 5A, 7.5A Low Dropout Positive Fixed Regulators |
| 文件： | 总12页 (文件大小：289K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1083/84/85 Fixed
3A, 5A, 7.5A Low Dropout
Positive Fixed Regulators
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FEATURES
DESCRIPTION
■
Three-Terminal 3.3V, 3.6V, 5V and 12V
Output Current of 3A, 5A or 7.5A
Operates Down to 1V Dropout
The LT1083 series of positive adjustable regulators are
designedtoprovide3A, 5Aand7.5Awithhigherefficiency
than currently available devices. All internal circuitry is
■
■
■
Guaranteed Dropout Voltage at Multiple Current Levels designedtooperatedownto1Vinputtooutputdifferential
■
■
■
■
Line Regulation: 0.015%
and the dropout voltage is fully specified as a function of
load current. Dropout is guaranteed at a maximum of 1.5V
at maximum output current, decreasing at lower load
currents. On-chip trimming adjusts the output voltage to
1%. Current limit is also trimmed, minimizing the stress
on both the regulator and power source circuitry under
overload conditions.
Load Regulation: 0.1%
100% Thermal Limit Functional Test
Adjustable Versions Available
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APPLICATIONS
■
High Efficiency Linear Regulators
The 1083 series devices are pin compatible with older
three-terminal regulators. A 10µF output capacitor is
required on these new devices; however, this is usually
included in most regulator designs.
■
Post Regulators for Switching Supplies
■
Constant Current Regulators
Battery Chargers
■
DEVICE
OUTPUT CURRENT*
Unlike PNP regulators, where up to 10% of the output
current is wasted as quiescent current, the LT1083 quies-
cent current flows into the load, increasing efficiency.
LT1083
LT1084
LT1085
7.5 Amps
5.0 Amps
3.0 Amps
*For a 1.5A low dropout regulator see the LT1086 data sheet.
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TYPICAL APPLICATION
5V, 7.5A Regulator
Dropout Voltage vs Output Current
2
V
IN
≥ 6.5V
5V AT 7.5A
LT1083-5
+
+
22µF*
TANTALUM
10µF
1
0
*REQUIRED FOR STABILITY
LT1083/4/5 TA01
0
I
/2
I
FULL LOAD
FULL LOAD
OUTPUT CURRENT (A)
1083/4/5 TA02
1
LT1083/84/85 Fixed
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ABSOLUTE MAXIMUM RATINGS
Power Dissipation............................... Internally Limited
Input Voltage (Note 1) ............................................. 30V
Operating Input Voltage
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
Note 1: Although the devices maximum operating voltage is limited, (20V
for a 3V, 5V device, and 25V for a 12V device) the devices are guaranteed
to withstand transient input voltages up to 30V. For input voltages greater
than the maximum operating input voltage some degradation of
specifications will occur. For input/output voltage differentials greater than
15V, a minimum external load of 5mA is required to maintain regulation.
3.3V, 3.6V Devices ............................................ 20V
5V Devices ........................................................ 20V
12V Devices ...................................................... 25V
Operating Junction Temperature Range
“C” Grades
Control Section ............................... 0°C to 125°C
Power Transistor............................. 0°C to 150°C
“M” Grades
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PRECONDITIONING
100% Thermal Limit Functional Test.
Control Section ...........................–55°C to 150°C
Power Transistor.........................–55°C to 200°C
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PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
ORDER PART NUMBER
FRONT VIEW
CASE IS
OUTPUT
V
IN
TAB IS
OUTPUT
2
1
LT1084MK-5
LT1084MK-12
LT1085CK-5
LT1085CK-12
LT1085MK-5
LT1085MK-12
LT1083CK-5
LT1083CK-12
LT1083MK-5
LT1083MK-12
LT1084CK-5
LT1084CK-12
LT1083CP-5
LT1083CP-12
LT1084CP-5
LT1084CP-12
3
2
1
V
V
IN
OUT
GND
GND
P PACKAGE
3-LEAD TO-3P PLASTIC
K PACKAGE
2-LEAD TO-3 METAL CAN
θJA = 45°C/W
θJA = 35°C/W
FRONT VIEW
FRONT VIEW
TAB IS
OUTPUT
LT1084CT-3.3
3
2
1
V
V
IN
LT1084CT-5
LT1084CT-12
LT1085CT-3.3
LT1085CT-3.6
LT1085CT-5
LT1085CT-12
LT1085CM-3.3
LT1085CM-3.6
TAB IS
OUTPUT
3
2
1
V
IN
OUT
V
OUT
GND
GND
M PACKAGE
3-LEAD PLASTIC DD
T PACKAGE
3-LEAD PLASTIC TO-220
θJA = 30°C/W*
*WITH PACKAGE SOLDERED TO 0.52IN2
COPPER AREA OVER BACKSIDE GROUND
PLANE OR INTERNAL POWER PLANE. θJA CAN
VARY FROM 20°C/W TO > 40°C/W DEPENDING
ON MOUNTING TECHNIQUE.
θJA = 50°C/W
Consult factory for Industrial grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Voltage
LT1084-3.3
I
= 0mA, T = 25°C, V = 8V (K Package Only)
3.270 3.300 3.330
3.235 3.300 3.365
3.270 3.300 3.330
3.235 3.300 3.365
V
V
V
V
V
V
V
OUT
J
IN
0 ≤ I
V
≤ 5A, 4.8V ≤ V ≤ 15V (Note 8)
●
●
●
OUT
IN
LT1085-3.3
LT1085-3.6
= 5V, I
= 0mA, T = 25°C (K Package Only)
IN
OUT
J
4.8V ≤ V ≤ 15V, 0 ≤ I
V
5V ≤ V ≤ 15V, 0 ≤ I
5V ≤ V ≤ 15V, 0 ≤ I
≤ 3A (Note 8)
IN
OUT
= 5V, I
IN
= 0mA, T = 25°C (K Package Only)
3.564 3.600 3.636
IN
OUT
J
≤ 3A (Note 8)
3.500
3.528
3.672
3.672
OUT
OUT
≤ 3A, TJ ≥ 0°C (Note 8)
IN
2
LT1083/84/85 Fixed
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Voltage
LT1085-3.6
5V ≤ V ≤ 15V, 0 ≤ I
≤ 2.5A (Note 8)
J
●
3.528
3.350
3.450
3.528
3.672
3.672
3.672
3.672
V
V
V
V
IN
OUT
V
IN
V
IN
V
IN
= 4.75V, I
= 4.75V, I
= 4.75V, I
= 3A, T ≥ 0°C
= 2.5A, T ≥ 0°C
= 1.5A, T > 0°C
OUT
OUT
OUT
J
J
LT1083/4/5-5
LT1083/4/5-12
LT1084-3.3
I
= 0mA, T = 25°C, V = 8V (K Package Only)
4.950 5.000 5.050
4.900 5.000 5.100
11.880 12.000 12.120
11.760 12.000 12.240
V
V
V
V
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
OUT
J
IN
0 ≤ I
I
0 ≤ I
I
≤ I
, 6.5V ≤ V ≤ 20V (Notes 3, 5, 6, 8)
FULLOAD IN
OUT
= 0mA, T = 25°C, V = 15V (K Package Only)
OUT
J
IN
≤ I
, 13.5V ≤ V ≤ 25V (Notes 3, 5, 6, 8)
FULLOAD IN
OUT
Line Regulation
= 0mA, T = 25°C, 4.8V ≤ V ≤ 15V
0.5
1.0
6
6
OUT
J
IN
●
●
●
●
●
●
●
●
●
LT1085-3.3
4.8V ≤ V ≤ 15V, I
= 0mA, T = 25°C
0.5
1.0
6
6
IN
OUT
J
LT1085-3.6
4.8V ≤ V ≤ 15V, I
= 0mA, T = 25°C
0.5
1.0
6
6
IN
OUT
J
LT1083/4/5-5
LT1083/4/5-12
LT1084-3.3
I
I
= 0mA, T = 25°C, 6.5V ≤ V ≤ 20V (Notes 1, 2)
0.5
1.0
10
10
OUT
OUT
J
IN
= 0mA, T = 25°C, 13.5V ≤ V ≤ 25V (Notes 1, 2)
1.0
2.0
25
25
J
IN
Load Regulation
V
V
V
V
V
= 5V, 0 ≤ I
≤ 5A, T = 25°C
3
7
15
20
IN
IN
IN
IN
IN
OUT
OUT
J
LT1085-3.3
= 5V, 0 ≤ I
≤ 3A, T = 25°C
3
7
15
20
J
LT1085-3.6
= 5.25V, 0 ≤ I
≤ 3A, T = 25°C
3
7
15
20
OUT
J
LT1083/4/5-5
LT1083/4/5-12
= 8V, 0 ≤ I
≤ I
T = 25°C (Notes 1, 2, 3, 5)
FULLLOAD, J
5
10
20
35
OUT
= 15V, 0 ≤ I
≤ I
T = 25°C (Notes 1, 2, 3, 5)
FULLLOAD, J
12
24
36
72
OUT
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
Dropout Voltage
Current Limit
LT1084/5-3.3
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
LT1083-5
LT1083-12
LT1084-3.3
LT1084-5
∆V
∆V
∆V
∆V
= 33mV, I
= 36mV, I
= 50mV, I
= I
= I
= I
(Notes 4, 5)
(Notes 4, 5)
(Notes 4, 5)
1.3
1.3
1.3
1.3
9.5
9.5
6.5
6.5
6.5
4.0
4.0
4.0
5.0
5.0
5.0
5.0
5.0
1.5
1.5
1.5
1.5
V
V
V
V
A
A
A
A
A
A
A
A
mA
mA
mA
mA
mA
OUT
OUT
OUT
OUT
OUT
FULL LOAD
FULL LOAD
FULL LOAD
OUT
OUT
= 120mV, I
= I
(Notes 4, 5)
OUT
FULL LOAD
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
= 10V
= 17V
= 8V
8.0
8.0
5.5
5.5
5.5
3.2
3.2
3.2
= 10V
= 17V
= 8V
= 10V
= 17V
= 18V
= 18V
= 18V
≤ 20V
≤ 25V
LT1084-12
LT1085-3.3/3.6
LT1085-5
LT1085-12
Quiescient Current
LT1084-3.3
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
10.0
10.0
10.0
10.0
10.0
Thermal Regulation
Ripple Rejection
LT1083-5/12
LT1084-3.3/5/12
LT1085-3.3/3.6/5/12
T = 25°C, 30ms pulse
0.002 0.010
0.003 0.015
0.004 0.020
%/W
%/W
%/W
A
f = 120Hz, C
LT1084-3.3
= 25µF Tantalum, I
= I
OUT FULLLOAD
= 25µF Tantalum, I
OUT
f = 120Hz, C
= 5A, V = 6.3V
●
60
72
dB
OUT
OUT
IN
3
LT1083/84/85 Fixed
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Ripple Rejection
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
f = 120Hz, C
f = 120Hz, C
= 25µF Tantalum, V = 6.3V, I
= 3A
= 3A
●
●
●
●
60
60
60
54
72
72
68
60
dB
dB
dB
dB
OUT
IN
OUT
OUT
= 25µF Tantalum, V = 6.6V, I
OUT
IN
V
IN
V
IN
= 8V (Note 5)
= 15V (Note 5)
Temperature Stability
Long Term Stability
RMS Output Noise
●
0.5
0.03
%
%
T = 125°C, 1000 Hrs.
1.0
A
T = 25°C,
A
(% of V
)
10Hz = ≤ f ≤ 10kHz
0.003
%
OUT
Thermal Resistance
Junctrion-to-Case
Control Circuitry/Power Transistor (See Applications Information)
LT1083
K Package
P Package
0.6/1.6
0.5/1.6
°C/W
°C/W
LT1084
K Package
P Package
T Package
0.75/2.3
0.65/2.3
0.65/2.7
°C/W
°C/W
°C/W
LT1085
K Package
T Package
DD Package
0.9/3.0
0.7/3.0
0.7/3.0
°C/W
°C/W
°C/W
The ● denotes the specifications which apply over the full operating
temperature range.
Note 1: See thermal regulation specifications for changes in output voltage
due to heating effects. Load and line regulation are measured at a constant
junction temperature by low duty cycle pulse testing.
input to output voltage. Note that the 60W power dissipation for the
LT1083 (45W for the LT1084 (K, P), 30W for the LT1084 (T), 30W for the
LT1085) is only achievable over a limited range of input to output voltage.
Note 4: Dropout voltage is specified over the full output current range of
the device. Test points and limits are shown on the Dropout Voltage curve.
Note 2: Line and load regulation are guaranteed up to the maximum power
dissipation (60W for the LT1083, 45W for the LT1084 (K, P), 30W for the
LT1084 (T) and 30W for the LT1085). 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 5: For LT1083 I
is 5A for –55°C ≤ T ≤ –40°C and 7.5A for
J
FULL LOAD
T ≥ – 40°C.
J
Note 6: 1.7V ≤ (V – V ) ≤ 25V for LT1084 at –55°C ≤ T ≤ – 40°C.
IN
OUT
J
Note 7: Dropout voltage 1.7V maximum for LT1084 at –55 ≤ T ≤ –40°C.
Note 8: Full load current is not available at all input-output voltages.
See Notes 2,3,5.
J
Note 3: I
is defined in the current limit curves. The I
FULL LOAD
FULLLOAD
curve is defined as the minimum value of current limit as a function of
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TYPICAL PERFORMANCE CHARACTERISTICS
LT1083 Dropout Voltage
LT1083 Short-Circuit Current
LT1083 Load Regulation
2
12
10
8
0.10
0.05
INDICATES GUARANTEED TEST POINT
∆I = 7.5A
–40°C ≤ T ≤ 150°C
25°C
J
0°C ≤ T ≤ 125°C
J
150°C
0
1
–0.05
–0.10
–0.15
–0.20
6
T
= 150°C
J
–55°C
4
2
0
T
= 25°C
J
I
FULL LOAD
GUARANTEED
T
J
= –55°C
0
75 100
–50 –25
0
25 50
125 150
0
1
2
3
4
5
6
7
8
9
10
20
30
35
0
5
10
15
25
TEMPERATURE (°C)
OUTPUT CURRENT (A)
INPUT/OUTPUT DIFFERENTIAL (V)
LT1083/4/5 FIXED G03
LT1083/4/5 FIXED G01
LT1083/4/5 FIXED G02
4
LT1083/84/85 Fixed
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TYPICAL PERFORMANCE CHARACTERISTICS
LT1084 Dropout Voltage
LT1084 Short Circuit Current
LT1084 Load Regulation
10
9
8
7
6
5
4
3
2
1
0
0.10
2
INDICATES GUARANTEED TEST POINT
∆I = 5A
0.05
0
–55°C ≤ T ≤ 150°C
J
0°C ≤ T ≤ 125°C
J
150°C
25°C
–0.05
–0.10
–0.15
–0.20
1
T
= –55°C
J
–55°C
T
= 25°C
J
T
= 150°C
J
I
FULL LOAD
GUARANTEED
0
2
75 100
0
10
INPUT/OUTPUT DIFFERENTIAL (V)
15
20
25
30
35
–50 –25
0
25 50
125 150
5
0
1
3
4
5
6
2
TEMPERATURE (°C)
OUTPUT CURRENT (A)
LT1083/4/5 FIXED G06
LT1083/4/5 FIXED G05
LT1083/4/5 FIXEDG04
LT1085 Dropout Voltage
LT1085 Short-Circuit Current
LT1085 Load Regulation
6
5
4
3
0.10
0.05
INDICATES GUARANTEED TEST POINT
∆I = 3A
–55°C ≤ T ≤ 150°C
J
0°C ≤ T ≤ 125°C
J
25°C
0
150°C
1
0
–0.05
–0.10
–0.15
–0.20
T
J
= –55°C
–55°C
T
= 25°C
J
T
J
= 150°C
2
1
0
I
FULL LOAD
GUARANTEED
20
30
35
0
5
10
15
25
0
2
3
75 100
125 150
1
4
–50 –25
0
25 50
OUTPUT CURRENT (A)
TEMPERATURE (°C)
INPUT/OUTPUT DIFFERENTIAL (V)
LT1083/4/5 FIXED G08
LT1083/4/5 FIXED G07
LT1083/4/5 FIXED G09
LT1083/4/5-5 Ripple Rejection
vs Current
LT1083/4/5-5 Ripple Rejection
Temperature Stability
2.0
1.0
80
70
60
50
100
90
80
70
60
50
40
30
20
10
0
V
≤ 3V
P-P
V
RIPPLE
RIPPLE
≤ 0.5V
P-P
f
= 120Hz
RIPPLE
R
V
(V – V ) ≥ 3V
IN
OUT
≤ 3V
P-P
f
= 20kHz
RIPPLE
R
(V – V ) ≥ V
IN
OUT
DROPOUT
V
≤ 0.5V
P-P
40
30
0
–1.0
20
10
0
I
= I
OUT FULL LOAD
–2.0
10
100
1k
FREQUENCY (Hz)
10k
100k
50 75
TEMPERATURE (°C)
–50 –25
0
25
100 125 150
0
0.8
1.0
0.2
0.4
0.6
OUTPUT CURRENT (0 TO I
)
FULL LOAD
1083/4/5 FIXED G10
LT1183/4/5 FIXED G12
1083/4/5 FIXED G11
5
LT1083/84/85 Fixed
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TYPICAL PERFORMANCE CHARACTERISTICS
LT1083/4/5-12 Ripple Rejection
vs Current
LT1083 Maximum Power
Dissipation*
LT1083/4/5-12 Ripple Rejection
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
80
70
60
50
V
≤ 3V
P-P
V
RIPPLE
RIPPLE
≤ 0.5V
P-P
f
= 120Hz
RIPPLE
R
V
≤ 3V
P-P
LT1083MK
(V – V ) ≥ 3V
IN
OUT
f
= 20kHz
RIPPLE
R
40
30
V
≤ 0.5V
P-P
(V – V ) ≥ V
DROPOUT
IN
OUT
LT1083CP
20
10
0
I
= I
OUT FULL LOAD
LT1083CK
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
10
100
1k
FREQUENCY (Hz)
10k
100k
0
0.8
1.0
0.2
0.4
0.6
OUTPUT CURRENT (0 TO I
)
FULL LOAD
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
1083/4/5 FIXED G13
1083/4/5 FIXED G14
LT1083/4/5 FIXED G15
LT1085 Maximum Power
Dissipation*
LT1084 Maximum Power
Dissipation*
60
50
40
30
20
10
0
50
40
30
20
10
0
LT1084MK
LT1085MK
LT1084CT
LT1084CP
LT1085CT
LT1084CK
LT1085CK
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1083/4/5 FIXED G16
LT1083/4/5 FIXED G17
6
LT1083/84/85 Fixed
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BLOCK DIAGRAM
V
IN
+
–
THERMAL
LIMIT
GND
LT1083/4/5 BD
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APPLICATIONS INFORMATION
TheLT1083familyofthree-terminalregulatorsareeasyto
use and have all the protection features that are expected
in high performance voltage regulators. They are short
circuit protected, have safe area protection as well as
thermal shutdown to turn off the regulator should the
temperature exceed about 165°C.
teristics are available. These capacitors differ in capacitor
tolerance (sometimes ranging up to ±100%), equivalent
series resistance, and capacitance temperature coeffi-
cient. The 150µF or 22µF values given will ensure stability.
Normally, capacitor values on the order of 100µF are used
in the output of many regulators to ensure good transient
responsewithheavyloadcurrentchanges. Outputcapaci-
tance can be increased without limit and larger values of
output capacitance further improve stability and transient
response of the LT1083 regulators.
These regulators offer lower dropout voltage and more
precise reference tolerance. Further, the reference stabil-
ity with temperature is improved over older types of
regulators. The only circuit difference between using the
LT1083 family and older regulators is that they require an
output capacitor for stability.
Anotherpossiblestabilityproblemthatcanoccurinmono-
lithic IC regulators is current limit oscillations. These can
occur because in current limit the safe area protection
exhibits a negative impedance. The safe area protection
decreases the current limit as the input-to-output voltage
increases.That is the equivalent of having a negitive resis-
tancesinceincreasingvoltagecausescurrenttodecrease.
Negitiveresistanceduringcurrentlimitisnotuniquetothe
LT1083 series and has been present on all power IC
regulators. The value of negative resistance is a function
of how fast the current limit is folded back as input-to-
Stability
The circuit design used in the LT1083 family requires the
use of an output capacitor as part of the device frequency
compensation.Foralloperatingconditions,theadditionof
150µF aluminum electrolytic or a 22µF solid tantalum on
the output will ensure stability. Normally capacitors much
smaller than this can be used with the LT1083. Many
different types of capacitors with widely varying charac-
7
LT1083/84/85 Fixed
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APPLICATIONS INFORMATION
output voltage increases. This negative resistance can
react with capacitors or inductors on the input to cause
oscillations during current limiting. Depending on the
value of series resistance, the overall circuitry may end up
unstable. Since this is a system problem, it is not neces-
sarily easy to solve; however it does not cause any prob-
lems with the IC regulator and can usually be ignored.
voltage is rising, the input-to-output voltage differential
remains small allowing the regulator to supply large
output currents. With high input voltage a problem can
occurwhereinremovalofanoutputshortwillnotallowthe
output voltage to recover. Older regulators such as the
7800 series, also exhibited this phenomenon so it is not
unique to the LT1083.
The problem occurs with a heavy output load when the
input voltage is high and the output voltage is low, such as
immediately after a removal of a short. The load line for
such a load may intersect the output current curve at two
points. If this happens there are two stable output operat-
ing points for the regulator. With this double intersection
the power supply may need to be cycled down to zero and
brought up again to make the output recover.
Protection Diodes
In normal operation the LT1083 family does not need any
protection diodes, The internal diode between the input
and the output pins of the LT1083 family can handle
microsecond surge currents of 50A to 100A. Even with
large output capacitances it is very difficult to get those
valuesofsurgecurrentinnormaloperation.Onlywithhigh
value output capacitors, such as 1000µF to 5000µF and
with the input pin instantaneously shorted to ground, can
damageoccur. AcrowbarcircuitattheinputoftheLT1083
can generate those kinds of currents and a diode from
output-to-inputisthenrecommended.Normalpowersup-
ply cycling or even plugging and unplugging in the system
will not generate currents large enough to do any damage.
Ripple Rejection
In applications that require improved ripple rejection the
LT1083 series adjustable regulators should be used. With
LT1083 series adjustable regulators the addition of a
bypass capacitor from the adjust pin to ground will reduce
output ripple by the ratio of VOUT/1.25V. See LT1083
series adjustable regulator data sheet.
D1
1N4002
(OPTIONAL)
Load Regulation
Because the LT1083 is a three-terminal device, it is not
possible to provide true remote load sensing. Load regu-
lation will not be limited by the resistance of the wire
connecting the regulator to the load. The data sheet
specification for the load regulation is measured at the
bottom of the package. Negative side sensing is a true
Kelvin connection, with the ground pin of the device
returned to the negative side of the load.
V
V
OUT
IN
LT1083 OUT
ADJ
IN
+
C
OUT
150µF
LT1083/4/5 AI01
Overload Recovery
Like any of the IC power regulators, the LT1083 has safe
area protection. The safe area protection decreases the
current limit as input-to-output voltage increases and
keeps the power transistor inside a safe operating region
for all values of input-to-output voltage. The LT1083
protection is designed to provide some output current at
all values of input-to-output voltage up to the device
breakdown.
Thermal Considerations
The LT1083 series of regulators have internal power and
thermal limiting circuitry designed to protect the device
under overload conditions. For continuous normal load
conditions however, maximum junction temperature rat-
ings must not be exceeded. It is important to give careful
consideration to all sources of thermal resistance from
junction to ambient. This includes junction-to-case, case-
to-heat sink interface, and heat sink resistance itself. New
When power is first turned on, as the input voltage rises,
the output follows the input, allowing the regulator to start
up into very heavy loads. During the start-up, as the input
8
LT1083/84/85 Fixed
U
W U U
APPLICATIONS INFORMATION
thermal resistance specifications have been developed to
more accurately reflect device temperature and ensure
safe operating temperatures. The data section for these
newregulatorsprovidesaseparatethermalresistanceand
maximum junction temperature for both the Control Sec-
tion and the Power Section. Previous regulators, with a
single junction-to-case thermal resistance specification,
used an average of the two values provided here and
therefore could allow excessive junction temperatures
under certain conditions of ambient temperature and heat
sink resistance. To avoid this possibility, calculations
should be made for both sections to ensure that both
thermal limits are met.
For example, using a LT1083-5CK (TO-3, Commercial)
and assuming:
VIN(max continuous) = 9V, VOUT = 5V, IOUT = 6A,
TA = 75°C θHEAT SINK = 1°C/W,
θCASE-TO-HEAT SINK = 0.2°C/W for K package with
thermal compound.
Power dissipation under these conditions is equal to:
PD = (VIN – VOUT) (IOUT) = 24W
Junction temperature will be equal to:
TJ = TA + PD (θHEAT SINK + θCASE-TO-HEAT SINK + θJC)
For the Control Section:
TJ = 75°C + 24W (1°C/W + 0.2°C/W + 0.6°C/W) =
Junction-to-case thermal resistance is specified from the
ICjunctiontothebottomofthecasedirectlybelowthedie.
This is the lowest resistance path for heat flow. Proper
mounting is required to ensure the best possible thermal
flowfromthisareaofthepackagetotheheatsink.Thermal
compound at the case-to-heat sink interface is strongly
recommended. If the case of the device must be electroni-
cally isolated, a thermally conductive spacer can be used
as long as its added contribution to thermal resistance is
considered. Note that the case of all devices in this series
is electronically connected to the ouput.
118°C
118°C < 125°C = TJMAX (Control Section Commer-
cial Range)
For the Power Transistor:
TJ = 75°C + 24W (1°C/W + 0.2°C/W + 1.6°C/W) =
142°C
142°C < 150°C = TJMAX (Power Transistor Commer-
cial Range)
In both cases the junction temperature is below the
maximum rating for the respective sections, ensuring
reliable operation.
U
TYPICAL APPLICATIONS
High Efficiency Regulator
1mH
28V
INPUT
OUTPUT
IN
LT1083-5 OUT
GND
+
10,000µF
470Ω
1N914
10k
MR1122
28V
1k
1M
4N28
10k
+
–
LT1011
10k
28V
1N914
LT1083/4/5 TA03
9
LT1083/84/85 Fixed
U
TYPICAL APPLICATIONS
Paralleling Regulators
2 FEET #18 WIRE*
V
IN
IN
LT1083-5 OUT
IN
GND
V
= 5V
= 0A TO 15A
OUT
OUT
I
0.015Ω
LT1083-5 OUT
GND
*THE #18 WIRE ACTS
AS BALLAST RESISTANCE
INSURING CURRENT SHARING
BETWEEN BOTH DEVICES
LT1083/4/5 TA04
7.5A Regulator
T1
TRIAD
F-269U
L
1MH
C30B
12V
IN
LT1083-12 OUT
GND
0A TO 7.5A
20Ω
20Ω
+
+
T2
C1
50,000µF
3
4
2
1N4003
100µF
110VAC
LT1004-1.2
1
C30B
1N914
16k*
1N4003
1N4003
16k*
1µF
560Ω
15V
82k
10k
15k
8
–15V
4
11k*
200k
2
+
–
7
LT1011
0.1µF
3
1
NC
1N4148
100pF
15V
8
2N3904
10k
–15V
4
3
2
1
–
+
7
3
2
8
LM301A
LT1011
+
1% FILM RESISTOR
L-DALE TO-5 TYPE
T2-STANCOR 11Z-2003
*
6
1
–
7
15k
4
11k*
15V
–15V
REGULATOR WITH SCR PREREGULATOR TO
LOWER POWER DISSIPATION. ABOUT 1.7V
DIFFERENTIAL IS MAINTAINED ACROSS THE
LT1083 INDEPENDENT OF LOAD CURRENT.
15V
1µF
LT1083/4/5 TA05
10
LT1083/84/85 Fixed
U
TYPICAL APPLICATIONS
Adjusting Output Voltage
Regulator with Reference
V
IN
> 12V
V
IN
> 11.5V
10V
LT1085-5
LT1085-5
5V to 10V
+
+
+
+
100µF
100µF
10µF
10µF
5V
OUT
+
1k
LT1029
10µF*
LT1083/4/5 TA06
LT1083/4/5 TA07
*OPTIONAL IMPROVES RIPPLE REJECTION
Low Dropout Negative Supply
IN
LT1084-12 OUT
GND
V
IN
+
+
100µF
10,000µF
V
= –12V
OUT
FLOATING INPUT
LT1083/4/5 TA08
Battery Backed Up Regulated Supply
5.2V LINE
5.0V BATTERY
V
LT1084-5
IN
+
10µF
50Ω
SELECT
FOR
CHARGE
RATE
LT1084-5
+
+
6.5V
10µF
100µF
LT1083/4/5 TA09
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LT1083/84/85 Fixed
U
Dimension in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
M Package
3-Lead Plastic DD
T Package
3-Lead Plastic TO-220
0.380 – 0.420
(9.652 – 10.668)
0.139 – 0.153
(3.531 – 3.886)
DIA
0.169 – 0.185
(4.293 – 4.699)
0.401 ± 0.015
(10.185 ± 0.381)
0.079 – 0.135
(2.007 – 3.429)
0.060
(1.524)
0.035 – 0.055
0.175 ± 0.008
(0.889 – 1.397)
0.050 ± 0.008
(4.445 ± 0.203)
(1.270 ± 0.203)
15° TYP
0.235 – 0.270
(5.969 – 6.858)
+0.008
0.004
+0.012
–0.020
+0.305
–0.508
–0.004
0.331
0.059
(1.499)
TYP
0.560 – 0.650
(14.224 – 16.510)
+0.203
–0.102
0.102
(
)
8.407
(
)
0.105 ± 0.008
(2.667 ± 0.203)
1.005 – 1.080
(25.527 – 27.432)
0.100 ± 0.010
(2.5402 ± 0.254)
0.050 ± 0.008
(1.270 ± 0.203)
0.050 ± 0.012
(1.270 ± 0.305)
+0.012
–0.020
+0.305
–0.508
0.022 ± 0.005
(0.559 ± 0.127)
0.143
0.150
3.810
MIN
3.632
(
)
DD3 0693
0.015 – 0.025
(0.381 – 0.635)
0.027 – 0.037
(0.686 – 0.940)
0.079 – 0.115
(2.007 – 2.921)
0.050
(1.270)
TYP
0.090 – 0.110
(2.286 – 2.794)
T3 0693
K Package
2-Lead TO-3 Metal Can
P Package
3-Lead TO-3P Plastic
0.187 – 0.207
(4.75 – 5.26)
0.620 – 0.64O
(15.75 – 16.26)
0.760 – 0.775
(19.30 – 19.69)
0.320 – 0.350
(8.13 – 8.89)
0.060 – 0.080
(1.52 – 2.03)
MOUNTING HOLE
0.060 – 0.135
(1.524 – 3.429)
18° – 22°
0.115 – 0.145
(2.92 – 3.68)
DIA
0.170 – 0.2OO
(4.32 – 5.08)
0.830 – 0.870
(21.08 – 22.10)
0.420 – 0.480
(10.67 – 12.19)
EJECTOR PIN MARKS
0.105 – 0.125
(2.67 – 3.18)
DIA
0.580 – 0.6OO
(14.73 – 15.24)
0.038 – 0.043
(0.965 – 1.09)
1.177 – 1.197
(29.90 – 30.40)
3° – 7°
0.067 – 0.077
(1.70 – 1.96)
0.780 – 0.800
(19.81 – 20.32)
0.170
(4.32)
MAX
0.210 – 0.220
(5.33 – 5.59)
0.152 – 0.161
(3.86 – 4.09)
DIA
0.167 – 0.177
(4.24 – 4.49)
R TYP
0.425 – 0.435
(10.80 – 11.05)
0.215
(5.46)
BSC
0.087 – 0.102
(2.21 – 2.59)
0.042 – 0.052
(1.07 – 1.32)
0.495 – 0.525
(12.57 – 13.34)
0.655 – 0.675
(16.64 – 17.15)
0.020 – 0.040
(0.51 – 1.02)
K2 0592
P3 0892
0.113 – 0.123
(2.87 – 3.12)
0.074 – 0.084
(1.88 – 2.13)
LT/GP 06/94 5K REV B • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
12
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
© LINEAR TECHNOLOGY CORPORATION 1994
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