LT1085CK#TR [Linear]
IC VREG 1.2 V-15 V ADJUSTABLE POSITIVE LDO REGULATOR, 1.5 V DROPOUT, MBFM2, METAL CAN, TO-3, 2 PIN, Adjustable Positive Single Output LDO Regulator;
| 型号： | LT1085CK#TR |
| 厂家： | 
Linear |
| 描述： | IC VREG 1.2 V-15 V ADJUSTABLE POSITIVE LDO REGULATOR, 1.5 V DROPOUT, MBFM2, METAL CAN, TO-3, 2 PIN, Adjustable Positive Single Output LDO Regulator 局域网 输出元件 调节器 |
| 文件： | 总18页 (文件大小：199K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1083/LT1084/LT1085
7.5A, 5A, 3A Low Dropout
Positive Adjustable Regulators
FEATURES
DESCRIPTION
The LT®1083 series of positive adjustable regulators are
designedtoprovide7.5A, 5Aand3Awithhigherefficiency
than currently available devices. All internal circuitry is
n
3-Terminal Adjustable
n
Output Current of 3A, 5A or 7.5A
n
Operates Down to 1V Dropout
n
Guaranteed Dropout Voltage at Multiple Current Levels
Line Regulation: 0.015%
designedtooperatedownto1Vinput-to-outputdifferential
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 cur-
rents. On-chip trimming adjusts the reference voltage to
1%. Current limit is also trimmed, minimizing the stress
on both the regulator and power source circuitry under
overload conditions.
n
n
n
n
n
Load Regulation: 0.1%
100% Thermal Limit Functional Test
Fixed Versions Available
Available in 3-Lead Plastic TO-220, TO-3P and DD
Packages
The LT1083/LT1084/LT1085 devices are pin compatible
with older 3-terminal regulators. A 10μF output capacitor
isrequiredonthesenewdevices.However,thisisincluded
in most regulator designs.
APPLICATIONS
n
High Efficiency Linear Regulators
n
Post Regulators for Switching Supplies
n
Constant Current Regulators
Battery Chargers
Unlike PNP regulators, where up to 10% of the output cur-
rent is wasted as quiescent current, the LT1083 quiescent
current flows into the load, increasing efficiency.
n
DEVICE
OUTPUT CURRENT*
LT1083
LT1084
LT1085
7.5A
5.0A
3.0A
, LT, LTM and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*For a 1.5A low dropout regulator see the LT1086 data sheet.
TYPICAL APPLICATION
Dropout Voltage vs Output Current
2
5V, 7.5A Regulator
LT1083
ADJ
5V AT 7.5A
OUT
V
IN
≥ 6.5V
IN
121Ω
1%
+
1
0
+
10μF
10μF*
TANTALUM
365Ω
1%
*REQUIRED FOR STABILITY
1083/4/5 ADJ TA01
0
I
FULL LOAD
OUTPUT CURRENT
1083/4/5 ADJ TA02
108345fg
1
LT1083/LT1084/LT1085
(Note 1)
ABSOLUTE MAXIMUM RATINGS
Power Dissipation................................Internally Limited
Input-to-Output Voltage Differential
M-Grades: (OBSOLETE)
Control Section..............– 55°C to 150°C
Power Transistor............ –55°C to 200°C
Storage Temperature Range...................–65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
C-Grades ..............................................................30V
I-Grades................................................................30V
M-Grades (OBSOLETE).........................................35V
Operating Junction Temperature Range (Note 9)
C-Grades: Control Section.................. 0°C to 125°C
Power Transistor................ 0°C to 150°C
PRECONDITIONING
100% thermal shutdown functional test.
I-Grades: Control Section..............– 40°C to 125°C
Power Transistor............– 40°C to 150°C
PIN CONFIGURATION
TAB IS
FRONT VIEW
FRONT VIEW
OUTPUT
3
2
1
V
V
IN
3
2
1
V
V
TAB
IS
OUTPUT
IN
OUT
OUT
ADJ
ADJ
T PACKAGE
3-LEAD PLASTIC TO-220
P PACKAGE
3-LEAD PLASTIC TO-3P
θ
= 50°C/W
JA
θ
= 35°C/W
JA
BOTTOM VIEW
FRONT VIEW
CASE IS
OUTPUT
V
IN
3
2
1
V
V
IN
TAB
IS
OUTPUT
2
1
OUT
ADJ
M PACKAGE
3-LEAD PLASTIC DD
ADJ
K PACKAGE
θ
= 30°C/W*
JA
2-LEAD TO-3 METAL CAN
2
*WITH PACKAGE SOLDERED TO 0.5IN COPPER AREA OVER
θ
= 35°C/W
BACKSIDE GROUND PLANE OR INTERNAL POWER PLANE. θ CAN VARY
JA
JA
FROM 20°C/W TO >40°C/W DEPENDING ON MOUNTING TECHNIQUE
OBSOLETE PACKAGE
108345fg
2
LT1083/LT1084/LT1085
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1083CP#PBF
LT1083CP#TRPBF
LT1083CP
3-Lead Plastic TO-3P
3-Lead Plastic TO-3P
3-Lead Plastic TO-220
3-Lead Plastic TO-220
3-Lead Plastic TO-220
3-Lead Plastic TO-220
3-Lead Plastic DD
Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CP#PBF
LT1084CT#PBF
LT1084IT#PBF
LT1085CT#PBF
LT1085IT#PBF
LT1085CM#PBF
LT1085IM#PBF
LT1084CP#TRPBF
LT1084CT#TRPBF
LT1084IT#TRPBF
LT1085CT#TRPBF
LT1085IT#TRPBF
LT1085CM#TRPBF
LT1085IM#TRPBF
LT1084CP
LT1084CT
LT1084IT
LT1085CT
LT1085IT
LT1085CM
LT1085IM
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –40°C to 125°C
Power: –40°C to 150°C
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –40°C to 125°C
Power: –40°C to 150°C
Control: 0°C to 125°C
Power: 0°C to 150°C
3-Lead Plastic DD
Control: –40°C to 125°C
Power: –40°C to 150°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1083CP
LT1083CP#TR
LT1083CP
3-Lead Plastic TO-3P
Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CP
LT1084CT
LT1084IT
LT1085CT
LT1085IT
LT1085CM
LT1085IM
LT1083CK
LT1083MK
LT1084CK
LT1084MK
LT1085CK
LT1085MK
LT1084CP#TR
LT1084CT#TR
LT1084IT#TR
LT1085CT#TR
LT1085IT#TR
LT1085CM#TR
LT1085IM#TR
LT1083CK#TR
LT1083MK#TR
LT1084CK#TR
LT1084MK#TR
LT1085CK#TR
LT1085MK#TR
LT1084CP
LT1084CT
LT1084IT
LT1085CT
LT1085IT
LT1085CM
LT1085IM
LT1083CK
LT1083MK
LT1084CK
LT1084MK
LT1085CK
LT1085MK
3-Lead Plastic TO-3P
3-Lead Plastic TO-220
3-Lead Plastic TO-220
3-Lead Plastic TO-220
3-Lead Plastic TO-220
3-Lead Plastic DD
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –40°C to 125°C
Power: –40°C to 150°C
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –40°C to 125°C
Power: –40°C to 150°C
Control: 0°C to 125°C
Power: 0°C to 150°C
3-Lead Plastic DD
Control: –40°C to 125°C
Power: –40°C to 150°C
2-Lead TO-3 Metal Can
2-Lead TO-3 Metal Can
2-Lead TO-3 Metal Can
2-Lead TO-3 Metal Can
2-Lead TO-3 Metal Can
2-Lead TO-3 Metal Can
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –55°C to 150°C
Power: –55°C to 200°C
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –55°C to 150°C
Power: –55°C to 200°C
Control: 0°C to 125°C
Power: 0°C to 150°C
Control: –55°C to 150°C
Power: –55°C to 200°C
OBSOLETE PACKAGE
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
108345fg
3
LT1083/LT1084/LT1085
The l denotes the specifications which apply over the full operating
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at TA = 25°C.
PARAMETER
CONDITIONS
= 10mA, T = 25°C,
MIN
TYP
MAX
UNITS
Reference Voltage
I
OUT
J
(V – V ) = 3V
1.238
1.225
1.250
1.250
1.262
1.270
V
V
IN
OUT
OUT
10mA ≤ I
≤ I
FULL_LOAD
l
1.5V ≤ (V – V ) ≤ 25V (Notes 4, 6, 7)
IN
OUT
Line Regulation
I
= 10mA, 1.5V ≤ (V – V ) ≤ 15V, T = 25°C (Notes 2, 3)
0.015
0.035
0.2
0.2
%
%
LOAD
IN
OUT
J
l
l
l
M-Grade: 15V ≤ (V – V ) ≤ 35V (Notes 2, 3)
0.05
0.05
0.5
0.5
%
%
IN
OUT
C-, I-Grades: 15V ≤ (V – V ) ≤ 30V (Notes 2, 3)
IN
OUT
OUT
Load Regulation
Dropout Voltage
(V – V ) = 3V, 10mA ≤ I
(Notes 2, 3, 4, 6)
≤ I
FULL_LOAD
, T = 25°C
0.1
0.2
0.3
0.4
%
%
IN
OUT
J
l
l
ΔV = 1%, I
= I (Notes 5, 6, 8)
FULL_LOAD
1.3
1.5
V
REF
OUT
Current Limit
LT1083
l
l
l
l
l
l
(V – V ) = 5V
8.0
0.4
5.5
0.3
3.2
0.2
9.5
1.0
6.5
0.6
4.0
0.5
A
A
A
A
A
A
IN
OUT
(V – V ) = 25V
IN
OUT
LT1084
LT1085
(V – V ) = 5V
IN OUT
(V – V ) = 25V
IN
OUT
(V – V ) = 5V
IN
OUT
(V – V ) = 25V
IN
OUT
l
Minimum Load Current
(V – V ) = 25V
5
10
mA
IN
OUT
Thermal Regulation
LT1083
T = 25°C, 30ms Pulse
A
0.002
0.003
0.004
0.010
0.015
0.020
%/W
%/W
%/W
LT1084
LT1085
l
Ripple Rejection
f = 120Hz, C
= 25μF, C
= 25μF Tantalum
OUT
OUT
60
75
dB
ADJ
I
= I
, (V – V ) = 3V (Notes 6, 7, 8)
OUT
FULL_LOAD
IN
Adjust Pin Current
T = 25°C
55
μA
μA
J
l
l
l
120
5
Adjust Pin Current Change
Temperature Stability
10mA ≤ I
≤ I
, 1.5V ≤ (V – V ) ≤ 25V (Note 6)
0.2
0.5
μA
%
%
%
OUT
FULL_LOAD
IN
OUT
Long-Term Stability
T = 125°C, 1000 Hrs
A
0.3
1
RMS Output Noise (% of V
)
T = 25°C, 10Hz = ≤ f ≤ 10kHz
A
0.003
OUT
108345fg
4
LT1083/LT1084/LT1085
The l denotes the specifications which apply over the full operating
ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at TA = 25°C.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Thermal Resistance Junction-to-Case
LT1083
Control Circuitry/Power Transistor
K Package
0.6/1.6
0.5/1.6
0.75/2.3
0.65/2.3
0.65/2.7
0.9/3.0
0.7/3.0
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
P Package
LT1084
K Package
P Package
T Package
LT1085
K Package
M, T Package
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 5: 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 6: For LT1083 I
is 5A for –55°C ≤ T < – 40°C and 7.5A for
J
FULL_LOAD
Note 2: 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.
T ≥ –40°C.
J
Note 7: 1.7V ≤ (V – V ) ≤ 25V for LT1084 at –55°C ≤ T ≤ – 40°C.
Note 8: Dropout is 1.7V maximum for LT1084 at –55°C ≤ T ≤ –40°C.
IN
OUT
J
J
Note 3: 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 voltage
range.
Note 9: The LT1083/LT1084/LT1085 regulators are tested and specified
under pulse load conditions such that T ≅ T . The C-grade LT1083/
J
A
LT1084/LT1085 are 100% tested at 25°C.The I-grade LT1084/LT1085 are
guaranteed over the full –40°C to 125°C operating ambient temperature
range.
Note 4: I
is defined in the current limit curves. The I
FULL_LOAD
FULL_LOAD
curve is defined as the minimum value of current limit as a function of
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.
108345fg
5
LT1083/LT1084/LT1085
TYPICAL PERFORMANCE CHARACTERISTICS
LT1083
Dropout Voltage
LT1083
Short-Circut Current
LT1083
Load Regulation
12
10
8
0.10
0.05
2
INDICATES GUARANTEED TEST POINT
ΔI = 7.5A
–40°C ≤ T ≤ 150°C
J
25°C
0°C ≤ T ≤ 125°C
J
150°C
0
–0.05
–0.10
–0.15
–0.20
1
6
T
= 150°C
J
–55°C
4
2
0
T
= 25°C
J
T
= –55°C
J
I
FULL LOAD
GUARANTEED
10
INPUT/OUTPUT DIFFERENTIAL (V)
0
75 100
TEMPERATURE (°C)
–50 –25
0
25 50
125 150
0
1
2
3
4
5
6
7
8
9
10
20
30
35
0
5
15
25
OUTPUT CURRENT (A)
LT1083/4/5 ADJ G03
LT1083/4/5 ADJ G01
LT1083/4/5 ADJ G02
LT1084
Dropout Voltage
LT1084
LT1084
Short-Circut Current
Load Regulation
10
9
8
7
6
5
4
3
2
1
0
2
1
0
0.10
0.05
INDICATES GUARANTEED TEST POINT
ΔI = 5A
–55°C ≤ T ≤ 150°C
J
150°C
25°C
0°C ≤ T ≤ 125°C
J
0
–55°C
–0.05
–0.10
–0.15
–0.20
T
= –55°C
J
T
= 25°C
J
T
= 150°C
J
I
FULL LOAD
GUARANTEED
0
10
15
20
25
30
35
5
75 100
0
1
3
4
5
6
–50 –25
0
25 50
125 150
2
INPUT/OUTPUT DIFFERENTIAL (V)
TEMPERATURE (°C)
OUTPUT CURRENT (A)
LT1083/4/5 ADJ G05
LT1083/4/5 ADJ G04
LT1083/4/5 ADJ G06
LT1085
Dropout Voltage
LT1085
LT1085
Short-Circuit Current
Load Regulation
2
1
0
6
5
4
3
0.10
0.05
INDICATES GUARANTEED TEST POINT
ΔI = 3A
–55°C ≤ T ≤ 150°C
J
0°C ≤ T ≤ 125°C
J
25°C
0
150°C
–0.05
–0.10
–0.15
–0.20
T
= –55°C
J
T
= 25°C
–55°C
J
T
= 150°C
2
1
0
J
I
FULL LOAD
GUARANTEED
0
2
3
1
4
75 100
125 150
–50 –25
0
25 50
20
30
35
0
5
10
15
25
OUTPUT CURRENT (A)
TEMPERATURE (°C)
INPUT/OUTPUT DIFFERENTIAL (V)
LT1083/4/5 ADJ G07
LT1083/4/5 ADJ G09
LT1083/4/5 ADJ G08
108345fg
6
LT1083/LT1084/LT1085
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum Operating Current
Temperature Stability
Adjust Pin Current
10
9
8
7
6
5
4
3
2
1
0
100
90
80
70
60
50
40
30
20
10
0
1.27
1.26
1.25
1.24
1.23
T
= 150°C
J
T
= 25°C
J
T
= –55°C
J
75 100
–50 –25
0
25 50
125 150
0
10
15
20
25
30
35
–50 –25
0
25 50
75 100
125 150
5
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT/OUTPUT DIFFERENTIAL (V)
LT1083/4/5 ADJ G12
LT1083/4/5 ADJ G10
LT1083/4/5 ADJ G11
LT1083
Ripple Rejection
LT1083
Ripple Rejection vs Current
LT1083
Maximum Power Dissipation*
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
V
≤ 3V
P-P
V
f
= 120Hz
RIPPLE
RIPPLE
RIPPLE
R
V
≤ 0.5V
≤ 3V
P-P
P-P
(V – V ) ≥ 3V
IN
OUT
f
= 20kHz
RIPPLE
R
V
≤ 0.5V
P-P
LT1083MK
(V – V ) ≥ V
IN
OUT
DROPOUT
LT1083CP
LT1083CK
C
C
I
= 200μF AT FREQUENCIES < 60Hz
= 25μF AT FREQUENCIES > 60Hz
= 7A
V
C
C
= 5V
= 25μF
= 25μF
ADJ
ADJ
OUT
OUT
ADJ
OUT
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
10
100
1k
10k
100k
0
4
6
7
1
2
3
5
8
FREQUENCY (Hz)
OUTPUT CURRENT (A)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
1083/4/5 ADJ G13
1083/4/5 ADJ G14
LT1083/4/5 ADJ G15
LT1084
Ripple Rejection
LT1084
Ripple Rejection vs Current
LT1084
Maximum Power Dissipation*
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
60
f
= 120Hz
RIPPLE
V
≤ 3V
V
≤ 0.5V
RIPPLE P-P
R
RIPPLE
P-P
V
≤ 3V
P-P
50
(V – V ) ≥ 3V
IN
OUT
LT1084MK
f
= 20kHz
RIPPLE
R
40
V
≤ 0.5V
P-P
(V – V ) ≥ V
IN
OUT
DROPOUT
30
LT1084CT
LT1084CP
20
C
C
I
= 200μF AT FREQUENCIES < 60Hz
= 25μF AT FREQUENCIES > 60Hz
= 5A
V
C
C
= 5V
= 25μF
= 25μF
ADJ
ADJ
OUT
OUT
ADJ
OUT
10
0
LT1084CK
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
10
100
1k
10k
100k
0
4
1
2
3
5
FREQUENCY (Hz)
OUTPUT CURRENT (A)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
1083/4/5 ADJ G16
1083/4/5 ADJ G17
LT1083/4/5 ADJ G18
108345fg
7
LT1083/LT1084/LT1085
TYPICAL PERFORMANCE CHARACTERISTICS
LT1085
Ripple Rejection
LT1085
Ripple Rejection vs Current
LT1085
Maximum Power Dissipation*
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
50
40
30
20
10
0
V
≤ 3V
P-P
V
RIPPLE
RIPPLE
≤ 0.5V
P-P
f
= 120Hz
RIPPLE
R
(V – V ) ≥ 3V
IN
OUT
V
≤ 3V
P-P
LT1085MK
(V – V ) ≥ V
IN DROPOUT
f
V
= 20kHz
OUT
R
≤ 0.5V
RIPPLE
P-P
LT1085CT
LT1085CK
C
C
I
= 200μF AT FREQUENCIES < 60Hz
= 25μF AT FREQUENCIES > 60Hz
= 3A
V
= 5V
= 25μF
= 25μF
ADJ
ADJ
OUT
OUT
ADJ
OUT
C
C
10
100
1k
10k
100k
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
0
2.5
0.5
1.0
1.5
2.0
3.0
FREQUENCY (Hz)
OUTPUT CURRENT (A)
1083/4/5 ADJ G19
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
1083/4/5 ADJ G20
LT1083/4/5 ADJ G21
LT1084
Load Transient Response
LT1083
Load Transient Response
LT1085
Load Transient Response
0.6
0.4
0.2
0
0.6
0.3
C
ADJ
= 0
C
ADJ
= 0
0.4
0.2
0
0.2
0.1
0
C
ADJ
= 0
C
ADJ
= 1μF
C
= 1μF
C
= 1μF
ADJ
ADJ
–0.2
–0.4
8
–0.2
–0.4
–0.6
6
–0.1
–0.2
–0.3
3
C
C
= 1μF
OUT
IN
C
C
= 1μF
OUT
= 10μF TANTALUM
IN
C
C
= 1μF
OUT
IN
= 10μF TANTALUM
= 10μF TANTALUM
V
V
=10V
OUT
IN
6
=13V
PRELOAD=100mA
V
=10V
OUT
V
V
=10V
4
4
OUT
IN
2
V
=13V
IN
=13V
2
2
1
PRELOAD=100mA
PRELOAD=100mA
0
0
0
0
50
TIME (μs)
0
50
TIME (μs)
100
100
0
50
TIME (μs)
100
1083/4/5 ADJ G22
1083/4/5 ADJ G23
1083/4/5 ADJ G24
LT1083
Line Transient Response
LT1084
Line Transient Response
LT1085
Line Transient Response
150
100
50
60
40
60
40
C
ADJ
= 0
C
= 0
C
ADJ
= 0
ADJ
C
ADJ
= 1μF
C
= 1μF
ADJ
C
ADJ
= 1μF
20
20
0
0
0
–50
–100
–150
14
–20
–40
–60
14
–20
–40
–60
14
V
I
= 10V
V
I
C
C
= 10V
V
I
= 10V
OUT
IN
OUT
IN
IN
OUT
OUT
IN
= 0.2A
= 0.2A
= 0.2A
C
C
= 1μF TANTALUM
= 10μF TANTALUM
= 1μF TANTALUM
= 10μF TANTALUM
C
C
= 1μF TANTALUM
= 10μF TANTALUM
IN
OUT
IN
OUT
13
13
13
12
12
12
0
100
TIME (μs)
0
100
TIME (μs)
200
200
0
100
TIME (μs)
200
1083/4/5 ADJ G25
1083/4/5 ADJ G27
1083/4/5 ADJ G26
108345fg
8
LT1083/LT1084/LT1085
BLOCK DIAGRAM
V
IN
+
–
THERMAL
LIMIT
V
OUT
1083/4/5 ADJ BD
V
ADJ
APPLICATIONS INFORMATION
The LT1083 family of 3-terminal adjustable regulators is
easy to use and has all the protection features that are
expectedinhighperformancevoltageregulators.Theyare
short-circuit protected, and have safe area protection as
well as thermal shutdown to turn off the regulator should
the junction temperature exceed about 165°C.
on the output will ensure stability. Normally, capacitors
muchsmallerthanthiscanbeusedwiththeLT1083. Many
different types of capacitors with widely varying charac-
teristics are available. These capacitors differ in capacitor
tolerance (sometimes ranging up to 100%), equivalent
seriesresistance,andcapacitancetemperaturecoefficient.
The 150μF or 22μF values given will ensure stability.
These regulators are pin compatible with older 3-terminal
adjustable devices, offer lower dropout voltage and more
precisereferencetolerance.Further,thereferencestability
with temperature is improved over older types of regula-
tors. The only circuit difference between using the LT1083
family and older regulators is that this new family requires
an output capacitor for stability.
When the adjustment terminal is bypassed to improve the
ripple rejection, the requirement for an output capacitor
increases. The value of 22μF tantalum or 150μF aluminum
covers all cases of bypassing the adjustment terminal.
Without bypassing the adjustment terminal, smaller
capacitors can be used with equally good results and the
table below shows approximately what size capacitors are
needed to ensure stability.
Stability
Recommended Capacitor Values
The circuit design used in the LT1083 family requires the
use of an output capacitor as part of the device frequency
compensation.Foralloperatingconditions,theadditionof
a 150μF aluminium electrolytic or a 22μF solid tantalum
INPUT
OUTPUT
ADJUSTMENT
10μF
10μF
10μF Tantalum, 50μF Aluminum
22μF Tantalum, 150μF Aluminum
None
20μF
108345fg
9
LT1083/LT1084/LT1085
APPLICATIONS INFORMATION
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 capacitor further improve stability and transient
response of the LT1083 regulators.
pininstantaneouslyshortedtoground,candamageoccur.
A crowbar circuit at the input of the LT1083 can generate
thosekindsofcurrents, andadiodefromoutputtoinputis
then recommended. Normal power supply cycling or even
plugging and unplugging in the system will not generate
current large enough to do any damage.
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 volt-
age increases. That is the equivalent of having a negative
resistance since increasing voltage causes current to
decrease. Negative resistance during current limit is not
unique to the LT1083 series and has been present on all
power IC regulators. The value of the negative resistance
is a function of how fast the current limit is folded back as
input-to-outputvoltageincreases.Thisnegativeresistance
canreactwithcapacitorsorinductorsontheinputtocause
oscillationduringcurrentlimiting. Dependingonthevalue
of series resistance, the overall circuitry may end up un-
stable. Since this is a system problem, it is not necessarily
easy to solve; however, it does not cause any problems
with the IC regulator and can usually be ignored.
The adjustment pin can be driven on a transient basis
25V, with respect to the output without any device deg-
radation. Of course, as with any IC regulator, exceeding
the maximum input to output voltage differential causes
the internal transistors to break down and none of the
protection circuitry is functional.
D1
1N4002
(OPTIONAL)
IN
OUT
LT1083
ADJ
V
OUT
V
IN
+
C
OUT
150μF
R1
R2
+
C
ADJ
10μF
1083/4/5 ADJ F00
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.
Protection Diodes
In normal operation, the LT1083 family does not need
any protection diodes. Older adjustable regulators re-
quired protection diodes between the adjustment pin and
the output and from the output to the input to prevent
overstressing the die. The internal current paths on the
LT1083 adjustment pin are limited by internal resistors.
Therefore, even with capacitors on the adjustment pin, no
protection diode is needed to ensure device safety under
short-circuit conditions.
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
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
occur wherein removal of an output short will not allow
the output voltage to recover. Older regulators, such as
the 7800 series, also exhibited this phenomenon, so it is
not unique to the LT1083.
Diodes between input and output are usually not needed.
The internal diode between the input and the output pins
of the LT1083 family can handle microsecond surge cur-
rentsof50Ato100A. Evenwithlargeoutputcapacitances,
it is very difficult to get those values of surge currents
in normal operations. Only with a high value of output
capacitors, such as 1000μF to 5000μF and with the input
108345fg
10
LT1083/LT1084/LT1085
APPLICATIONS INFORMATION
The problem occurs with a heavy output load when the
input voltage is high and the output voltage is low, such
as immediately after 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.
IN
OUT
LT1083
ADJ
V
OUT
V
IN
V
R1
R2
REF
I
ADJ
50μA
R2
R1
V
= V
1 +
+ I
ADJ
R2
OUT
REF
(
)
1083/4/5 ADJ F01
Figure 1. Basic Adjustable Regulator
Ripple Rejection
Load Regulation
The typical curves for ripple rejection reflect values for a
bypassed adjustment pin. This curve will be true for all
values of output voltage. For proper bypassing and ripple
rejection approaching the values shown, the impedance
of the adjust pin capacitor at the ripple frequency should
be less than the value of R1, (normally 100Ω to 120Ω).
The size of the required adjust pin capacitor is a function
of the input ripple frequency. At 120Hz the adjust pin
capacitor should be 25μF if R1 = 100Ω. At 10kHz only
0.22μF is needed.
Because the LT1083 is a 3-terminal device, it is not pos-
sible to provide true remote load sensing. Load regulation
will be limited by the resistance of the wire connecting
the regulator to the load. The data sheet specification for
load regulation is measured at the bottom of the package.
Negative side sensing is a true Kelvin connection, with the
bottom of the output divider returned to the negative side
of the load. Although it may not be immediately obvious,
best load regulation is obtained when the top of the resis-
tor divider R1 is connected directly to the case not to the
load. This is illustrated in Figure 2. If R1 were connected
to the load, the effective resistance between the regulator
and the load would be:
Forcircuitswithoutanadjustpinbypasscapacitor,theripple
rejection will be a function of output voltage. The output
ripple will increase directly as a ratio of the output voltage
to the reference voltage (V /V ). For example, with
R2+R1
⎞
OUT REF
⎛
R •
,R =Parasitic LineResistance
P
⎜
⎝
⎟
P
the output voltage equal to 5V and no adjust pin capacitor,
the output ripple will be higher by the ratio of 5V/1.25V
or four times larger. Ripple rejection will be degraded by
12dB from the value shown on the typical curve.
⎠
R1
R
P
PARASITIC
LINE RESISTANCE
V
IN
LT1083 OUT
ADJ
IN
Output Voltage
The LT1083 develops a 1.25V reference voltage between
the output and the adjust terminal (see Figure 1). By
placing a resistor R1 between these two terminals, a
constant current is caused to flow through R1 and down
through R2 to set the overall output voltage. Normally this
current is the specified minimum load current of 10mA.
R1*
R2*
R
L
*CONNECT R1 TO CASE
CONNECT R2 TO LOAD
1083/4/5 ADJ F02
Because I
is very small and constant when compared
ADJ
with the current through R1, it represents a small error
and can usually be ignored.
Figure 2. Connections for Best Load Regulation
108345fg
11
LT1083/LT1084/LT1085
APPLICATIONS INFORMATION
Connected as shown, R is not multiplied by the divider
compound at the case-to-heat sink interface is strongly
recommended. If the case of the device must be electri-
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 electrically connected to the output.
P
ratio. R is about 0.004Ω per foot using 16-gauge wire.
P
This translates to 4mV/ft at 1A load current, so it is im-
portant to keep the positive lead between regulator and
load as short as possible and use large wire or PC board
traces.
For example, using an LT1083CK (TO-3, Commercial)
and assuming:
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
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 Transistor. Previous regulators, with a
single junction-to-case thermal resistance specification,
usedanaverageofthetwovaluesprovidedhereandthere-
fore 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.
V (Max Continuous) = 9V, V
= 5V, I
= 6A,
OUT
IN
OUT
T = 75°C, θ
= 1°C/W,
A
HEAT SINK
θ
= 0.2°C/W for K package with
CASE-TO-HEAT SINK
thermal compound.
Power dissipation under these conditions is equal to:
P = (V – V )(I ) = 24W
D
IN
OUT OUT
Junction temperature will be equal to:
T = T + P (θ + θ
+ θ )
J
A
D
HEAT SINK
CASE-TO-HEAT SINK
JC
For the Control Section:
T = 75°C + 24W (1°C/W + 0.2°C/W + 0.6°C/W) = 118°C
J
118°C < 125°C = T
Commercial Range)
(Control Section
JMAX
For the Power Transistor:
T = 75°C + 24W (1°C/W + 0.2°C/W + 1.6°C/W) = 142°C
J
142°C < 150°C = T
Commercial Range)
(Power Transistor
JMAX
In both cases the junction temperature is below the maxi-
mum rating for the respective sections, ensuring reliable
operation.
Junction-to-case thermal resistance is specified from the
IC junction to the bottom of the case directly below the
die. This is the lowest resistance path for heat flow. Proper
mounting is required to ensure the best possible thermal
flowfromthisareaofthepackagetotheheatsink.Thermal
108345fg
12
LT1083/LT1084/LT1085
TYPICAL APPLICATION
7.5A Variable Regulator
T1
L
1mH
TRIAD
C30B
F-269U
0V TO 35V
IN
LT1083 OUT
OA TO 7.5A
+
ADJ
20Ω
20Ω
T2
750Ω* 1.5k
100μF
3
+
C1
50,000μF
110VAC
1N4003
LT1004-1.2
1N914
2
1
C30B
1N4003
2k
1N4003
OUTPUT
ADJUST
16k*
11k*
1μF
560Ω
15k
15V
LT1004-1.2
2.7k
82k
10k
16k*
–15V
4
8
200k
2
+
–
7
–15V
LT1011
3
0.1μF
1
1N4148
NC
100pF
15V
2N3904
8
–15V
4
3
1
–
+
7
3
2
8
LT1011
+
10k
6
2
LM301A
1% FILM RESISTOR
L: DALE TO-5 TYPE
*
1
–
7
15V
15K
15V
T2: STANCOR 11Z-2003
4
–15V
11k*
GENERAL PURPOSE REGULATOR WITH SCR PREREGULATOR
TO LOWER POWER DISSIPATION. ABOUT 1.7V DIFFERENTIAL
IS MAINTAINED ACROSS THE LT1083 INDEPENDENT OF OUTPUT
VOLTAGE AND LOAD CURRENT
LT1083/4/5 ADJ TA05
1μF
108345fg
13
LT1083/LT1084/LT1085
TYPICAL APPLICATION
Paralleling Regulators
2 FEET #18 WIRE*
V
IN
IN
LT1083 OUT
IN
ADJ
R2
R1
V
= 1.25V 1 +
(
OUT
)
I
= 0A TO 15A
OUT
0.015Ω
LT1083 OUT
ADJ
*THE #18 WIRE ACTS
AS BALLAST RESISTANCE
INSURING CURRENT SHARING
BETWEEN BOTH DEVICES
R1
120Ω
LT1083/4/5 ADJ TA03
R2
Improving Ripple Rejection
V
OUT
LT1083
ADJ
OUT
V
IN
IN
5V
R1
121Ω
1%
+
+
10μF
150μF
R2
365Ω
1%
+
C1
25μF*
*C1 IMPROVES RIPPLE REJECTION.
SHOULD BE < R1 AT RIPPLE FREQUENCY
X
C
1083/4/5 ADJ TA04
Remote Sensing
R
P
(MAX DROP 300mV)
V
OUT
V
IN
LT1083 OUT
ADJ
IN
5V
+
V
IN
100μF
2
3
7
–
25Ω
6
LM301A
1k
+
1
+
121Ω
R
L
10μF
8
4
5μF
100pF
365Ω
+
RETURN
25Ω
RETURN
1083/4/5 ADJ TA07
108345fg
14
LT1083/LT1084/LT1085
TYPICAL APPLICATION
High Efficiency Regulator with Switching Preregulator
1mH
V
IN
IN
LT1083 OUT
ADJ
V
OUT
28V
+
MR1122
10,000μF
28V
240Ω
2k
470Ω
1N914
10k
1k
1M
4N28
10k
+
1083/4/5 ADJ TA06
LT1011
10k
28V
–
1N914
1.2V to 15V Adjustable Regulator
†
V
IN
LT1083 OUT
ADJ
V
OUT
IN
R1
90.9Ω
+
+
C1*
10μF
C2
100μF
R2
1k
*NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS
†
R2
R1
V
OUT
= 1.25V 1 +
1083/4/5 ADJ TA08
5V Regulator with Shutdown*
V
OUT
LT1083
ADJ
V
OUT
IN
IN
5V
121Ω
1%
+
10μF
1k
+
100μF
365Ω
1%
2N3904
TTL
1k
1083/4/5 ADJ TA09
*OUTPUT SHUTS DOWN TO 1.3V
108345fg
15
LT1083/LT1084/LT1085
PACKAGE DESCRIPTION
K Package
2-Lead TO-3 Metal Can
(Reference LTC DWG # 05-08-1310)
1.177 – 1.197
(29.90 – 30.40)
.760 – .775
.655 – .675
(16.64 – 17.15)
.320 – .350
(8.13 – 8.89)
(19.30 – 19.69)
.060 – .135
.210 – .220
(1.524 – 3.429)
(5.33 – 5.59)
.151 – .161
(3.86 – 4.09)
DIA, 2PLCS
.420 – .480
.167 – .177
(10.67 – 12.19)
(4.24 – 4.49)
R
.425 – .435
(10.80 – 11.05)
.038 – .043
(0.965 – 1.09)
.067 – .077
(1.70 – 1.96)
.490 – .510
(12.45 – 12.95)
R
K2 (TO-3) 080
OBSOLETE PACKAGE
M Package
3-Lead Plastic DD Pak
(Reference LTC DWG # 05-08-1460)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
.060
(1.524)
.165 – .180
(4.191 – 4.572)
.256
(6.502)
.045 – .055
(1.143 – 1.397)
15°
+.008
.004
–.004
.060
(1.524)
.183
(4.648)
.330 – .370
(8.382 – 9.398)
.059
(1.499)
+0.203
–0.102
0.102
(
)
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.100
(2.54)
BSC
.050 .012
(1.270 0.305)
.300
(7.620)
+.012
.143
.013 – .023
(0.330 – 0.584)
–.020
.050
(1.270)
+0.305
3.632
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
(
)
–0.508
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
RECOMMENDED SOLDER PAD LAYOUT
.420
.420
.080
.276
.350
.325
.205
.320
.565
.565
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.090
.090
M (DD3) 0204
.100
.070
.070
.100
108345fg
16
LT1083/LT1084/LT1085
PACKAGE DESCRIPTION
P Package
3-Lead Plastic TO-3P (Similar to TO-247)
(Reference LTC DWG # 05-08-1450)
.560
.187 – .207
(4.75 – 5.26)
(14.224)
.620 – .64O
(15.75 – 16.26)
.325
(8.255)
.275
(6.985)
.060 – .080
(1.52 – 2.03)
MOUNTING HOLE
18° – 22°
.115 – .145
(2.92 – 3.68)
DIA
.580
(14.732)
.830 – .870
.170 – .2OO
(21.08 – 22.10)
(4.32 – 5.08)
.700
(17.780)
EJECTOR PIN MARKS
.105 – .125
.580 – .6OO
(14.73 – 15.24)
(2.67 – 3.18)
DIA
.098
(2.489)
3° – 7°
.170
(4.32)
MAX
.124
(3.149)
.780 – .800
(19.81 – 20.32)
.042 – .052
(1.07 – 1.32)
.215
(5.46)
BSC
.087 – .102
(2.21 – 2.59)
BOTTOM VIEW OF TO-3P
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
.020 – .040
(0.51 – 1.02)
P3 0801
.074 – .084
(1.88 – 2.13)
.113 – .123
(2.87 – 3.12)
T Package
3-Lead Plastic TO-220
(Reference LTC DWG # 05-08-1420)
.147 – .155
(3.734 – 3.937)
DIA
.165 – .180
(4.191 – 4.572)
.390 – .415
(9.906 – 10.541)
.045 – .055
(1.143 – 1.397)
.230 – .270
(5.842 – 6.858)
.570 – .620
(14.478 – 15.748)
.460 – .500
(11.684 – 12.700)
.330 – .370
(8.382 – 9.398)
.980 – 1.070
(24.892 – 27.178)
.520 – .570
(13.208 – 14.478)
.218 – .252
(5.537 – 6.401)
.013 – .023
(0.330 – 0.584)
.100
(2.540)
BSC
.095 – .115
(2.413 – 2.921)
T3 (TO-220) 0801
.050
(1.270)
TYP
.028 – .038
(0.711 – 0.965)
108345fg
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
17
LT1083/LT1084/LT1085
TYPICAL APPLICATIONS
Automatic Light Control
LT1083
ADJ
V
OUT
IN
IN
1.2k
+
100μF
10μF
1083/4/5 ADJ TA10
Protected High Current Lamp Driver
12V
5A
LT1083
ADJ
15V
IN
OUT
TTL OR
CMOS
1083/4/5 ADJ TA11
10k
RELATED PARTS
PART NUMBER
LT1086
DESCRIPTION
COMMENTS
1.5A Low Dropout Regulator
800mA Low Dropout Regulator
Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output
Fixed 2.85V, 3.3V, 5V or Adjustable Output
For High Performance Microprocessors
LT1117
LT1584/LT1585/LT1587
LT1580
7A/4.6A/3A Fast Response Low Dropout Regulators
7A Very Low Dropout Linear Regulator
0.54V Dropout at 7A, Fixed 2.5V
and Adjustable
OUT
LT1581
10A Very Low Dropout Linear Regulator
High Power Step-Down Switching Regulator
0.43V Dropout at 10A, Fixed 2.5V
and Adjustable
OUT
LT1430
5V to 3.3V at 10A, >90% Efficiency
External MOSFET Pass Element
External PNP Pass Element
™
LT1575
UltraFast Transient Response LDO Controller
LT1573
UltraFast Transient Response LDO Controller
UltraFast is a trademark of Linear Technology Corporation.
108345fg
LT 0409 REV G • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
18
●
●
© LINEAR TECHNOLOGY CORPORATION 1994
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号：
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SEMTECH
LT1085CM#PBF
LT1085 - 7.5A, 5A, 3A Low Dropout Positive Adjustable Regulators; Package: DD PAK; Pins: 3; Temperature Range: 0°C to 70°C
Linear
LT1085CM#TRPBF
LT1085 - 7.5A, 5A, 3A Low Dropout Positive Adjustable Regulators; Package: DD PAK; Pins: 3; Temperature Range: 0°C to 70°C
Linear
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