LT1083/LT1084/LT1085
7.5A, 5A, 3A Low Dropout
Positive Adjustable Regulators
FEATURES
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DESCRIPTIO
Three-Terminal Adjustable
Output Current of 3A, 5A or 7.5A
Operates Down to 1V Dropout
Guaranteed Dropout Voltage at Multiple Current Levels
Line Regulation: 0.015%
Load Regulation: 0.1%
100% Thermal Limit Functional Test
Fixed Versions Available
Available in 3-Lead Plastic TO-220, TO-3P and DD
Packages
APPLICATIO S
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The LT
®
1083 series of positive adjustable regulators are
designed to provide 7.5A, 5A and 3A with higher efficiency
than currently available devices. All internal circuitry is
designed to operate down to 1V input-to-output differen-
tial 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 reference voltage
to 1%. Current limit is also trimmed, minimizing the stress
on both the regulator and power source circuitry under
overload conditions.
The LT1083/LT1084/LT1085 devices are pin compatible
with older three-terminal regulators. A 10µF output ca-
pacitor is required on these new devices. However, this is
included in most regulator designs.
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
High Efficiency Linear Regulators
Post Regulators for Switching Supplies
Constant Current Regulators
Battery Chargers
DEVICE
LT1083
LT1084
LT1085
OUTPUT CURRENT*
7.5A
5.0A
3.0A
*For a 1.5A low dropout regulator see the LT1086 data sheet.
TYPICAL APPLICATIO
5V, 7.5A Regulator
INPUT/OUTPUT VOLTAGE DIFFERENTIAL (V)
2
Dropout Voltage vs Output Current
V
IN
≥
6.5V
IN
LT1083
ADJ
OUT
121Ω
1%
5V AT 7.5A
+
10µF
+
10µF*
TANTALUM
1
365Ω
1%
*REQUIRED FOR STABILITY
1083/4/5 ADJ TA01
0
0
OUTPUT CURRENT
U
I
FULL LOAD
1083/4/5 ADJ TA02
U
U
108345fe
1
LT1083/LT1084/LT1085
ABSOLUTE
MAXIMUM
RATINGS
PRECO DITIO I G
100% thermal shutdown functional test.
PACKAGE/ORDER INFORMATION
FRONT VIEW
TAB
IS
OUTPUT
3
2
1
T PACKAGE
3-LEAD PLASTIC TO-220
θ
JA
= 50°C/W
V
IN
V
OUT
ADJ
ORDER PART
NUMBER
LT1084CT
LT1084IT
LT1085CT
LT1085IT
TAB IS
OUTPUT
FRONT VIEW
3
2
1
P PACKAGE
3-LEAD PLASTIC TO-3P
θ
JA
= 35°C/W
BOTTOM VIEW
V
IN
2
CASE IS
OUTPUT
1
ADJ
K PACKAGE
2-LEAD TO-3 METAL CAN
θ
JA
= 35°C/W
LT1083CK
LT1083MK
LT1084CK
LT1084MK
LT1085CK
LT1085MK
FRONT VIEW
3
TAB
IS
OUTPUT
2
1
M PACKAGE
3-LEAD PLASTIC DD
θ
JA
= 30°C/W*
*WITH PACKAGE SOLDERED TO 0.5IN
2
COPPER AREA
OVER BACKSIDE GROUND PLANE OR INTERNAL POWER
PLANE.
θ
JA
CAN VARY FROM 20°C/W TO > 40°C/W
DEPENDING ON MOUNTING TECHNIQUE.
OBSOLETE PACKAGE
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
PARAMETER
Reference Voltage
CONDITIONS
I
OUT
= 10mA, T
J
= 25°C,
(V
IN
– V
OUT
) = 3V
10mA
≤
I
OUT
≤
I
FULL LOAD
1.5V
≤
(V
IN
– V
OUT
)
≤
25V (Notes 4, 6, 7)
I
LOAD
= 10mA, 1.5V
≤
(V
IN
– V
OUT
)
≤
15V, T
J
= 25°C (Notes 2, 3)
M Grade: 15V
≤
(V
IN
– V
OUT
)
≤
35V (Notes 2, 3)
C, I Grades: 15V
≤
(V
IN
– V
OUT
)
≤
30V (Notes 2, 3)
MIN
1.238
●
●
●
●
ELECTRICAL CHARACTERISTICS
Line Regulation
2
UU
U
Power Dissipation ............................... Internally Limited
Input-to-Output Voltage Differential
“C” Grades .......................................................... 30V
“I” Grades ............................................................ 30V
“M” Grades
(OBSOLETE)............................
35V
Operating Junction Temperature Range
“C” Grades: Control Section .................. 0°C to 125°C
Power Transistor ............... 0°C to 150°C
“I” Grades: Control Section ............. – 40°C to 125°C
Power Transistor .......... – 40°C to 150°C
U
U
W
W W
U
W
(Note 1)
“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
ORDER PART
NUMBER
V
IN
V
OUT
ADJ
LT1083CP
LT1084CP
V
IN
V
OUT
ADJ
LT1085CM
TYP
1.250
1.250
0.015
0.035
0.05
0.05
MAX
1.262
1.270
0.2
0.2
0.5
0.5
UNITS
V
V
%
%
%
%
108345fe
1.225
LT1083/LT1084/LT1085
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
PARAMETER
Load Regulation
CONDITIONS
(V
IN
– V
OUT
) = 3V
10mA
≤
I
OUT
≤
I
FULL LOAD
T
J
= 25°C (Notes 2, 3, 4, 6)
●
ELECTRICAL CHARACTERISTICS
MIN
TYP
MAX
UNITS
Dropout Voltage
Current Limit
LT1083
LT1084
LT1085
Minimum Load Current
Thermal Regulation
LT1083
LT1084
LT1085
Ripple Rejection
Adjust Pin Current
Adjust Pin Current Change
Temperature Stability
Long Term Stability
RMS Output Noise (% of V
OUT
)
Thermal Resistance Junction-to-Case
LT1083
LT1084
∆V
REF
= 1%, I
OUT
= I
FULLLOAD
(Notes 5, 6, 8)
(V
IN
– V
OUT
) = 5V
(V
IN
– V
OUT
) = 25V
(V
IN
– V
OUT
) = 5V
(V
IN
– V
OUT
) = 25V
(V
IN
– V
OUT
) = 5V
(V
IN
– V
OUT
) = 25V
(V
IN
– V
OUT
) = 25V
T
A
= 25°C, 30ms Pulse
●
●
●
●
●
●
●
●
0.1
0.2
1.3
8.0
0.4
5.5
0.3
3.2
0.2
9.5
1.0
6.5
0.6
4.0
0.5
5
0.002
0.003
0.004
0.3
0.4
1.5
%
%
V
A
A
A
A
A
A
mA
%/W
%/W
%/W
dB
µA
µA
µA
%
%
%
10
0.010
0.015
0.020
f = 120Hz, C
ADJ
= 25µF, C
OUT
= 25µF Tantalum
I
OUT
= I
FULL LOAD
, (V
IN
– V
OUT
) = 3V (Notes 6, 7, 8)
T
J
= 25°C
10mA
≤
I
OUT
≤
I
FULL LOAD
1.5V
≤
(V
IN
– V
OUT
)
≤
25V (Note 6)
T
A
= 125°C, 1000 Hrs
T
A
= 25°C
10Hz =
≤
f
≤
10kHz
Control Circuitry/Power Transistor
K Package
P Package
K Package
P Package
T Package
K Package
M, T Packages
●
●
●
●
60
75
55
120
0.2
0.5
0.3
0.003
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
5
1
LT1085
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
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.
Note 3:
Line and load regulation are guaranteed up to the maximum power
dissapation (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 4:
I
FULL LOAD
is defined in the current limit curves. The I
FULLLOAD
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.
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
FULL LOAD
is 5A for – 55°C
≤
T
J
< – 40°C and 7.5A for
T
J
≥
–40°C.
Note 7:
1.7V
≤
(V
IN
– V
OUT
)
≤
25V for LT1084 at – 55°C
≤
T
J
≤
– 40°C.
Note 8:
Dropout is 1.7V maximum for LT1084 at – 55°C
≤
T
J
≤
– 40°C.
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LT1083/LT1084/LT1085
TYPICAL PERFORMANCE CHARACTERISTICS
LT1083
Dropout Voltage
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
2
INDICATES GUARANTEED TEST POINT
SHORT-CIRCUIT CURRENT (A)
10
8
6
4
2
0
–55°C
25°C
150°C
OUTPUT VOLTAGE DEVIATION (%)
–40°C
≤
T
J
≤
150°C
0°C
≤
T
J
≤
125°C
1
T
J
= 150°C
T
J
= 25°C
T
J
= –55°C
0
0
1
2
3 4 5 6 7 8
OUTPUT CURRENT (A)
LT1084
Dropout Voltage
MINIMUN INPUT/OUTPUT DIFFERENTIAL (V)
2
INDICATES GUARANTEED TEST POINT
SHORT-CIRCUIT CURRENT (A)
–55°C
≤
T
J
≤
150°C
0°C
≤
T
J
≤
125°C
OUTPUT VOLTAGE DEVIATION (%)
1
T
J
= –55°C
T
J
= 150°C
T
J
= 25°C
0
0
1
3
4
2
OUTPUT CURRENT (A)
5
6
LT1083/4/5 ADJ G04
LT1085
Dropout Voltage
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
2
INDICATES GUARANTEED TEST POINT
–55°C
≤
T
J
≤
150°C
0°C
≤
T
J
≤
125°C
SHORT-CIRCUIT CURRENT (A)
5
4
3
–55°C
2
1
0
I
FULL LOAD
GUARANTEED
25°C
150°C
OUTPUT VOLTAGE DEVIATION (%)
1
T
J
= 25°C
T
J
= 150°C
T
J
= –55°C
0
0
3
2
1
OUTPUT CURRENT (A)
4
LT1083/4/5 ADJ G07
4
U W
9
LT1083/4/5 ADJ G01
LT1083
Short-Circut Current
12
LT1083
Load Regulation
0.10
∆I
= 7.5A
0.05
0
–0.05
–0.10
–0.15
–0.20
–50 –25
I
FULL LOAD
GUARANTEED
0
20
30
15
25
5
10
INPUT/OUTPUT DIFFERENTIAL (V)
35
10
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 ADJ G03
LT1083/4/5 ADJ G02
10
9
8
7
6
5
4
3
2
1
0
LT1084
Short-Circut Current
0.10
LT1084
Load Regulation
∆I
= 5A
0.05
0
–0.05
–0.10
–0.15
–0.20
–50 –25
150°C
25°C
–55°C
I
FULL LOAD
GUARANTEED
0
20
15
10
25
30
5
INPUT/OUTPUT DIFFERENTIAL (V)
35
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 ADJ G06
LT1083/4/5 ADJ G05
LT1085
Short-Circut Current
6
LT1085
Load Regulation
0.10
∆I
= 3A
0.05
0
–0.05
–0.10
–0.15
–0.20
–50 –25
0
20
30
15
25
5
10
INPUT/OUTPUT DIFFERENTIAL (V)
35
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 ADJ G09
LT1083/4/5 ADJ G08
108345fe
LT1083/LT1084/LT1085
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum Operating Current
10
MINIMUM OPERATING CURRENT (mA)
9
1.26
ADJUST PIN CURRENT (µA)
REFERENCE VOLTAGE (V)
8
7
6
5
4
3
2
1
0
0
20
15
10
25
30
5
INPUT/OUTPUT DIFFERENTIAL (V)
35
T
J
= –55°C
T
J
= 25°C
T
J
= 150°C
LT1083/4/5 ADJ G10
LT1083
Ripple Rejection
100
90
80
RIPPLE REJECTION (dB)
70
60
50
40
30
20
10
0
10
100
1k
10k
FREQUENCY (Hz)
100k
C
ADJ
= 200µF AT FREQUENCIES < 60Hz
C
ADJ
= 25µF AT FREQUENCIES > 60Hz
I
OUT
= 7A
V
RIPPLE
≤
3V
P-P
V
RIPPLE
≤
0.5V
P-P
RIPPLE REJECTION (dB)
(V
IN
– V
OUT
)
≥
3V
POWER (W)
(V
IN
– V
OUT
)
≥
V
DROPOUT
LT1084
Ripple Rejection
100
90
80
RIPPLE REJECTION (dB)
70
60
50
40
30
20
10
0
10
100
1k
10k
FREQUENCY (Hz)
100k
C
ADJ
= 200µF AT FREQUENCIES < 60Hz
C
ADJ
= 25µF AT FREQUENCIES > 60Hz
I
OUT
= 5A
V
RIPPLE
≤
3V
P-P
V
RIPPLE
≤
0.5V
P-P
RIPPLE REJECTION (dB)
(V
IN
– V
OUT
)
≥
3V
(V
IN
– V
OUT
)
≥
V
DROPOUT
60
50
40
30
20
10
0
0
POWER (W)
U W
1083/4/5 ADJ G13
1083/4/5 ADJ G16
Temperature Stability
1.27
100
90
80
70
60
50
40
30
20
10
1.23
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 ADJ G11
Adjust Pin Current
1.25
1.24
0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 ADJ G12
LT1083
Ripple Rejection vs Current
100
90
80
70
60
50
40
30
20
10
0
0
1
6
4
3
2
5
OUTPUT CURRENT (A)
7
8
V
OUT
= 5V
C
ADJ
= 25µF
C
OUT
= 25µF
f
R
= 20kHz
V
RIPPLE
≤
0.5V
P-P
f
R
= 120Hz
V
RIPPLE
≤
3V
P-P
100
90
80
70
60
50
40
30
20
10
0
LT1083
Maximum Power Dissipation*
LT1083MK
LT1083CP
LT1083CK
1083/4/5 ADJ G14
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1083/4/5 ADJ G15
LT1084
Ripple Rejection vs Current
100
90
80
70
f
R
= 20kHz
V
RIPPLE
≤
0.5V
P-P
f
R
= 120Hz
V
RIPPLE
≤
3V
P-P
60
50
LT1084
Maximum Power Dissipation*
LT1084MK
40
30
LT1084CT
20
LT1084CP
V
OUT
= 5V
C
ADJ
= 25µF
C
OUT
= 25µF
1
4
3
2
OUTPUT CURRENT (A)
5
10
0
LT1084CK
1083/4/5 ADJ G17
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1083/4/5 ADJ G18
108345fe
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