LT1083/LT1084/LT1085 Fixed
1
1083ffe
For more information www.linear.com/LT1083
Typical applicaTion
DescripTion
3A, 5A, 7.5A Low Dropout
Positive Fixed Regulators
The LT
®
1083 series of positive adjustable regulators are
designed to provide 3A, 5A and 7.5A with higher efficiency
than currently available devices. All internal circuitry is
designed to operate down to 1V input to output differential
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.
The LT1083 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.
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.
FeaTures
applicaTions
n Three-Terminal 3.3V, 3.6V, 5V and 12V
n Output Current of 3A, 5A or 7.5A
n Operates Down to 1V Dropout
n Guaranteed Dropout Voltage at Multiple Current Levels
n Line Regulation: 0.015%
n Load Regulation: 0.1%
n 100% Thermal Limit Functional Test
n Adjustable Versions Available
n High Efficiency Linear Regulators
n Post Regulators for Switching Supplies
n Constant Current Regulators
n Battery Chargers
DEVICE OUTPUT CURRENT*
LT1083
LT1084
LT1085
7.5 Amps
5.0 Amps
3.0 Amps
*For a 1.5A low dropout regulator see the LT1086 data sheet.
5V, 7.5A Regulator
VIN ≥ 6.5V 5V AT 7.5A
LT1083-5
LT1083/4/5 TA01
22µF*
TANTALUM
+
10µF
+
*REQUIRED FOR STABILITY
Dropout Voltage vs Output Current
OUTPUT CURRENT (A)
0
INPUT/OUTPUT VOLTAGE DIFFERENTIAL (V)
2
1
0
1083/4/5 TA02
I
FULLLOAD
/2 I
FULLLOAD
L, LT , LT C , LT M , Linear Technology, the Linear logo and OPTI-LOOP are registered trademarks
and UltraFast is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
LT1083/LT1084/LT1085 Fixed
2
1083ffe
For more information www.linear.com/LT1083
absoluTe MaxiMuM raTings
orDer inForMaTion
Power Dissipation .............................. Internally Limited
Input Voltage* .......................................................... 30V
Operating Input Voltage
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
I-Grades: Control Section .............. –40°C to 125°C
Power Transistor ............ –40°C to 150°C
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
100% Thermal Limit Functional Test.
*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.
(Note 1)
preconDiTioning
TAB IS
OUTPUT
T PACKAGE
3-LEAD PLASTIC TO-220
VIN
VOUT
GND
FRONT VIEW
3
2
1
θJA = 50°C/W
VIN
VOUT
GND
P PACKAGE
3-LEAD TO-3P PLASTIC
FRONT VIEW
TAB IS
OUTPUT
3
2
1
θJA = 35°C/W
OBSOLETE PACKAGE
1
2
VIN CASE IS
OUTPUT
GND
K PACKAGE
2-LEAD TO-3 METAL CAN
θJA = 35°C/W
OBSOLETE PACKAGE
TAB IS
OUTPUT
M PACKAGE
3-LEAD PLASTIC DD
FRONT VIEW
VIN
VOUT
GND
3
2
1
θJA = 30°C/W*
*WITH PACKAGE SOLDERED TO 0.5IN2 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
LT1083/LT1084/LT1085 Fixed
3
1083ffe
For more information www.linear.com/LT1083
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1083CP-5#PBF NA LT1083CP-5 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1083CP-12#PBF NA LT1083CP-12 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CP-5#PBF NA LT1084CP-5 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CP-12#PBF NA LT1084CP-12 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
OBSOLETE PACKAGE
LT1084CT-3.3#PBF NA LT1084CT- 3.3 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CT-5#PBF NA LT1084C T-5 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CT-12#PBF NA LT1084C T-12 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-3.3#PBF NA LT1085C T-3.3 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-3.6#PBF NA LT1085C T-3.6 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-5#PBF NA LT1085C T-5 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-12#PBF NA LT1085-12 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CM-3.3#PBF LT1085CM-3.3#TRPBF LT1085CM-3.3 3-Lead Plastic DD Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CM-3.6#PBF LT1085CM-3.6#TRPBF LT1085CM-3.6 3-Lead Plastic DD Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085IM-3.6#PBF LT1085IM-3.6#TRPBF LT1085IM-3.6 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-5 NA LT1083CP-5 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1083CP-12 NA LT1083CP-12 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CP-5 NA LT1084CP-5 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CP-12 NA LT1084CP-12 3-Lead Plastic TO-3P Control: 0°C to 125°C
Power: 0°C to 150°C
LT1083CK-5 NA LT1083CK-5 2-Lead TO-3 Metal Can Control: 0°C to 125°C
Power: 0°C to 150°C
LT1083CK-12 NA LT1083CK-12 2-Lead TO-3 Metal Can Control: 0°C to 125°C
Power: 0°C to 150°C
LT1083MK-5 NA LT1083MK-5 2-Lead TO-3 Metal Can Control: –55°C to 150°C
Power: –55°C to 200°C
LT1083MK-12 NA LT1083MK-12 2-Lead TO-3 Metal Can Control: –55°C to 150°C
Power: –55°C to 200°C
LT1083/LT1084/LT1085 Fixed
4
1083ffe
For more information www.linear.com/LT1083
orDer inForMaTion
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1084CK-5 NA LT1084CK-5 2-Lead TO-3 Metal Can Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CK-12 NA LT1084CK-12 2-Lead TO-3 Metal Can Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084MK-5 NA LT1084MK-5 2-Lead TO-3 Metal Can Control: –55°C to 150°C
Power: –55°C to 200°C
LT1084MK-12 NA LT1084MK-12 2-Lead TO-3 Metal Can Control: –55°C to 150°C
Power: –55°C to 200°C
LT1085CK-5 NA LT1085CK-5 2-Lead TO-3 Metal Can Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CK-12 NA LT1085CK-12 2-Lead TO-3 Metal Can Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085MK-5 NA LT1085MK-5 2-Lead TO-3 Metal Can Control: –55°C to 150°C
Power: –55°C to 200°C
LT1085MK-12 NA LT1085MK-12 2-Lead TO-3 Metal Can Control: –55°C to 150°C
Power: –55°C to 200°C
OBSOLETE PACKAGE
LT1084CT-3.3 NA LT1084C T-3.3 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CT-5 NA LT1084C T-5 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1084CT-12 NA LT1084C T-12 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-3.3 NA LT1085C T-3.3 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-3.6 NA LT1085C T-3.6 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-5 NA LT1085C T-5 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CT-12 NA LT1085-12 3-Lead Plastic TO-220 Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CM-3.3 LT1085CM-3.3#TR LT1085CM-3.3 3-Lead Plastic DD Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085CM-3.6 LT1085CM-3.6#TR LT1085CM-3.6 3-Lead Plastic DD Control: 0°C to 125°C
Power: 0°C to 150°C
LT1085IM-3.6 LT1085IM-3.6#TR LT1085IM-3.6 3-Lead Plastic DD Control: –40°C to 125°C
Power: –40°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
LT1083/LT1084/LT1085 Fixed
5
1083ffe
For more information www.linear.com/LT1083
elecTrical characTerisTics
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage LT1084-3.3 IOUT = 0mA, TJ = 25°C, VIN = 8V (K Package Only)
4.8V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULL_LOAD (Notes 3, 4, 9)
l
3.270
3.235
3.300
3.300
3.330
3.365
V
V
LT1085-3.3 VIN = 5V, IOUT = 0mA, TJ = 25°C (K Package Only)
4.8V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULL_LOAD (Notes 3, 4, 9)
l
3.270
3.235
3.300
3.300
3.330
3.365
V
V
LT1085-3.6 VIN = 5V, IOUT = 0mA, TJ = 25°C (K Package Only)
5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULL_LOAD (Note 9)
5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULL_LOAD, TJ ≥ 0°C (Notes 3, 4, 9)
l
3.564
3.500
3.528
3.600 3.636
3.672
3.672
V
V
V
LT1085-3.6 5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ 2.5A (Notes 3, 4, 9)
VIN = 4.75V, IOUT = 3A, TJ ≥ 0°C
VIN = 4.75V, IOUT = 2.5A, TJ ≥ 0°C
VIN = 4.75V, IOUT = 1.5A, TJ > 0°C
l3.528
3.350
3.450
3.528
3.672
3.672
3.672
3.672
V
V
V
V
LT1083/4/5-5 IOUT = 0mA, TJ = 25°C, VIN = 8V (K Package Only)
0 ≤ IOUT ≤ IFULL_LOAD, 6.5V ≤ VIN ≤ 20V (Notes 4, 6, 7, 9)
4.950
4.900
5.000
5.000
5.050
5.100
V
V
LT1083/4/5-12 IOUT = 0mA, TJ = 25°C, VIN = 15V (K Package Only)
0 ≤ IOUT ≤ IFULL_LOAD, 13.5V ≤ VIN ≤ 25V (Notes 4, 6, 7, 9)
11.880
11.760
12.000
12.000
12.120
12.240
V
V
Line Regulation LT1084-3.3 IOUT = 0mA, TJ = 25°C, 4.8V ≤ VIN ≤ 15V
l
0.5
1.0
6
6
mV
mV
LT1085-3.3 4.8V ≤ VIN ≤ 15V, IOUT = 0mA, TJ= 25°C
l
0.5
1.0
6
6
mV
mV
LT1085-3.6 4.8V ≤ VIN ≤ 15V, IOUT = 0mA, TJ= 25°C
l
0.5
1.0
6
6
mV
mV
LT1083/4/5-5 IOUT = 0mA, TJ = 25°C, 6.5V ≤ VIN ≤ 20V (Notes 2, 3)
l
0.5
1.0
10
10
mV
mV
LT1083/4/5-12 IOUT = 0mA, TJ = 25°C, 13.5V ≤ VIN ≤ 25V (Notes 2, 3)
l
1.0
2.0
25
25
mV
mV
Load Regulation LT1084-3.3 VIN = 5V, 0 ≤ IOUT ≤ 5A, TJ = 25°C
l
3
7
15
20
mV
mV
LT1085-3.3 VIN = 5V, 0 ≤ IOUT ≤ 3A, TJ = 25°C
l
3
7
15
20
mV
mV
LT1085-3.6 VIN = 5.25V, 0 ≤ IOUT ≤ 3A, TJ = 25°C
l
3
7
15
20
mV
mV
LT1083/4/5-5 VIN = 8V, 0 ≤ IOUT ≤ IFULL_LOAD, TJ = 25°C (Notes 2, 3, 4, 6)
l
5
10
20
35
mV
mV
LT1083/4/5-12 VIN = 15V, 0 ≤ IOUT ≤ IFULL_LOAD, TJ = 25°C (Notes 2, 3, 4, 6)
l
12
24
36
72
mV
mV
Dropout Voltage LT1084/5-3.3 ∆VOUT = 33mV, IOUT = IFULL_LOAD (Notes 5, 6) l1.3 1.5 V
LT1085-3.6 ∆VOUT = 36mV, IOUT = IFULL_LOAD (Notes 5, 6) l1.3 1.5 V
LT1083/4/5-5 ∆VOUT = 50mV, IOUT = IFULL_LOAD (Notes 5, 6) l1.3 1.5 V
LT1083/4/5-12 ∆VOUT = 120mV, IOUT = IFULL_LOAD (Notes 5, 6) l1.3 1.5 V
Current Limit LT1083-5 VIN = 10V l8.0 9.5 A
LT1083-12 VIN = 17V l8.0 9.5 A
LT1084-3.3 VIN = 8V l5.5 6.5 A
LT1084-5 VIN = 10V l5.5 6.5 A
LT1084-12 VIN = 17V l5.5 6.5 A
LT1085-3.3/3.6 VIN = 8V l3.2 4.0 A
LT1085-5 VIN = 10V l3.2 4.0 A
LT1085-12 VIN = 17V l3.2 4.0 A
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
LT1083/LT1084/LT1085 Fixed
6
1083ffe
For more information www.linear.com/LT1083
PARAMETER CONDITIONS MIN TYP MAX UNITS
Quiescent Current LT1084-3.3 VIN = 18V l5.0 10.0 mA
LT1085-3.3 VIN = 18V l5.0 10.0 mA
LT1085-3.6 VIN = 18V l5.0 10.0 mA
LT1083/4/5-5 VIN ≤ 20V l5.0 10.0 mA
LT1083/4/5-12 VIN ≤ 25V l5.0 10.0 mA
Thermal Regulation LT1083-5/12 TA = 25°C, 30ms pulse
LT1084-3.3/5/12
LT1085-3.3/3.6/5/12
0.002
0.003
0.004
0.010
0.015
0.020
%/W
%/W
%/W
Ripple Rejection f = 120Hz, COUT = 25µF Tantalum, IOUT = IFULL_LOAD (Note 4)
LT1084-3.3 f = 120Hz, COUT = 25µF Tantalum, IOUT = 5A, VIN = 6.3V
LT1085-3.3 f = 120Hz, COUT = 25µF Tantalum, VIN = 6.3V, IOUT = 3A
LT1085-3.6 f = 120Hz, COUT = 25µF Tantalum, VIN = 6.6V, IOUT = 3A
LT1083/4/5-5 VIN = 8V (Note 6)
LT1083/4/5-12 VIN = 15V (Note 6)
l
l
l
l
l
60
60
60
60
54
72
72
72
68
60
dB
dB
dB
dB
dB
Temperature Stability l0.5 %
Long Term Stability TA = 125°C, 1000 Hrs. 0.03 1.0 %
RMS Output Noise
(% of VOUT)
TA = 25°C,
10Hz = ≤ f ≤ 10kHz
0.003
%
Thermal Resistance
Junction-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
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 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
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 4: IFULL_LOAD is defined in the current limit curves. The IFULL_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.
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 IFULL_LOAD is 5A for –55°C ≤ TJ ≤ – 40°C and 7.5A for
TJ ≥ – 40°C.
Note 7: 1.7V ≤ (VIN – VOUT) ≤ 25V for LT1084 at –55°C ≤ TJ ≤ – 40°C.
Note 8: Dropout voltage 1.7V maximum for LT1084 at
–55°C ≤ TJ ≤ –40°C.
Note 9: Full load current is not available at all input-output voltages.
See Notes 3, 4, 6.
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
LT1083/LT1084/LT1085 Fixed
7
1083ffe
For more information www.linear.com/LT1083
Typical perForMance characTerisTics
LT1084 Dropout Voltage LT1084 Short Circuit Current LT1084 Load Regulation
OUTPUT CURRENT (A)
0
0
MINIMUN INPUT/OUTPUT DIFFERENTIAL (V)
1
123 4
LT1083/4/5 FIXEDG04
5
2
6
INDICATES GUARANTEED TEST POINT
–55°C ≤ TJ ≤ 150°C
0°C ≤ TJ ≤ 125°C
TJ = 150°C
TJ = –55°C
TJ = 25°C
INPUT/OUTPUT DIFFERENTIAL (V)
0
0
SHORT-CIRCUIT CURRENT (A)
1
3
4
5
10
7
10 20 25
LT1083/4/5 FIXED G05
2
8
9
6
515 30 35
25°C
–55°C
150°C
GUARANTEED
I
FULL_LOAD
TEMPERATURE (°C)
–50
–0.20
–0.15
–0.10
–0.05
0.05
0.10
OUTPUT VOLTAGE DEVIATION (%)
0
0 50 100 150
LT1083/4/5 FIXED G06
–25 25 75 125
∆I = 5A
LT1085 Dropout Voltage
OUTPUT CURRENT (A)
0
0
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
1
2
12
LT1083/4/5 FIXED G07
34
INDICATES GUARANTEED TEST POINT
TJ = 150°C
TJ = 25°C
–55°C ≤ TJ ≤ 150°C
TJ = –55°C
0°C ≤ TJ ≤ 125°C
TEMPERATURE (°C)
–50
–0.20
–0.15
–0.10
–0.05
0.05
0.10
OUTPUT VOLTAGE DEVIATION (%)
0
0 50 100 150
LT1083/4/5 FIXED G09
–25 25 75 125
∆I = 3A
LT1085 Load Regulation
INPUT/OUTPUT DIFFERENTIAL (V)
0
SHORT-CIRCUIT CURRENT (A)
4
5
6
15 25
LT1083/4/5 FIXED G08
3
2
5 10 20 30 35
1
0
25°C
–55°C
I
FULL_LOAD
GUARANTEED
150°C
LT1085 Short-Circuit Current
OUTPUT CURRENT (A)
0
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
1
2
LT1083/4/5 FIXED G01
012345678910
INDICATES GUARANTEED TEST POINT
–40°C ≤ T
J
≤ 150°C
0°C ≤ T
J
≤ 125°C
T
J
= 150°C
T
J
= 25°C
T
J
= –55°C
TEMPERATURE (°C)
–50
–0.20
OUTPUT VOLTAGE DEVIATION (%)
–0.15
–0.10
–0.05
0
0 50 100 150
LT1083/4/5 FIXED G03
0.05
0.10
–25 25 75 125
∆I = 7.5A
LT1083 Dropout Voltage LT1083 Load RegulationLT1083 Short-Circuit Current
LT1083/LT1084/LT1085 Fixed
8
1083ffe
For more information www.linear.com/LT1083
Typical perForMance characTerisTics
30
40
50
20
10
0
60
70
80
FREQUENCY (Hz)
RIPPLE REJECTION (dB)
10 1k 10k 100k
1083/4/5 FIXED G13
100
V
RIPPLE
≤ 0.5V
P-P
V
RIPPLE
≤ 3V
P-P
(V
IN
– V
OUT
) ≥ 3V
(V
IN
– V
OUT
) ≥ V
DROPOUT
I
OUT
= I
FULL_LOAD
LT1083/4/5-12 Ripple Rejection
LT1085 Maximum Power
Dissipation*
CASE TEMPERATURE (°C)
50
POWER (W)
50
40
30
20
10
0
LT1083/4/5 FIXED G17
60 70 80 90 100 110 120 130 140 150
LT1085MK
LT1085CT
LT1085CK
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1084 Maximum Power
Dissipation*
CASE TEMPERATURE (°C)
50
POWER (W)
60
50
40
30
20
10
0
LT1083/4/5 FIXED G16
60 70 80 90 100 110 120 130 140 150
LT1084MK
LT1084CT LT1084CP
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1084CK
CASE TEMPERATURE (°C)
50
POWER (W)
100
90
80
70
60
50
40
30
20
10
0
LT1083/4/5 FIXED G15
60 70 80 90 100 110 120 130 140 150
LT1083MK
LT1083CP
LT1083CK
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1083 Maximum Power
Dissipation*
OUTPUT CURRENT (0 TO I
FULLLOAD
)
0
RIPPLE REJECTION (dB)
100
90
80
70
60
50
40
30
20
10
0
0.4 0.8 1.0
1083/4/5 FIXED G14
0.2 0.6
f
R
= 120Hz
V
RIPPLE
≤ 3V
P-P
f
R
= 20kHz
V
RIPPLE
≤ 0.5V
P-P
LT1083/4/5-12 Ripple Rejection
vs Current
LT1083/4/5-5 Ripple Rejection
vs Current
OUTPUT CURRENT (0 TO I
FULLLOAD
)
0
RIPPLE REJECTION (dB)
100
90
80
70
60
50
40
30
20
10
0
0.4 0.8 1.0
1083/4/5 FIXED G11
0.2 0.6
f
R
= 120Hz
V
RIPPLE
≤ 3V
P-P
f
R
= 20kHz
V
RIPPLE
≤ 0.5V
P-P
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE CHANGE (%)
0
1.0
150
LT1183/4/5 FIXED G12
–1.0
–2.0 050 100
2.0
–25 25 75 125
Temperature Stability
30
40
50
20
10
0
60
70
80
FREQUENCY (Hz)
RIPPLE REJECTION (dB)
10 1k 10k 100k
1083/4/5 FIXED G10
100
V
RIPPLE
≤ 0.5V
P-P
V
RIPPLE
≤ 3V
P-P
(V
IN
– V
OUT
) ≥ 3V
(V
IN
– V
OUT
) ≥ V
DROPOUT
I
OUT
= I
FULL_LOAD
LT1083/4/5-5 Ripple Rejection
LT1083/LT1084/LT1085 Fixed
9
1083ffe
For more information www.linear.com/LT1083
THERMAL
LIMIT
GND
V
OUT
LT1083/4/5 BD
V
IN
–
+
block DiagraM
applicaTions inForMaTion
The LT1083 family of three-terminal regulators are easy
to use and have all the protection features that are ex-
pected 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.
These regulators offer lower dropout voltage and more
precise reference tolerance. Further, the reference stability
with temperature is improved over older types of regula-
tors. The only circuit difference between using the LT1083
family and older regulators is that they require an output
capacitor for stability.
Stability
The circuit design used in the LT1083 family requires the
use of an output capacitor as part of the device frequency
compensation. For all operating conditions, the addition
of 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
characteristics are available. These capacitors differ in
capacitor tolerance (sometimes ranging up to ±100%),
equivalent series resistance, and capacitance temperature
coefficient. 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
response with heavy load current changes. Output capaci-
tance can be increased without limit and larger values of
output capacitance further improve stability and transient
response of the LT1083 regulators.
Another possible stability problem that can occur in mono-
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
LT1083/LT1084/LT1085 Fixed
10
1083ffe
For more information www.linear.com/LT1083
applicaTions inForMaTion
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 negative resistance is
a function of how fast the current limit is folded back as
input-to-
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
necessarily easy to solve; however it does not cause any
problems with the IC regulator and can usually be ignored.
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
values of surge current in normal operation. Only with
high value output capacitors, such as 1000µF to 5000µF
and with the input pin instantaneously shorted to ground,
can damage occur. A crowbar circuit at the input of the
LT1083 can generate those kinds of currents and a diode
from output-to-input is then recommended. Normal
power supply cycling or even plugging and unplugging
in the system will not generate currents large enough to
do any damage.
IN OUT
ADJ
V
OUT
LT1083
D1
1N4002
(OPTIONAL)
V
IN
1083/4/5 AI01
C
OUT
150µF
+
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.
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.
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.
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 by-
pass 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.
LT1083/LT1084/LT1085 Fixed
11
1083ffe
For more information www.linear.com/LT1083
applicaTions inForMaTion
Load Regulation
Because the LT1083 is a three-terminal device, it is not pos-
sible to provide true remote load sensing. Load regulation
will not be limited by the resistance of the wire connect-
ing 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.
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
ratings 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
new regulators provides a separate thermal resistance and
maximum junction temperature for both the Control Section
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.
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 flow from this area of the package to the heat sink.
Thermal compound at the case-to-heat sink interface is
strongly recommended. If the case of the device must
be electronically 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 output.
For example, using a LT1083-5CP (TO-3P, Commercial)
and assuming:
VIN(max continuous) = 9V, VOUT = 5V, IOUT = 6A,
TA = 75°C, θHEAT SINK = 1°C/W,
θ
CASE-TO-HEAT SINK = 0.2°C/W for P 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 + 0.5°C/W) =
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 maxi-
mum rating for the respective sections, ensuring reliable
operation.
LT1083/LT1084/LT1085 Fixed
12
1083ffe
For more information www.linear.com/LT1083
Typical applicaTions
7.5A Regulator
15V
15V
15V
110VAC
T1
TRIAD
F-269U
–
+
–
+
++
–
+
OUTIN LT1083-12 OUTIN
GND
C30B
C30B
3 4
20Ω
560Ω
20Ω
12
L
1mH
T2
1N4003
1N4148
1N4003
1N914
C1
50,000µF 100µF
LT1004-1.2
1N4003
1µF
0.1µF
1µF
100pF
16k*
16k*
11k*
11k*
12V
0A TO 7.5A
10k
82k 15k 2
2
2
3
3
3
8
8
–15V
–15V
–15V
15V
4
4
4
7
7
1
1
200k
15k
10k
2N3904
NC
8
6
7
1
LT1011
LT1011
LM301A
*
1% FILM RESISTOR
L-DALE TO-5 TYPE
T2-STANCOR 11Z-2003
REGULATOR WITH SCR PREREGULATOR TO
LOWER POWER DISSIPATION. ABOUT 1.7V
DIFFERENTIAL IS MAINTAINED ACROSS THE
LT1083 INDEPENDENT OF LOAD CURRENT.
LT1083/4/5 TA05
–
+
28V
INPUT
28V
470Ω
28V
4N28
1N914
1N914
LT1011
10k
10k
10k
1k 1M
MR1122
1mH
10,000µF
OUTPUT
LT1083-5 OUTIN
GND
LT1083/4/5 TA03
+
LT1083-5 OUTINVIN
VOUT = 5V
IOUT = 0A TO 15A
GND
LT1083-5
0.015Ω
OUT
2 FEET #18 WIRE*
IN
GND
*THE #18 WIRE ACTS
AS BALLAST RESISTANCE
INSURING CURRENT SHARING
BETWEEN BOTH DEVICES
LT1083/4/5 TA04
High Efficiency Regulator Paralleling Regulators
LT1083/LT1084/LT1085 Fixed
13
1083ffe
For more information www.linear.com/LT1083
OBSOLETE PACKAGE
K Package
2-Lead TO-3 Metal Can
(LTC DWG # 05-08-1310)
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
K2 (TO-3) 0801
.038 – .043
(0.965 – 1.09)
.060 – .135
(1.524 – 3.429)
.320 – .350
(8.13 – 8.89)
.420 – .480
(10.67 – 12.19)
.760 – .775
(19.30 – 19.69)
.490 – .510
(12.45 – 12.95)
R
.167 – .177
(4.24 – 4.49)
R
.151 – .161
(3.86 – 4.09)
DIA, 2PLCS
1.177 – 1.197
(29.90 – 30.40)
.655 – .675
(16.64 – 17.15)
.067 – .077
(1.70 – 1.96)
.210 – .220
(5.33 – 5.59)
.425 – .435
(10.80 – 11.05)
LT1083/LT1084/LT1085 Fixed
14
1083ffe
For more information www.linear.com/LT1083
T Package
3-Lead Plastic TO-220
(LTC DWG # 05-08-1420)
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
.100
(2.540)
BSC .028 – .038
(0.711 – 0.965)
T3 (TO-220) 0801
.045 – .055
(1.143 – 1.397)
.165 – .180
(4.191 – 4.572)
.095 – .115
(2.413 – 2.921)
.013 – .023
(0.330 – 0.584)
.520 – .570
(13.208 – 14.478)
.980 – 1.070
(24.892 – 27.178)
.218 – .252
(5.537 – 6.401)
.050
(1.270)
TYP
.147 – .155
(3.734 – 3.937)
DIA
.390 – .415
(9.906 – 10.541)
.330 – .370
(8.382 – 9.398)
.460 – .500
(11.684 – 12.700)
.570 – .620
(14.478 – 15.748)
.230 – .270
(5.842 – 6.858)
T Package
3-Lead Plastic TO-220
(Reference LTC DWG # 05-08-1420)
LT1083/LT1084/LT1085 Fixed
15
1083ffe
For more information www.linear.com/LT1083
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
M Package
3-Lead Plastic DD Pak
(LTC DWG # 05-08-1460 Rev F)
.050
(1.270)
.143 +.012
–.020
( )
3.632 +0.305
–0.508
.100
(2.54)
BSC
.013 – .023
(0.330 – 0.584)
.095 – .115
(2.413 – 2.921)
.004 +.008
–.004
( )
0.102 +0.203
–0.102
.050 ±.012
(1.270 ±0.305)
.059
(1.499)
.045 – .055
(1.143 – 1.397)
.165 – .180
(4.191 – 4.572)
.330 – .370
(8.382 – 9.398)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
15°
.300
(7.620)
.075
(1.905)
.183
(4.648)
.060
(1.524)
.060
(1.524)
.256
(6.502)
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
M (DD3) 0212 REV F
.420
.350
.585
.090
.070
.100
.420
.276
.325
.205
.080
.585
.090
.070
.100
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.320
M Package
3-Lead Plastic DD Pak
(Reference LTC DWG # 05-08-1460 Rev F)
DETAIL A
DETAIL A
0° – 7° TYP0° – 7° TYP
LT1083/LT1084/LT1085 Fixed
16
1083ffe
For more information www.linear.com/LT1083
OBSOLETE PACKAGE
P Package
3-Lead Plastic TO-3P (Similar to TO-247)
(LTC DWG # 05-08-1450 Rev A)
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
.170
(4.32)
MAX
.170 – .215
(4.32 – 5.46)
MOUNTING HOLE
.115 – .145
(2.92 – 3.68)
DIA
.580 – .600
(14.73 – 15.24)
.780 – .800
(19.81 – 20.32)
.620 – .640
(15.75 – 16.26)
.215
(5.46)
BSC
.113 – .123
(2.87 – 3.12)
.042 – .052
(1.07 – 1.32)
.074 – .084
(1.88 – 2.13)
.187 – .207
(4.75 – 5.26)
.060 – .081
(1.52 – 2.06)
18° – 22°
3° – 7°
.087 – .102
(2.21 – 2.59)
.020 – .040
(0.51 – 1.02)
EJECTOR PIN MARKS
.105 – .125
(2.67 – 3.18)
DIA
P3 0512 REV A
P Package
3-Lead Plastic TO-3P (Similar to TO-247))
(Reference LTC DWG # 05-08-1450 Rev A)
.560 – .620
(14.22 – 15.75)
.515 – .580
(13.08 – 14.73)
.305 – .370
(7.75 – 9.40)
.635 – .720
(16.13 – 18.29)
.104 – .145
(2.64 – 3.68)
.819 – .870
(20.80 – 22.10)
BOTTOM VIEW OF TO-3P
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
.265 – .293
(6.73 – 7.44)
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED .030" (.762mm)
LT1083/LT1084/LT1085 Fixed
17
1083ffe
For more information www.linear.com/LT1083
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.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
E 06/15 Obsolete TO-3P package. 2, 16
(Revision history begins at Rev E)
LT1083/LT1084/LT1085 Fixed
18
1083ffe
For more information www.linear.com/LT1083
LINEAR TECHNOLOGY CORPORATION 1994
LT 0615 REV E • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LT1083
relaTeD parTs
Typical applicaTion
VIN
50Ω
LT1084-5
LT1083/4/5 TA09
5.2V LINE
5.0V BATTERY
LT1084-5
SELECT
FOR
CHARGE
RATE
6.5V 100µF
10µF
10µF
+
++
Adjusting Output Voltage Regulator with Reference
V
IN
V
OUT
= –12V
LT1083/4/5 TA08
10,000µF
FLOATING INPUT
100µF
LT1084-12 OUTIN
GND
++
Low Dropout Negative Supply Battery Backed Up Regulated Supply
V
IN
> 12V LT1085-5
LT1083/4/5 TA06
5V to 10V
10µF
*OPTIONAL IMPROVES RIPPLE REJECTION
10µF* 1k
100µF
+
+
+
PART NUMBER DESCRIPTION COMMENTS
LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current
LT1175 500mA Negative Low Dropout Micropower Regulator 45µA IQ, 0.26V Dropout Voltage, SOT-223 Package
LT1185 3A Negative Low Dropout Regulator VIN: –4.5V to –35V, 0.8V Dropout Voltage, DD-Pak and TO-220 Packages
LT1529 3A Low Dropout Regulator with 50µA IQ500mV Dropout Voltage
LT1580 7A, Very Low Dropout Regulator 0.54V Dropout at 7A, Fixed 2.5VOUT and Adjustable
LT1581 10A, Very Low Dropout Regulator 0.63V Dropout at 10A, Fixed 2.5VOUT and Adjustable
LT1584/LT1585/
LT1587
7A/4.6A/3A Fast Response LDOs Fast Transient Response for Microprocessor Applications
LT1761 Series 100mA, Low Noise, Low Dropout Micropower Regulators
in SOT-23
20µA Quiescent Current, 20µVRMS Noise, SOT-23 Package
LT1762 Series 150mA, Low Noise, LDO Micropower Regulators 25µA Quiescent Current, 20µVRMS Noise, MSOP Package
LT1763 Series 500mA, Low Noise LDO Micropower Regulators 30µA Quiescent Current, 20µVRMS Noise, SO-8 Package
LT1764 3A Low Noise Fast Transient Response LDO 40µVRMS Noise, 5-Lead DD Package
LT1962 300mA, Low Noise LDO Micropower Regulator 20µVRMS Noise, MSOP Package
LT1963 1.5A, Low Noise, Fast Transient Response LDO 40µVRMS Noise, SOT-223 Package
LT1964 200mA, Low Noise, Negative LDO 340mV Dropout Voltage, Low Noise 30µVRMS, VIN = –1.8V to –20V, ThinSOT™
and 3mm × 3mm DFN-8 Packages
LT3015 1.5A, Low Noise, Negative Linear Regulator with Precision
Current Limit
VIN: –1.8V to –30V, VOUT: –1.22V to –29.5V, Dropout Voltage: 310mV, Precision
Current Limit with Foldback, Low Output Noise: 60μVRMS (10Hz to 100kHz),
TO-220, DD-Pak, DFN and MSOP Packages
LT3080/
LT3080-1
1.1A, Parallelable, Low Noise, Low Dropout Linear Regulator 300mV Dropout Voltage (2-Supply Operation), Low Noise: 40µVRMS,
VIN: 1.2V to 36V, VOUT: 0V to 35.7V, Stable with Ceramic Caps, TO-220,
DD-Pak, SOT-223, MS8E and 3mm × 3mm DFN-8 Packages; "-1" Version Has
Integrated Internal Ballast Resistor
LT3090 600mA Low Noise Negative LDO with Programmable ILIMIT 300mV Dropout Voltage, 18µVRMS Output Voltage Noise, Parallelable 50μA SET
Pin Current: ±1% Initial Accuracy, Positive/Negative Current Monitors Wide Input
Voltage Range: –1.5V to –36V, Rail-to-Rail Output Voltage Range: 0V to –32V
V
IN
> 11.5V
5V
OUT
LT1085-5
LT1029
LT1083/4/5 TA07
10V
10µF 100µF
++