LT1085CT-33 [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: | LT1085CT-33 |
厂家: | Linear |
描述: | 3A, 5A, 7.5A Low Dropout Positive Fixed Regulators |
文件: | 总12页 (文件大小:148K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1083/LT1084/LT1085 Fixed
3A, 5A, 7.5A Low Dropout
Positive Fixed Regulators
U
FEATURES
DESCRIPTIO
The LT®1083 series of positive adjustable regulators are
designedtoprovide3A, 5Aand7.5Awithhigherefficiency
than currently available devices. All internal circuitry is
■
Three-Terminal 3.3V, 3.6V, 5V and 12V
■
Output Current of 3A, 5A or 7.5A
■
Operates Down to 1V Dropout
■
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
U
APPLICATIO S
■
High Efficiency Linear Regulators
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.
■
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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
U
TYPICAL APPLICATIO
5V, 7.5A Regulator
Dropout Voltage vs Output Current
2
V
≥ 6.5V
5V AT 7.5A
LT1083-5
IN
+
+
22μF*
TANTALUM
10μF
LT1083/4/5 TA01
1
0
*REQUIRED FOR STABILITY
0
I
/2
I
FULLLOAD
FULLLOAD
OUTPUT CURRENT (A)
1083/4/5 TA02
1083ffd
1
LT1083/LT1084/LT1085 Fixed
W W U W
ABSOLUTE AXI U RATI GS
(Note 1)
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
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
*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.
Control Section .............................. 0°C to 125°C
Power Transistor............................ 0°C to 150°C
“M” Grades
U
U U
PRECO DITIO I G
100% Thermal Limit Functional Test.
Control Section .......................... –55°C to 150°C
Power Transistor........................ –55°C to 200°C
U W
U
PACKAGE/ORDER I FOR ATIO
ORDER PART NUMBER
ORDER PART NUMBER
CASE IS
OUTPUT
V
IN
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
2
1
FRONT VIEW
TAB IS
OUTPUT
3
2
1
V
V
IN
GND
OUT
K PACKAGE
2-LEAD TO-3 METAL CAN
GND
θJA = 35°C/W
P PACKAGE
3-LEAD TO-3P PLASTIC
θ
JA = 45°C/W
OBSOLETE NOT RECOMMENDED
FOR NEW DESIGNS
FRONT VIEW
LT1084CT-3.3
LT1085CM-3.3
LT1085CM-3.6
LT1085IM-3.6
FRONT VIEW
3
2
1
V
LT1084CT-5
IN
TAB IS
OUTPUT
TAB IS
OUTPUT
LT1084CT-12
LT1085CT-3.3
LT1085CT-3.6
LT1085CT-5
LT1085CT-12
V
OUT
3
2
1
V
V
IN
GND
OUT
M PACKAGE
3-LEAD PLASTIC DD
GND
θ
JA = 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.
T PACKAGE
3-LEAD PLASTIC TO-220
θ
JA = 50°C/W
Consult factory for parts specified with wider operating temperature ranges.
1083ffd
2
LT1083/LT1084/LT1085 Fixed
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Voltage
LT1084-3.3
I
= 0mA, T = 25°C, V = 8V (K Package Only)
3.270
3.235
3.300
3.300
3.330
3.365
V
V
OUT
J
IN
4.8V ≤ V ≤ 15V, 0 ≤ I
≤ I (Notes 3, 4, 9)
FULLOAD
●
●
●
●
IN
OUT
LT1085-3.3
LT1085-3.6
V
= 5V, I
= 0mA, T = 25°C (K Package Only)
3.270
3.235
3.300
3.300
3.330
3.365
V
V
IN
OUT
J
4.8V ≤ V ≤ 15V, 0 ≤ I
≤ I
(Notes 3, 4, 9)
FULLOAD
IN
OUT
V
= 5V, I
IN
IN
= 0mA, T = 25°C (K Package Only)
3.564
3.500
3.528
3.600
3.636
3.672
3.672
V
V
V
IN
OUT
J
5V ≤ V ≤ 15V, 0 ≤ I
≤ I
≤ I
(Note 9)
OUT
FULLOAD
5V ≤ V ≤ 15V, 0 ≤ I
, TJ ≥ 0°C (Notes 3, 4, 9)
OUT
FULLOAD
LT1085-3.6
5V ≤ V ≤ 15V, 0 ≤ I
≤ 2.5A (Notes 3, 4, 9)
J
3.528
3.350
3.450
3.528
3.672
3.672
3.672
3.672
V
V
V
V
IN
OUT
V
V
V
= 4.75V, I
= 4.75V, I
= 4.75V, I
= 3A, T ≥ 0°C
IN
IN
IN
OUT
OUT
OUT
= 2.5A, T ≥ 0°C
J
= 1.5A, T > 0°C
J
LT1083/4/5-5
I
= 0mA, T = 25°C, V = 8V (K Package Only)
4.950
4.900
5.000
5.000
5.050
5.100
V
V
OUT
0 ≤ I
J
IN
≤ I
, 6.5V ≤ V ≤ 20V (Notes 4, 6, 7, 9)
OUT
FULLOAD IN
LT1083/4/5-12 I
= 0mA, T = 25°C, V = 15V (K Package Only)
11.880 12.000 12.120
11.760 12.000 12.240
V
V
OUT
0 ≤ I
J
IN
≤ I
, 13.5V ≤ V ≤ 25V (Notes 4, 6, 7, 9)
OUT
FULLOAD IN
Line Regulation
LT1084-3.3
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
I
= 0mA, T = 25°C, 4.8V ≤ V ≤ 15V
0.5
1.0
6
6
mV
mV
OUT
J
IN
●
●
●
●
●
●
●
●
●
4.8V ≤ V ≤ 15V, I
= 0mA, T = 25°C
0.5
1.0
6
6
mV
mV
IN
OUT
J
4.8V ≤ V ≤ 15V, I
= 0mA, T = 25°C
0.5
1.0
6
6
mV
mV
IN
OUT
J
I
= 0mA, T = 25°C, 6.5V ≤ V ≤ 20V (Notes 2, 3)
0.5
1.0
10
10
mV
mV
OUT
OUT
J
IN
LT1083/4/5-12 I
= 0mA, T = 25°C, 13.5V ≤ V ≤ 25V (Notes 2, 3)
1.0
2.0
25
25
mV
mV
J
IN
Load Regulation
LT1084-3.3
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
V
= 5V, 0 ≤ I
≤ 5A, T = 25°C
3
7
15
20
mV
mV
IN
IN
IN
IN
OUT
J
V
V
V
= 5V, 0 ≤ I
≤ 3A, T = 25°C
3
7
15
20
mV
mV
OUT
J
= 5.25V, 0 ≤ I
≤ 3A, T = 25°C
3
7
15
20
mV
mV
OUT
J
= 8V, 0 ≤ I
≤ I T = 25°C (Notes 2, 3, 4, 6)
FULLLOAD, J
5
10
20
35
mV
mV
OUT
LT1083/4/5-12 V = 15V, 0 ≤ I
≤ I T = 25°C (Notes 2, 3, 4, 6)
FULLLOAD, J
12
24
36
72
mV
mV
IN
OUT
●
●
●
●
●
●
●
●
●
●
●
●
●
Dropout Voltage
Current Limit
LT1084/5-3.3 ΔV
= 33mV, I
= I
(Notes 5, 6)
(Notes 5, 6)
(Notes 5, 6)
1.3
1.3
1.3
1.3
9.5
9.5
6.5
6.5
6.5
4.0
4.0
4.0
1.5
1.5
1.5
1.5
V
V
V
V
A
A
A
A
A
A
A
A
OUT
OUT
OUT
OUT
OUT
FULL LOAD
FULL LOAD
FULL LOAD
LT1085-3.6
ΔV
= 36mV, I
= 50mV, I
= I
= I
OUT
OUT
LT1083/4/5-5 ΔV
LT1083/4/5-12 ΔV
= 120mV, I
= I
(Notes 5, 6)
FULL LOAD
OUT
LT1083-5
LT1083-12
LT1084-3.3
LT1084-5
LT1084-12
V
V
V
V
V
= 10V
8.0
8.0
5.5
5.5
5.5
3.2
3.2
3.2
IN
IN
IN
IN
IN
= 17V
= 8V
= 10V
= 17V
LT1085-3.3/3.6 V = 8V
IN
LT1085-5
V
V
= 10V
= 17V
IN
IN
LT1085-12
1083ffd
3
LT1083/LT1084/LT1085 Fixed
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
PARAMETER
CONDITIONS
LT1084-3.3
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
LT1083/4/5-12
MIN
TYP
5.0
5.0
5.0
5.0
5.0
MAX
10.0
10.0
10.0
10.0
10.0
UNITS
mA
Quiescient Current
V
V
V
V
V
= 18V
= 18V
= 18V
≤ 20V
≤ 25V
●
●
●
●
●
IN
IN
IN
IN
IN
mA
mA
mA
mA
Thermal Regulation
Ripple Rejection
LT1083-5/12
T = 25°C, 30ms pulse
0.002
0.003
0.004
0.010
0.015
0.020
%/W
%/W
%/W
A
LT1084-3.3/5/12
LT1085-3.3/3.6/5/12
f = 120Hz, C
LT1084-3.3
LT1085-3.3
LT1085-3.6
= 25μF Tantalum, I
= I
(Note 4)
FULLLOAD
OUT
OUT
f = 120Hz, C
f = 120Hz, C
f = 120Hz, C
= 25μF Tantalum, I
= 5A, V = 6.3V
●
●
●
●
●
60
60
60
60
54
72
72
72
68
60
dB
dB
dB
dB
dB
OUT
OUT
OUT
OUT
IN
IN
IN
= 25μF Tantalum, V = 6.3V, I
= 3A
= 3A
OUT
OUT
= 25μF Tantalum, V = 6.6V, I
LT1083/4/5-5
LT1083/4/5-12
V
V
= 8V (Note 6)
= 15V (Note 6)
IN
IN
Temperature Stability
Long Term Stability
RMS Output Noise
●
0.5
%
%
T = 125°C, 1000 Hrs.
0.03
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
LT1084
K Package
P Package
0.6/1.6
0.5/1.6
°C/W
°C/W
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 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
T ≥ – 40°C.
J
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.
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 7: 1.7V ≤ (V – V ) ≤ 25V for LT1084 at –55°C ≤ T ≤ – 40°C.
IN
OUT
J
Note 8: Dropout voltage 1.7V maximum for LT1084 at
–55°C ≤ T ≤ –40°C.
J
Note 9: Full load current is not available at all input-output voltages.
See Notes 3, 4, 6.
Note 4: 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
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.
1083ffd
4
LT1083/LT1084/LT1085 Fixed
TYPICAL PERFOR A CE CHARACTERISTICS
U W
LT1083 Dropout Voltage
LT1083 Short-Circuit Current
LT1083 Load Regulation
0.10
0.05
2
12
10
8
ΔI = 7.5A
INDICATES GUARANTEED TEST POINT
–40°C ≤ T ≤ 150°C
25°C
J
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
20
30
35
0
1
2
3
4
5
6
7
8
9
10
0
5
15
25
OUTPUT CURRENT (A)
LT1083/4/5 FIXED G03
LT1083/4/5 FIXED G01
LT1083/4/5 FIXED G02
LT1084 Dropout Voltage
LT1084 Short Circuit Current
LT1084 Load Regulation
10
9
8
7
6
5
4
3
2
1
0
0.10
0.05
2
ΔI = 5A
INDICATES GUARANTEED TEST POINT
–55°C ≤ T ≤ 150°C
J
0°C ≤ T ≤ 125°C
J
150°C
25°C
0
–55°C
–0.05
–0.10
–0.15
–0.20
1
T
= –55°C
J
T
= 25°C
J
T
= 150°C
J
I
FULL LOAD
GUARANTEED
0
2
75 100
–50 –25
0
25 50
125 150
0
10
15
20
25
30
35
5
0
1
3
4
5
6
2
TEMPERATURE (°C)
INPUT/OUTPUT DIFFERENTIAL (V)
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
ΔI = 3A
INDICATES GUARANTEED TEST POINT
–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
1
0
T
= –55°C
J
T
= 25°C
–55°C
J
T
= 150°C
2
1
0
J
I
FULL LOAD
GUARANTEED
75 100
–50 –25
0
25 50
125 150
0
2
3
1
4
20
30
35
0
5
10
15
25
TEMPERATURE (°C)
OUTPUT CURRENT (A)
INPUT/OUTPUT DIFFERENTIAL (V)
LT1083/4/5 FIXED G09
LT1083/4/5 FIXED G07
LT1083/4/5 FIXED G08
1083ffd
5
LT1083/LT1084/LT1085 Fixed
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LT1083/4/5-5 Ripple Rejection
vs Current
LT1083/4/5-5 Ripple Rejection
Temperature Stability
100
90
80
70
60
50
40
30
20
10
0
80
70
60
50
2.0
1.0
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
20
10
0
–1.0
I
= I
OUT FULLLOAD
–2.0
10
100
1k
10k
100k
0
0.8
1.0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
0.2
0.4
0.6
FREQUENCY (Hz)
OUTPUT CURRENT (0 TO I
)
FULLLOAD
1083/4/5 FIXED G10
1083/4/5 FIXED G11
LT1183/4/5 FIXED G12
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
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
≤ 3V
P-P
(V – V ) ≥ 3V
IN
OUT
LT1083MK
f
= 20kHz
RIPPLE
R
40
30
V
≤ 0.5V
P-P
(V – V ) ≥ V
DROPOUT
IN
OUT
LT1083CP
20
10
0
LT1083CK
I
= I
OUT FULLLOAD
10
100
1k
10k
100k
0
0.8
1.0
50 60 70 80 90 100 110 120 130 140 150
0.2
0.4
0.6
FREQUENCY (Hz)
OUTPUT CURRENT (0 TO I
)
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
FULLLOAD
1083/4/5 FIXED G13
1083/4/5 FIXED G14
LT1083/4/5 FIXED G15
LT1084 Maximum Power
Dissipation*
LT1085 Maximum Power
Dissipation*
60
50
40
30
20
10
0
50
40
30
20
10
0
LT1084MK
LT1084CP
LT1085MK
LT1084CT
LT1085CT
LT1084CK
LT1085CK
50 60 70 80 90 100 110 120 130 140 150
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
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
1083ffd
6
LT1083/LT1084/LT1085 Fixed
W
BLOCK DIAGRA
V
IN
+
–
THERMAL
LIMIT
V
OUT
GND
LT1083/4/5 BD
W U U
U
APPLICATIO S I FOR ATIO
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.
Another possible stability problem that can occur in
monolithic 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 resistance since increasing voltage causes
current to decrease. Negitive resistance during current
limit is not unique to the LT1083 series and has been
present on all power IC regulators. The value of negative
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-
resistance is a function of how fast the current limit is
1083ffd
7
LT1083/LT1084/LT1085 Fixed
W U U
U
APPLICATIO S I FOR ATIO
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
doesnotcauseanyproblemswiththeICregulatorandcan
usually be ignored.
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
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.
IN
OUT
LT1083
ADJ
V
OUT
V
IN
+
C
OUT
150μF
1083/4/5 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
conditionshowever, maximumjunctiontemperaturerat-
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,
When power is first turned on, as the input voltage rises,
the output follows the input, allowing the regulator to start
1083ffd
8
LT1083/LT1084/LT1085 Fixed
W U U
APPLICATIO S I FOR ATIO
U
case-to-heatsinkinterface,andheatsinkresistanceitself.
New thermal resistance specifications have been devel-
oped to more accurately reflect device temperature and
ensure safe operating temperatures. The data section for
these new regulators provides a separate thermal resis-
tance and maximum junction temperature for both the
Control Section and the Power Section. Previous regula-
tors, with a single junction-to-case thermal resistance
specification, used an average of the two values provided
here and therefore could allow excessive junction tem-
peratures under certain conditions of ambient tempera-
ture 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 LT1083-5CP (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
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 < 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 APPLICATIO S
High Efficiency Regulator
Paralleling Regulators
1mH
2 FEET #18 WIRE*
28V
INPUT
OUTPUT
IN
LT1083-5 OUT
GND
V
IN
IN
LT1083-5 OUT
GND
IN
+
10,000μF
MR1122
V
= 5V
= 0A TO 15A
470Ω
1N914
OUT
OUT
10k
I
0.015Ω
28V
LT1083-5 OUT
GND
*THE #18 WIRE ACTS
AS BALLAST RESISTANCE
INSURING CURRENT SHARING
BETWEEN BOTH DEVICES
1k
1M
4N28
10k
LT1083/4/5 TA04
LT1083/4/5 TA03
+
–
LT1011
10k
28V
1N914
1083ffd
9
LT1083/LT1084/LT1085 Fixed
U
TYPICAL APPLICATIO S
7.5A Regulator
T1
L
1MH
TRIAD
C30B
F-269U
12V
IN
LT1083-12 OUT
GND
0A TO 7.5A
+
C1
50,000μF
20Ω
+
T2
1N4003
3
4
2
100μF
110VAC
20Ω
1
LT1004-1.2
C30B
1N4003
1N4003
1N914
16k*
16k*
1μF
560Ω
15V
82k
10k
8
15k
–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
*
6
+
T2-STANCOR 11Z-2003
1
–
7
15k
15V
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.
LT1083/4/5 TA05
1μF
U
PACKAGE DESCRIPTIO
T Package
K Package
2-Lead TO-3 Metal Can
(LTC DWG # 05-08-1310)
3-Lead Plastic TO-220
(LTC DWG # 05-08-1420)
.760 – .775
(19.30 – 19.69)
.147 – .155
(3.734 – 3.937)
DIA
.320 – .350
(8.13 – 8.89)
.165 – .180
(4.191 – 4.572)
.390 – .415
(9.906 – 10.541)
.045 – .055
.060 – .135
(1.143 – 1.397)
(1.524 – 3.429)
.230 – .270
(5.842 – 6.858)
.420 – .480
.570 – .620
(10.67 – 12.19)
.460 – .500
(14.478 – 15.748)
(11.684 – 12.700)
.330 – .370
(8.382 – 9.398)
.038 – .043
(0.965 – 1.09)
.980 – 1.070
(24.892 – 27.178)
1.177 – 1.197
(29.90 – 30.40)
.520 – .570
(13.208 – 14.478)
.655 – .675
(16.64 – 17.15)
.218 – .252
(5.537 – 6.401)
.210 – .220
(5.33 – 5.59)
.151 – .161
(3.86 – 4.09)
DIA, 2PLCS
.013 – .023
.100
(2.540)
BSC
(0.330 – 0.584)
.095 – .115
(2.413 – 2.921)
T3 (TO-220) 0801
.050
(1.270)
TYP
.167 – .177
(4.24 – 4.49)
R
.028 – .038
(0.711 – 0.965)
.425 – .435
(10.80 – 11.05)
.067 – .077
(1.70 – 1.96)
.490 – .510
(12.45 – 12.95)
R
K2 (TO-3) 0801
OBSOLETE PACKAGE
1083ffd
10
LT1083/LT1084/LT1085 Fixed
U
PACKAGE DESCRIPTIO
M Package
3-Lead Plastic DD Pak
(LTC DWG # 05-08-1460)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
.060
.256
.165 – .180
(4.191 – 4.572)
(1.524)
(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
.420
.276
.080
.420
.350
.325
.205
.320
.565
.565
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.090
.090
M (DD3) 0204
.100
.070
.100
.070
RECOMMENDED SOLDER PAD LAYOUT
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
P Package
3-Lead Plastic TO-3P (Similar to TO-247)
(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
(21.08 – 22.10)
.170 – .2OO
(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)
1083ffd
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/LT1084/LT1085 Fixed
U
TYPICAL APPLICATIO S
Adjusting Output Voltage
Regulator with Reference
V
IN
> 12V
V
> 11.5V
IN
10V
100μF
LT1085-5
LT1085-5
5V to 10V
100μF
+
+
+
+
10μF
10μF
5V
OUT
+
LT1029
1k
10μF*
LT1083/4/5 TA07
LT1083/4/5 TA06
*OPTIONAL IMPROVES RIPPLE REJECTION
Low Dropout Negative Supply
Battery Backed Up Regulated Supply
5.2V LINE
5.0V BATTERY
V
IN
LT1084-5
+
IN LT1084-12 OUT
GND
V
IN
10μF
50Ω
SELECT
FOR
CHARGE
RATE
+
+
100μF
10,000μF
V
= –12V
OUT
LT1084-5
LT1083/4/5 TA08
FLOATING INPUT
+
+
6.5V
10μF
100μF
LT1083/4/5 TA09
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
50μA Quiescent Current
LT1129
700mA Micropower Low Dropout Regulator
LT1175
500mA Negative Low Dropout Micropower Regulator
4.5A, 500kHz Step-Down Converter
45μA I , 0.26V Dropout Voltage, SOT-223 Package
4.5A, 0.07Ω Internal Switch, SO-8 Package
500mV Dropout Voltage
Q
LT1374
LT1529
3A Low Dropout Regulator with 50μA I
Q
LT1573
UltraFastTM Transient Response Low Dropout Regulator
UltraFast Transient Response Low Dropout Regulator
7A, Very Low Dropout Regulator
Drives External PNP
LT1575
Drives External N-Channel MOSFET
LT1580
0.54V Dropout at 7A, Fixed 2.5V
and Adjustable
OUT
LT1581
10A, Very Low Dropout Regulator
0.63V Dropout at 10A, Fixed 2.5V
and Adjustable
OUT
LT1584/85/87
LT1735
7A/4.6A/3A Fast Response LDOs
Fast Transient Response for Microprocessor Applications
High Efficiency, OPTI-LOOPTM Compensation
Synchronous Step-Down Converter
LT1761 Series
LT1762 Series
LT1763 Series
LT1764
100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20μA Quiescent Current, 20μV
Noise, SOT-23 Package
Noise, MSOP Package
Noise, SO-8 Package
RMS
RMS
RMS
150mA, Low Noise, LDO Micropower Regulators
500mA, Low Noise LDO Micropower Regulators
3A Low Noise Fast Transient Response LDO
300mA, Low Noise LDO Micropower Regulator
1.5A, Low Noise, Fast Transient Response LDO
25μA Quiescent Current, 20μV
30μA Quiescent Current, 20μV
40μV
20μV
40μV
Noise, 5-Lead DD Package
Noise, MSOP Package
RMS
RMS
RMS
LT1962
LT1963
Noise, SOT-223 Package
UltraFast and OPTI-LOOP are trademarks of Linear Technology Corporation.
1083ffd
LT 1007 REV D • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
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