Linear LT1085CM-3.3 3a, 5a, 7.5a low dropout positive fixed regulator Datasheet

LT1083/LT1084/LT1085 Fixed
3A, 5A, 7.5A Low Dropout
Positive Fixed Regulators
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FEATURES
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DESCRIPTIO
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
Line Regulation: 0.015%
Load Regulation: 0.1%
100% Thermal Limit Functional Test
Adjustable Versions Available
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APPLICATIO S
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High Efficiency Linear Regulators
Post Regulators for Switching Supplies
Constant Current Regulators
Battery Chargers
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.
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.
Unlike PNP regulators, where up to 10% of the output
current is wasted as quiescent current, the LT1083 quiescent current flows into the load, increasing efficiency.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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TYPICAL APPLICATIO
5V, 7.5A Regulator
5V AT 7.5A
LT1083-5
+
+
10μF
22μF*
TANTALUM
LT1083/4/5 TA01
*REQUIRED FOR STABILITY
INPUT/OUTPUT VOLTAGE DIFFERENTIAL (V)
VIN ≥ 6.5V
Dropout Voltage vs Output Current
2
1
0
0
IFULLLOAD/2
OUTPUT CURRENT (A)
IFULLLOAD
1083/4/5 TA02
1083ffd
1
LT1083/LT1084/LT1085 Fixed
(Note 1)
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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
“M” Grades
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
*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.
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RATI GS
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ABSOLUTE
PRECO DITIO I G
100% Thermal Limit Functional Test.
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PACKAGE/ORDER I FOR ATIO
CASE IS
OUTPUT
VIN
ORDER PART NUMBER
LT1083CK-5
LT1083CK-12
LT1083MK-5
LT1083MK-12
LT1084CK-5
LT1084CK-12
2
1
GND
K PACKAGE
2-LEAD TO-3 METAL CAN
LT1084MK-5
LT1084MK-12
LT1085CK-5
LT1085CK-12
LT1085MK-5
LT1085MK-12
ORDER PART NUMBER
TAB IS
OUTPUT
θJA = 35°C/W
3
VIN
2
VOUT
1
GND
LT1083CP-5
LT1083CP-12
LT1084CP-5
LT1084CP-12
P PACKAGE
3-LEAD TO-3P PLASTIC
OBSOLETE NOT RECOMMENDED
FOR NEW DESIGNS
TAB IS
OUTPUT
FRONT VIEW
FRONT VIEW
3
VIN
2
VOUT
1
GND
LT1084CT-3.3
LT1084CT-5
LT1084CT-12
LT1085CT-3.3
LT1085CT-3.6
LT1085CT-5
LT1085CT-12
T PACKAGE
3-LEAD PLASTIC TO-220
θJA = 50°C/W
θJA = 45°C/W
FRONT VIEW
TAB IS
OUTPUT
3
VIN
2
VOUT
1
GND
LT1085CM-3.3
LT1085CM-3.6
LT1085IM-3.6
M PACKAGE
3-LEAD PLASTIC DD
θJA = 30°C/W*
*WITH PACKAGE SOLDERED TO 0.52IN2
COPPER AREA OVER BACKSIDE GROUND
PLANE OR INTERNAL POWER PLANE. θJA CAN
VARY FROM 20°C/W TO > 40°C/W DEPENDING
ON MOUNTING TECHNIQUE.
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
Output Voltage
LT1084-3.3
LT1085-3.3
LT1085-3.6
3.300
3.300
3.330
3.365
V
V
VIN = 5V, IOUT = 0mA, TJ = 25°C (K Package Only)
4.8V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULLOAD (Notes 3, 4, 9)
●
3.270
3.235
3.300
3.300
3.330
3.365
V
V
3.564
3.500
3.528
3.600
3.636
3.672
3.672
V
V
V
3.672
3.672
3.672
3.672
V
V
V
V
VIN = 5V, IOUT = 0mA, TJ = 25°C (K Package Only)
5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULLOAD (Note 9)
5V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULLOAD, TJ ≥ 0°C (Notes 3, 4, 9)
LT1083/4/5-5
IOUT = 0mA, TJ = 25°C, VIN = 8V (K Package Only)
0 ≤ IOUT ≤ IFULLOAD, 6.5V ≤ VIN ≤ 20V (Notes 4, 6, 7, 9)
LT1085-3.6
LT1083/4/5-5
IOUT = 0mA, TJ = 25°C, 4.8V ≤ VIN ≤ 15V
4.8V ≤ VIN ≤ 15V, IOUT = 0mA, TJ= 25°C
4.8V ≤ VIN ≤ 15V, IOUT = 0mA, TJ= 25°C
IOUT = 0mA, TJ = 25°C, 6.5V ≤ VIN ≤ 20V (Notes 2, 3)
LT1083/4/5-12 IOUT = 0mA, TJ = 25°C, 13.5V ≤ VIN ≤ 25V (Notes 2, 3)
Load Regulation
LT1084-3.3
LT1085-3.3
LT1085-3.6
LT1083/4/5-5
VIN = 5V, 0 ≤ IOUT ≤ 5A, TJ = 25°C
VIN = 5V, 0 ≤ IOUT ≤ 3A, TJ = 25°C
VIN = 5.25V, 0 ≤ IOUT ≤ 3A, TJ = 25°C
VIN = 8V, 0 ≤ IOUT ≤ IFULLLOAD, TJ = 25°C (Notes 2, 3, 4, 6)
LT1083/4/5-12 VIN = 15V, 0 ≤ IOUT ≤ IFULLLOAD, TJ = 25°C (Notes 2, 3, 4, 6)
Dropout Voltage
Current Limit
UNITS
3.270
3.235
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
LT1085-3.3
MAX
●
LT1085-3.6
LT1084-3.3
TYP
IOUT = 0mA, TJ = 25°C, VIN = 8V (K Package Only)
4.8V ≤ VIN ≤ 15V, 0 ≤ IOUT ≤ IFULLOAD (Notes 3, 4, 9)
●
●
3.528
3.350
3.450
3.528
4.950
4.900
5.000
5.000
5.050
5.100
V
V
11.880
11.760
12.000
12.000
12.120
12.240
V
V
●
0.5
1.0
6
6
mV
mV
●
0.5
1.0
6
6
mV
mV
●
0.5
1.0
6
6
mV
mV
●
0.5
1.0
10
10
mV
mV
●
1.0
2.0
25
25
mV
mV
●
3
7
15
20
mV
mV
●
3
7
15
20
mV
mV
●
3
7
15
20
mV
mV
●
5
10
20
35
mV
mV
●
12
24
36
72
mV
mV
LT1083/4/5-12 IOUT = 0mA, TJ = 25°C, VIN = 15V (K Package Only)
0 ≤ IOUT ≤ IFULLOAD, 13.5V ≤ VIN ≤ 25V (Notes 4, 6, 7, 9)
Line Regulation
MIN
LT1084/5-3.3
ΔVOUT = 33mV, IOUT = IFULL LOAD (Notes 5, 6)
●
1.3
1.5
V
LT1085-3.6
ΔVOUT = 36mV, IOUT = IFULL LOAD (Notes 5, 6)
●
1.3
1.5
V
LT1083/4/5-5
ΔVOUT = 50mV, IOUT = IFULL LOAD (Notes 5, 6)
●
1.3
1.5
V
LT1083/4/5-12 ΔVOUT = 120mV, IOUT = IFULL LOAD (Notes 5, 6)
●
1.3
1.5
V
LT1083-5
VIN = 10V
●
8.0
9.5
A
LT1083-12
VIN = 17V
●
8.0
9.5
A
LT1084-3.3
VIN = 8V
●
5.5
6.5
A
LT1084-5
VIN = 10V
●
5.5
6.5
A
LT1084-12
VIN = 17V
●
5.5
6.5
A
LT1085-3.3/3.6 VIN = 8V
LT1085-5
VIN = 10V
●
3.2
4.0
A
●
3.2
4.0
A
LT1085-12
●
3.2
4.0
A
VIN = 17V
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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
TYP
MAX
UNITS
Quiescient Current
LT1084-3.3
VIN = 18V
●
MIN
5.0
10.0
mA
LT1085-3.3
VIN = 18V
●
5.0
10.0
mA
LT1085-3.6
VIN = 18V
●
5.0
10.0
mA
LT1083/4/5-5
VIN ≤ 20V
●
5.0
10.0
mA
LT1083/4/5-12
VIN ≤ 25V
●
5.0
10.0
mA
0.002
0.003
0.004
0.010
0.015
0.020
%/W
%/W
%/W
Thermal Regulation
LT1083-5/12
TA = 25°C, 30ms pulse
LT1084-3.3/5/12
LT1085-3.3/3.6/5/12
Ripple Rejection
f = 120Hz, COUT = 25μF Tantalum, IOUT = IFULLLOAD (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)
●
●
●
●
●
●
Temperature Stability
60
60
60
60
54
72
72
72
68
60
dB
dB
dB
dB
dB
0.5
%
Long Term Stability
TA = 125°C, 1000 Hrs.
0.03
RMS Output Noise
(% of VOUT)
TA = 25°C,
10Hz = ≤ f ≤ 10kHz
0.003
Thermal Resistance
Junctrion-to-Case
Control Circuitry/Power Transistor (See Applications Information)
LT1083
K Package
P Package
1.0
%
%
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 IFULLLOAD
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.
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LT1083/LT1084/LT1085 Fixed
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TYPICAL PERFOR A CE CHARACTERISTICS
LT1083 Short-Circuit Current
–40°C ≤ TJ ≤ 150°C
0°C ≤ TJ ≤ 125°C
1
TJ = 150°C
TJ = 25°C
TJ = –55°C
25°C
10
150°C
8
6
–55°C
4
2
IFULL LOAD
GUARANTEED
1
2
3 4 5 6 7 8
OUTPUT CURRENT (A)
9
10
0
20
30
15
25
5
10
INPUT/OUTPUT DIFFERENTIAL (V)
LT1084 Dropout Voltage
35
TJ = –55°C
TJ = 25°C
7
150°C
25°C
6
–55°C
5
4
3
IFULL LOAD
GUARANTEED
2
5
0
6
20
15
10
25
30
5
INPUT/OUTPUT DIFFERENTIAL (V)
0.05
0
–0.05
–0.10
–0.15
35
LT1085 Dropout Voltage
SHORT-CIRCUIT CURRENT (A)
TJ = 25°C
TJ = 150°C
0
OUTPUT VOLTAGE DEVIATION (%)
INDICATES GUARANTEED TEST POINT
3
2
1
OUTPUT CURRENT (A)
LT1085 Load Regulation
0.10
6
TJ = –55°C
5
25°C
4
150°C
3
–55°C
2
IFULL LOAD
GUARANTEED
1
0
4
LT1083/4/5 FIXED G07
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 FIXED G06
LT1085 Short-Circuit Current
2
0°C ≤ TJ ≤ 125°C
0
LT1083/4/5 FIXED G05
LT1083/4/5 FIXEDG04
–55°C ≤ TJ ≤ 150°C
25 50 75 100 125 150
TEMPERATURE (°C)
ΔI = 5A
–0.20
–50 –25
0
0
3
4
2
OUTPUT CURRENT (A)
0
LT1084 Load Regulation
8
1
0
–0.15
0.10
OUTPUT VOLTAGE DEVIATION (%)
SHORT-CIRCUIT CURRENT (A)
1
1
–0.10
9
0°C ≤ TJ ≤ 125°C
1
–0.05
LT1084 Short Circuit Current
INDICATES GUARANTEED TEST POINT
0
0
LT1083/4/5 FIXED G03
10
TJ = 150°C
0.05
LT1083/4/5 FIXED G02
2
–55°C ≤ TJ ≤ 150°C
ΔI = 7.5A
–0.20
–50 –25
0
0
LT1083/4/5 FIXED G01
MINIMUN INPUT/OUTPUT DIFFERENTIAL (V)
OUTPUT VOLTAGE DEVIATION (%)
INDICATES GUARANTEED TEST POINT
0
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
LT1083 Load Regulation
0.10
12
SHORT-CIRCUIT CURRENT (A)
MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)
LT1083 Dropout Voltage
2
0
20
30
15
25
5
10
INPUT/OUTPUT DIFFERENTIAL (V)
35
LT1083/4/5 FIXED G08
ΔI = 3A
0.05
0
–0.05
–0.10
–0.15
–0.20
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083/4/5 FIXED G09
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LT1083/LT1084/LT1085 Fixed
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TYPICAL PERFOR A CE CHARACTERISTICS
LT1083/4/5-5 Ripple Rejection
vs Current
LT1083/4/5-5 Ripple Rejection
70
VRIPPLE
≤ 0.5VP-P
60
(VIN – VOUT) ≥ 3V
50
2.0
90
80
(VIN – VOUT) ≥ VDROPOUT
40
30
20
OUTPUT VOLTAGE CHANGE (%)
VRIPPLE ≤ 3VP-P
Temperature Stability
100
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
80
fR = 120Hz
VRIPPLE ≤ 3VP-P
70
fR = 20kHz
VRIPPLE ≤ 0.5VP-P
60
50
40
30
20
10
0
100k
0
0.8
0.2
0.6
0.4
OUTPUT CURRENT (0 TO IFULLLOAD)
1083/4/5 FIXED G10
–2.0
–50 –25
1.0
100
100
90
90
30
(VIN – VOUT) ≥ VDROPOUT
20
10
IOUT = IFULLLOAD
0
10
100
1k
10k
FREQUENCY (Hz)
100k
80
fR = 120Hz
VRIPPLE ≤ 3VP-P
70
70
POWER (W)
40
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
(VIN – VOUT) ≥ 3V
50
25 50 75 100 125 150
TEMPERATURE (°C)
LT1083 Maximum Power
Dissipation*
80
60
0
LT1183/4/5 FIXED G12
LT1083/4/5-12 Ripple Rejection
vs Current
VRIPPLE
≤ 0.5VP-P
70
–1.0
1083/4/5 FIXED G11
LT1083/4/5-12 Ripple Rejection
VRIPPLE ≤ 3VP-P
0
10
IOUT = IFULLLOAD
0
10
100
1k
10k
FREQUENCY (Hz)
80
1.0
60
fR = 20kHz
VRIPPLE ≤ 0.5VP-P
50
40
50
40
30
30
20
20
10
10
0
0
0
0.8
0.2
0.6
0.4
OUTPUT CURRENT (0 TO IFULLLOAD)
1083/4/5 FIXED G13
1.0
1083/4/5 FIXED G14
LT1083MK
60
LT1083CP
LT1083CK
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1083/4/5 FIXED G15
LT1085 Maximum Power
Dissipation*
LT1084 Maximum Power
Dissipation*
60
50
50
40
LT1084MK
30
LT1084CT
LT1084CP
20
10
POWER (W)
POWER (W)
40
30
LT1085MK
20
LT1085CT
10
LT1084CK
LT1085CK
0
0
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
50 60 70 80 90 100 110 120 130 140 150
CASE TEMPERATURE (°C)
* AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE
LT1083/4/5 FIXED G16
LT1083/4/5 FIXED G17
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LT1083/LT1084/LT1085 Fixed
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BLOCK DIAGRA
VIN
+
–
THERMAL
LIMIT
VOUT
GND
LT1083/4/5 BD
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APPLICATIO S I FOR ATIO
The LT1083 family of three-terminal regulators are easy to
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.
These regulators offer lower dropout voltage and more
precise reference tolerance. Further, the reference stability 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.
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 charac-
teristics 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 capacitance 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
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-tooutput 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
resistance is a function of how fast the current limit is
1083ffd
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LT1083/LT1084/LT1085 Fixed
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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
does not cause any problems with the IC regulator and can
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
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.
Protection Diodes
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 operating 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 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.
D1
1N4002
(OPTIONAL)
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.
Load Regulation
VIN
IN
LT1083
ADJ
OUT
VOUT
+
COUT
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.
When power is first turned on, as the input voltage rises,
the output follows the input, allowing the regulator to start
Because the LT1083 is a three-terminal device, it is not
possible to provide true remote load sensing. Load regulation 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.
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,
1083ffd
8
LT1083/LT1084/LT1085 Fixed
U
W
U U
APPLICATIO S I FOR ATIO
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 ouput.
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,
θCASE-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 Commercial 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 Commercial 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
28V
INPUT
IN
+
OUTPUT
VIN
IN
GND
10,000μF
10k
LT1083-5 OUT
GND
VOUT = 5V
IOUT = 0A TO 15A
470Ω
MR1122
0.015Ω
1N914
28V
IN
LT1083-5 OUT
GND
1k
2 FEET #18 WIRE*
LT1083-5 OUT
1M
4N28
LT1083/4/5 TA04
LT1083/4/5 TA03
10k
+
*THE #18 WIRE ACTS
AS BALLAST RESISTANCE
INSURING CURRENT SHARING
BETWEEN BOTH DEVICES
LT1011
10k
–
28V
1N914
1083ffd
9
LT1083/LT1084/LT1085 Fixed
U
TYPICAL APPLICATIO S
7.5A Regulator
T1
TRIAD
F-269U
L
1MH
C30B
IN
20Ω
3
110VAC
20Ω
T2
1
1N4003
4
12V
0A TO 7.5A
LT1083-12 OUT
+ C1
GND
+
50,000μF
100μF
2
LT1004-1.2
C30B
1N4003
1N4003
1N914
16k*
1μF
82k
560Ω
15k
8
2
–15V
4
+
3
–
7
0.1μF
1
NC
1N4148
100pF
15V
8
–15V
4
7
* 1% FILM RESISTOR
L-DALE TO-5 TYPE
T2-STANCOR 11Z-2003
11k*
200k
LT1011
10k
16k*
15V
2N3904
–
3
1
8
LT1011
+
10k
2
6
+
1
2
4
–15V
15V
REGULATOR WITH SCR PREREGULATOR TO
LOWER POWER DISSIPATION. ABOUT 1.7V
DIFFERENTIAL IS MAINTAINED ACROSS THE
LT1083 INDEPENDENT OF LOAD CURRENT.
–
7
15k
3
LM301A
15V
11k*
LT1083/4/5 TA05
1μF
U
PACKAGE DESCRIPTIO
K Package
2-Lead TO-3 Metal Can
T Package
3-Lead Plastic TO-220
(LTC DWG # 05-08-1310)
(LTC DWG # 05-08-1420)
.760 – .775
(19.30 – 19.69)
.320 – .350
(8.13 – 8.89)
.060 – .135
(1.524 – 3.429)
.147 – .155
(3.734 – 3.937)
DIA
.390 – .415
(9.906 – 10.541)
.165 – .180
(4.191 – 4.572)
.045 – .055
(1.143 – 1.397)
.230 – .270
(5.842 – 6.858)
.420 – .480
(10.67 – 12.19)
.460 – .500
(11.684 – 12.700)
.038 – .043
(0.965 – 1.09)
.570 – .620
(14.478 – 15.748)
.330 – .370
(8.382 – 9.398)
.980 – 1.070
(24.892 – 27.178)
1.177 – 1.197
(29.90 – 30.40)
.655 – .675
(16.64 – 17.15)
.210 – .220
(5.33 – 5.59)
.151 – .161
(3.86 – 4.09)
DIA, 2PLCS
.167 – .177
(4.24 – 4.49)
R
.425 – .435
(10.80 – 11.05)
.067 – .077
(1.70 – 1.96)
.490 – .510
(12.45 – 12.95)
R
.520 – .570
(13.208 – 14.478)
.100
(2.540)
BSC
.218 – .252
(5.537 – 6.401)
.013 – .023
(0.330 – 0.584)
.028 – .038
(0.711 – 0.965)
.050
(1.270)
TYP
.095 – .115
(2.413 – 2.921)
T3 (TO-220) 0801
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)
.256
(6.502)
.060
(1.524)
TYP
.060
(1.524)
.390 – .415
(9.906 – 10.541)
.165 – .180
(4.191 – 4.572)
.045 – .055
(1.143 – 1.397)
15°
.060
(1.524)
.183
(4.648)
.330 – .370
(8.382 – 9.398)
+.008
.004 –.004
+0.203
0.102 –0.102
(
.059
(1.499)
)
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.300
(7.620)
+.012
.143 –.020
+0.305
3.632 –0.508
(
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
)
.050
(1.270)
.100
(2.54)
BSC
.050 ± .012
(1.270 ± 0.305)
.013 – .023
(0.330 – 0.584)
.420
.080
.420
.276
.325
.350
.205
.565
.565
.320
.090
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.090
.100
.070
.100
RECOMMENDED SOLDER PAD LAYOUT
M (DD3) 0204
.070
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
(14.224)
.325
(8.255)
.580
(14.732)
.700
(17.780)
.830 – .870
(21.08 – 22.10)
.580 – .6OO
(14.73 – 15.24)
.098
(2.489)
.124
(3.149)
.187 – .207
(4.75 – 5.26)
.620 – .64O
(15.75 – 16.26)
.275
(6.985)
MOUNTING HOLE
18° – 22°
.115 – .145
(2.92 – 3.68)
DIA
.060 – .080
(1.52 – 2.03)
.170 – .2OO
(4.32 – 5.08)
EJECTOR PIN MARKS
.105 – .125
(2.67 – 3.18)
DIA
3° – 7°
.170
(4.32)
MAX
.780 – .800
(19.81 – 20.32)
BOTTOM VIEW OF TO-3P
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
.042 – .052
(1.07 – 1.32)
.074 – .084
(1.88 – 2.13)
.215
(5.46)
BSC
.113 – .123
(2.87 – 3.12)
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
.087 – .102
(2.21 – 2.59)
.020 – .040
(0.51 – 1.02)
P3 0801
1083ffd
11
LT1083/LT1084/LT1085 Fixed
U
TYPICAL APPLICATIO S
Adjusting Output Voltage
VIN > 12V
Regulator with Reference
LT1085-5
VIN > 11.5V
5V to 10V
+
+
+
+
100μF
10μF
10V
LT1085-5
100μF
10μF
5VOUT
+
10μF*
LT1029
1k
LT1083/4/5 TA07
LT1083/4/5 TA06
*OPTIONAL IMPROVES RIPPLE REJECTION
Low Dropout Negative Supply
Battery Backed Up Regulated Supply
VIN
IN
VIN
+
LT1084-12 OUT
10μF
50Ω
GND
+
+
100μF
10,000μF
LT1083/4/5 TA08
FLOATING INPUT
5.2V LINE
5.0V BATTERY
LT1084-5
SELECT
FOR
CHARGE
RATE
VOUT = –12V
LT1084-5
6.5V
+
+
10μF
100μF
LT1083/4/5 TA09
RELATED PARTS
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
LT1374
4.5A, 500kHz Step-Down Converter
4.5A, 0.07Ω Internal Switch, SO-8 Package
LT1529
3A Low Dropout Regulator with 50μA IQ
500mV Dropout Voltage
LT1573
UltraFastTM Transient Response Low Dropout Regulator
Drives External PNP
LT1575
UltraFast Transient Response Low Dropout Regulator
Drives External N-Channel MOSFET
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
LT1584/85/87
7A/4.6A/3A Fast Response LDOs
Fast Transient Response for Microprocessor Applications
LT1735
Synchronous Step-Down Converter
High Efficiency, OPTI-LOOPTM Compensation
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
UltraFast and OPTI-LOOP are trademarks of Linear Technology Corporation.
1083ffd
12
Linear Technology Corporation
LT 1007 REV D • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1994
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