LT138A/LT338A
LM138/LM338
5A Positive Adjustable
Voltage Regulator
OBSOLETE:
FOR INFORMATION PURPOSES ONLY
Contact Linear Technology for Potential Replacement
Features
Description
Guaranteed 1% Initial Tolerance
nn Guaranteed 0.3% Load Regulation
nn Guaranteed 5A Output Current
nn 100% Thermal Limit Burn-In
nn 12A Transient Output Current
The LT®138A series of adjustable regulators provide 5A
output current over an output voltage range of 1.2V to
32V. The internal voltage reference is trimmed to less
than 1%, enabling a very tight output voltage. In addition
to excellent line and load regulation, with full overload
protection, the LT138A incorporates new current limiting circuitry allowing large transient load currents to be
handled for short periods. Transient load currents of up
to 12A can be supplied without limiting, eliminating the
need for a large output capacitor.
nn
Applications
High Power Linear Regulator
Battery Chargers
nn Power Driver
nn Constant-Current Regulator
nn
nn
The LT138A is an improved version of the popular LM138
with improved circuit design and advanced process techniques to provide superior performance and reliability.
The graph below shows the significant improvement in
output voltage tolerance achieved by using the LT138A
or LT338A.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
Parallel Regulators for Higher Current*
Output Voltage Error
12
VIN
VOUT
0.01Ω∗∗
5V
8A
ADJ
LT350A
VIN
VOUT
ADJ
0.016Ω**
121Ω
1%
11
OUTPUT VOLTAGE ERROR (%)
LT338A
VIN
10
9
2% RESISTORS
8
7
1% RESISTORS
6
LM338
LM338
LT338A
5
4
2% RESISTORS
3
LT338A
1% RESISTORS
2
1
365Ω
1%
0
138/338 TA01
*THIS CIRCUIT WILL NOT WORK WITH LM VERSION DEVICES
**CURRENT SHARING RESISTORS DEGRADE REGULATION TO 1%
1
10
OUTPUT VOLTAGE (V)
100
138A/338A TA02
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1
LT138A/LT339A
LM138/LM338
Absolute Maximum Ratings
(Note 1)
Power Dissipation............................... Internally Limited
Input-to-Output Voltage Differential.......................... 35V
Operating Junction Temperature Range
LT138A/LM138.................................. – 55°C to 150°C
LT338A/LM338..................................... 0°C to 125°C
Storage Temperature Range.................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................... 300°C
Preconditioning
100% Thermal Limit Burn-In
Pin Configuration
BOTTOM VIEW
VIN
FRONT VIEW
2
CASE
IS OUTPUT
1
3
VIN
2
VOUT
1
ADJ
ADJ (GND*)
K PACKAGE
2-LEAD TO-3 METAL CAN
TJMAX = 150°C, θJA = 35°C/W, θJA = 1°C/W (LT138A/LT138)
TJMAX = 125°C, θJA = 35°C/W, θJA = 1°C/W (LT338A/LT338)
OBSOLETE PACKAGE
2
P PACKAGE
3-LEAD PLASTIC TO-3P
TJMAX = 125°C, θJA = 45°C/W
OBSOLETE PACKAGE
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LT138A/LT338A
LM138/LM338
Electrical
Characteristics
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
LT138A
TYP
MAX
VREF
Reference Voltage
IOUT = 10mA, TJ = 25°C
1.238
1.250
1.262
1.225
1.250
1.270
0.005
0.02
3V ≤ (VIN – VOUT) ≤ 35V,
10mA ≤ IOUT ≤ 5A, P ≤ 50W
ΔVOUT
ΔVIN
Line Regulation
ΔVOUT
ΔVOUT
Load Regulation
l
3V ≤ (VIN – VOUT) ≤ 35V, (Note 3)
l
10mA ≤ IOUT ≤ 5A, (Note 3)
VOUT ≤ 5V
VOUT ≥ 5V
VOUT ≤ 5V
VOUT ≥ 5V
Thermal Regulation
20ms Pulse
Ripple Rejection
VOUT = 10V, f = 120Hz
CADJ = 0µF
CADJ = 10µF
l
l
l
l
60
MIN
LM138
TYP
MAX
UNITS
V
1.24
1.29
V
0.01
0.04
0.005
0.02
0.01
0.04
%/V
%/V
5
0.1
15
0.3
5
0.1
15
0.3
mV
%
20
0.3
30
0.6
20
0.3
30
0.6
mV
%
0.002
0.01
0.002
0.01
%/W
60
75
1.119
60
60
75
dB
dB
IADJ
Adjust Pin Current
l
45
100
45
100
µA
ΔIADJ
Adjust Pin Current Change
10mA ≤ IOUT ≤ 5A,
3V ≤ (VIN – VOUT) ≤ 35V
l
0.2
5
0.2
5
µA
Minimum Load Current
(VIN – VOUT) = 35V
l
3.5
5
3.5
5
mA
Current Limit
(VIN – VOUT) ≤ 10V
DC
0.5ms Peak
ISC
5
6
l
l
(VIN – VOUT) = 30V, TJ = 25ºC
ΔVOUT
ΔTemp
Temperature Stability
ΔVOUT
ΔTime
Long-Term Stability
en
RMS Output Noise (% of VOUT) 10HZ ≤ f ≤ 10kHz
θJC
Thermal Resistance
Junction-to-Case
l
TA = 125ºC, 1000 Hours
8
12
5
6
8
12
A
A
1
2
1
A
1
2
1
%
0.3
1
0.3
0.001
K Package
1
%
1
ºC/W
0.003
1
%
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
SYMBOL
PARAMETER
VREF
Reference Voltage
CONDITIONS
IOUT = 10mA
3V ≤ (VIN – VOUT) ≤ 35V,
10mA ≤ IOUT ≤ 5A, P ≤ 50W
ΔVOUT
ΔVIN
Line Regulation
ΔVOUT
ΔVOUT
Load Regulation
l
MIN
LT138A
TYP
MAX
1.238
1.250
1.262
1.225
1.250
1.270
0.005
0.02
3V ≤ (VIN – VOUT) ≤ 35V, (Note 3)
l
10mA ≤ IOUT ≤ 5A, (Note 3)
VOUT ≤ 5V
VOUT ≥ 5V
Thermal Regulation
VOUT ≤ 5V
VOUT ≥ 5V
l
l
20ms Pulse
MIN
LM138
TYP
MAX
1.19
1.24
1.29
V
0.01
0.04
0.005
0.02
0.03
0.06
%/V
%/V
5
0.1
15
0.3
5
0.1
25
0.5
mV
%
20
0.3
30
0.6
20
0.3
50
1
mV
%
0.002
0.02
0.002
0.02
%/W
UNITS
V
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3
LT138A/LT339A
LM138/LM338
electrical Characteristics
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.
SYMBOL
PARAMETER
CONDITIONS
Ripple Rejection
VOUT = 10V, f = 120Hz
CADJ = 0µF
CADJ = 10µF
IADJ
Adjust Pin Current
ΔIADJ
Adjust Pin Current Change
ISC
MIN
LT138A
TYP
60
60
75
l
l
MAX
MIN
LM138
TYP
60
60
75
MAX
UNITS
dB
dB
l
45
100
45
100
µA
10mA ≤ IOUT ≤ 5A,
3V ≤ (VIN – VOUT) ≤ 35V
l
0.2
5
0.2
5
µA
Minimum Load Current
(VIN – VOUT) = 35V
l
3.5
10
3.5
10
mA
Current Limit
(VIN – VOUT) ≤ 10V
DC
0.5ms Peak
5
6
l
l
8
12
(VIN – VOUT) = 30V, TJ = 25ºC
ΔVOUT
ΔTemp
Temperature Stability
ΔVOUT
ΔTime
Long-Term Stability
TA = 125ºC, 1000 Hours
en
RMS Output Noise (% of VOUT)
10Hz ≤ f ≤ 10kHz
θJC
Thermal Resistance
Junction-to-Case
K Package
l
5
6
8
12
A
A
1
2
1
A
1
2
1
%
0.3
1
0.3
0.001
1
%
0.003
1
%
1
ºC/W
Note 3: 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 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: Unless otherwise specified, these specifications apply: VIN – VOUT
= 5V and IOUT = 2.5A. These specifications are applicable for power
dissipations up to 50W.
Typical Performance Characteristics
Load Regulation
VIN = 15V
VOUT = 10V
PRELOAD = 50mA
0
IOUT = 3A
–0.1
IOUT = 5A
–0.2
–0.3
–0.4
–75 –50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
138/338 G01
4
Adjustment Current
65
ΔVOUT = 100mV
60
3
IOUT = 5A
IOUT = 3A
2
IOUT = 1A
ADJUSTMENT CURRENT (μA)
0.1
Dropout Voltage
4
INPUT-OUTPUT DIFFERENTIAL (V)
OUTPUT VOLTAGE DEVIATION (%)
0.2
55
50
45
40
35
1
–75 –50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
138/338 G02
30
–75
–25
25
75
TEMPERATURE (°C)
125
138A/338A G03
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LT138A/LT338A
LM138/LM338
Typical Performance Characteristics
Output Impedance
10
OUTPUT IMPEDANCE (Ω)
REFERENCE VOLTAGE (V)
1.260
1.250
1.240
Minimum Operating Current
5
VIN = 15V
VOUT = 10V
IOUT = 500mA
1
QUIESCENT CURRENT (mA)
Temperature Stability
1.270
CADJ = COUT = 0μF
0.1
0.01
CADJ = COUT = 10μF
0.001
1.230
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
0.0001
10
100
10k
1k
FREQUENCY (Hz)
100k
4
3
TJ = –55°C
2
1
0
1M
TJ = 150°C
TJ = 25°C
25 30 35
5
10 15 20
INPUT-OUTPUT DIFFERENTIAL (V)
0
138/338 G05
138A/338A G04
Ripple Rejection
138A/338A G06
Ripple Rejection
100
Ripple Rejection
80
100
CADJ = 10μF
CADJ = 10μF
80
CADJ = 0μF
60
40
VIN – VOUT = 5V
IOUT = 500mA
f = 120Hz
TJ = 25°C
20
0
0
5
60
CADJ = 0μF
40
20
20
15
10
25
OUTPUT VOLTAGE (V)
0
35
30
CADJ = 10μF
VIN = 15V
VOUT = 10V
IOUT = 0.2A
100
10
10k
1k
FREQUENCY (Hz)
138A/338A G07
8
PRELOAD = 1A
14
12
12
10
8
0
20
10
30
INPUT-OUTPUT DIFFERENTIAL (V)
40
138A/338A G10
PRELOAD = 5A
6
4
2
0
0.1
1
OUTPUT CURRENT (A)
VIN = 10V
VOUT = 5V
TCASE = 25°C
0
0.1
10
Current Limit
14
OUTPUT CURRENT (A)
PRELOAD = 5A
VIN = 15V
VOUT = 10V
f = 120Hz
TCASE = 25°C
138/338 G09
PRELOAD = 0A
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
PRELOAD = 0A
4
50
40
1M
CADJ = 0μF
60
Current Limit
PEAK CURRENT LIMIT
DC CURRENT LIMIT
TCASE = 25°C
12
100k
70
138A/338A G08
Current Limit
16
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
80
40
PRELOAD CURRENT = 0
TCASE = 25°C
10
VIN – VOUT = 10V
8
VIN – VOUT = 15V
6
VIN – VOUT = 20V
4
VIN – VOUT = 30V
2
1
10
100
0
0.1
1
10
100
TIME (ms)
TIME (ms)
138A/338A G11
138A/338A G12
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5
LT138A/LT339A
LM138/LM338
typical performance characteristics
Line Transient Response
0.5
VOUT = 10V
IOUT = 50mA
TJ = 25°C
0
OUTPUT VOLTAGE
DEVIATION (V)
1.0
Load Transient Response
3
CL = 1μF
CL = 10μF
–0.5
COUT = 0
CADJ = 0
–1.0
INPUT VOLTAGE
CHANGE (V)
1.0
0.5
0
10
0
20
TIME (μs)
40
30
2
1
CL = 1μF
CADJ = 10μF
CL = 0
CADJ = 0
0
–1
VIN = 15V
VOUT = 10V
TCASE = 25°C
PRELOAD = 100mA
–2
–3
–1.5
LOAD CURRENT (A)
OUTPUT VOLTAGE
DEVIATION (V)
1.5
6
4
2
0
0
10
20
TIME (μs)
30
40
138A/338A G14
138A/338A G13
Applications Information
General
The LT138A develops a 1.25V reference voltage between
the output and the adjustable terminal (see Figure 1). By
placing a resistor, R1, between these two terminals, a
constant current is caused to flow through R1 and down
through R2 to set the overall output voltage. Normally
this current is the specified minimum load current of 5mA
or 10mA. Because IADJ is very small and constant when
compared with the current through R1, it represents a small
error and can usually be ignored. It is easily seen from the
output voltage equation, that even if the resistors were of
exact value, the accuracy of the output is limited by the accuracy of VREF. Earlier adjustable regulators had a reference
tolerance of ± 4% which is dangerously close to the
±5% supply tolerance required in many logic and analog
systems. Further, even 1% resistors can drift 0.01%/°C,
adding additional error to the output voltage tolerance.
LT338A
VOUT
VIN
VIN
+
ADJ
VOUT
VREF
IADJ
50μA
R1
For example, using 2% resistors and ± 4% tolerance for
VREF, calculations will show that the expected range of a
5V regulator design would be 4.66V ≤ VOUT ≤ 5.36V or
approximately ±7%. If the same example were used for a
15V regulator, the expected tolerance would be ±8%. With
these results most applications required some method of
trimming, usually a trim pot. This solution is both expensive
and not conductive to volume production.
One of the enhancements of Linear Technology’s adjustable regulators over existing devices is the tightened initial
tolerance of VREF . This allows relatively inexpensive 1%
or 2% film resistors to be used for R1 and R2 to set the
output voltage within an acceptable tolerance.
With a guaranteed 1% reference, a 5V power supply
design, using ± 2% resistors, would have a worst-case
manufacturing tolerance of ±4%. If 1% resistors are used,
the tolerance will drop to ±2.5%. A plot of the worst-case
output voltage tolerance as a function of resistor tolerance
is shown on the front page of this data sheet.
For convenience, a table of standard 1% resistor values
is shown in Table 1.
R2
( )
VOUT = VREF 1 + R2 + IADJ • R2
R1
138A/338A F01
Figure 1. Basic Adjustable Regulator
6
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LT138A/LT338A
LM138/LM338
applications information
Table 1. 0.5% and 1% Standard Resistance Values
1.00
1.47
2.15
3.16
4.64
6.81
1.02
1.50
2.21
3.24
4.75
6.98
1.05
1.54
2.26
3.32
4.87
7.15
1.07
1.58
2.32
3.40
4.99
7.32
1.10
1.62
2.37
3.48
5.11
7.50
1.13
1.65
2.43
3.57
5.23
7.68
1.15
1.69
2.49
3.65
5.36
7.87
1.18
1.74
2.55
3.74
5.49
8.06
1.21
1.78
2.61
3.83
5.62
8.25
1.24
1.82
2.67
3.92
5.76
8.45
1.27
1.87
2.74
4.02
5.90
8.66
1.30
1.91
2.80
4.12
6.04
8.87
1.33
1.96
2.87
4.22
6.19
9.09
1.37
2.00
2.94
4.32
6.34
9.31
1.40
2.05
3.01
4.42
6.49
9.53
1.43
2.10
3.09
4.53
6.65
9.76
Standard resistance values are obtained from the Decade Table by
multiplying by multiples of 10. As an example, 1.21 can represent 1.21Ω,
12.1Ω, 121Ω, 1.21k etc.
Bypass Capacitors
Input bypassing using a 1µF tantalum or 25µF electrolytic
is recommended when the input filter capacitors are more
than 5 inches from the device. Improved ripple rejection
(80dB) can be accomplished by adding a 10µF capacitor
from the ADJ pin to ground. Increasing the size of the
capacitor to 20µF will help ripple rejection at low output
voltage since the reactance of this capacitor should be
small compared to the voltage setting resistor, R2. For
improved AC transient response and to prevent the possibility of oscillation due to unknown reactive load, a 1µF
capacitor is also recommended at the output. Because of
their low impedance at high frequencies, the best type of
capacitor to use is solid tantalum.
Protection Diodes
The LT138A/LT338A do not require a protection diode
from the adjustment terminal to the output (see Figure 2).
Improved internal circuitry eliminates the need for this
diode when the adjustment pin is bypassed with a capacitor to improve ripple rejection.
If a very large output capacitor is used, such as a 100µF
shown in Figure 2, the regulator could be damaged or
destroyed if the input is accidentally shorted to ground
or crowbarred, due to the output capacitor discharging
into the output terminal of the regulator. To prevent this, a
diode D1 as shown, is recommended to safely discharge
the capacitor.
D1
1N4002
LT338A
VIN
VIN
VOUT
ADJ
VOUT
R1
CADJ
10μF
R2
NOT
NEEDED
+
COUT
100μF
138A/338A F02
Figure 2
Load Regulation
Because the LT138A is a three-terminal device, it is not
possible to provide true remote load sensing. Load regulation will be limited by the resistance of the wire connecting
the regulator to the load. The data sheet specification for
load regulation is measured at the bottom of the package.
Negative side sensing is a true Kelvin connection, with the
bottom of the output divider returned to the negative side
of the load. Although it may not be immediately obvious,
best load regulation is obtained when the top of the resistor divider, R1, is connected directly to the case not to the
load. This is illustrated in Figure 3. If R1 were connected
to the load, the effective resistance between the regulator
and the load would be:
⎛ R2+R1⎞
RP ⎜
⎟,RP = Parasitic Line Resistance
⎝ R1 ⎠
Connected as shown, RP is not multiplied by the divider
ratio. RP is about 0.004Ω per foot using 16 gauge wire. This
translates to 4mV/ft at 1A load current, so it is important
to keep the positive lead between regulator and load as
short as possible, and use large wire or PC board traces.
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7
LT138A/LT339A
LM138/LM338
applications information
RP
PARASITIC
LINE RESISTANCE
LT338A
VIN
VIN
VOUT
ADJ
CONNECT
R1 TO CASE
R1
RL
R2
CONNECT
R2 TO LOAD
138A/338A F03
Figure 3. Connections for Best Load Regulation
Typical Applications
Improving Ripple Rejection
LT338A
VIN
+
VOUT
VIN
1μF
5V
R1
121Ω
1%
ADJ
R2
365Ω
1%
+
CL*
10μF
138A/338A TA03
*C1 IMPROVES RIPPLE REJECTION, XC
SHOULD BE SMALL COMPARED TO R2
1.2V to 25V Adjustable Regulator
LT338A
R1
240Ω
ADJ
+
VOUT†
VOUT
VIN
VIN
C1*
1μF
R2
5k
+
C2**
1μF
138A/338A TA04
*NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS
**OPTIONAL, IMPROVES TRANSIENT RESPONSE
( )
VOUT = 1.25V 1 + R2
R1
†
8
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LT138A/LT338A
LM138/LM338
typical Applications
5V Regulator with Shutdown
LT338A
VIN
VOUT
VIN
+
5V
121Ω
1%
ADJ
1μF
1k
TTL
2N3904
365Ω
1%
1k
138A/338A TA05
Temperature Compensated Lead Acid Battery Charger
LT338A
3A
VOUT
VIN
243Ω
1%
ADJ
10k
50Ω
2N3906
12V
2k
50k
138A/338A TA07
Remote Sensing
RP
(MAX DROP
300mV)
LT338A
VOUT
VIN
ADJ
VOUT
5V
VIN
7
1
8
365Ω
2
LM301A
+
121Ω
6
–
25Ω
100pF
4
RL
1k
3
5μF
+
VIN
25Ω
RETURN
RETURN
138A/338A TA06
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9
10
Q2
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160k
Q1
Q3
30k
180Ω
Q5
Q7
130Ω
4k
Q6
310Ω
Q8
4.1k
Q11
12.4k
Q9
190Ω
4.1k
Q10
10Ω
Q12 Q13
Q1
50Ω
Q14
5.1k
Q16
3k
Q15
+
5.6k
C2
30pF
+
C1
30pF
20k
Q17
Q18
ADJ
12k
Q19
2.4k
Q20
1.6k
Q21
Q22
6.7k
Q23
16k
Q25
C3
5pF
Q24
400Ω
12k
120Ω
Q26 200Ω
300Ω
160k
Q27
VOUT
160Ω
D2
18k
D1
138A/338A SS
0.01Ω
3Ω
Q28
Schematic Diagram
Q4
310Ω
VIN
LT138A/LT339A
LM138/LM338
LT138A/LT338A
138afd
LT138A/LT338A
LM138/LM338
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
K Package
2-Lead TO-3 Metal Can
(Reference LTC DWG # 05-08-1310)
0.760 – 0.775
(19.30 – 19.69)
0.320 – 0.350
(8.13 – 8.89)
0.060 – 0.135
(1.524 – 3.429)
0.420 – 0.480
(10.67 – 12.19)
0.038 – 0.043
(0.965 – 1.09)
1.177 – 1.197
(29.90 – 30.40)
0.655 – 0.675
(16.64 – 17.15)
0.210 – 0.220
(5.33 – 5.59)
0.425 – 0.435
(10.80 – 11.05)
0.151 – 0.161
(3.86 – 4.09)
DIA, 2PLCS
0.167 – 0.177
(4.24 – 4.49)
R
0.067 – 0.077
(1.70 – 1.96)
0.490 – 0.510
(12.45 – 12.95)
R
K2 (TO-3) 1098
OBSOLETE PACKAGE
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For more information www.linear.com/LT138A
11
LT138A/LT339A
LM138/LM338
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
P Package
3-Lead Plastic TO-3P (Similar to TO-247)
(Reference LTC DWG # 05-08-1450)
.560
(14.224)
.325
(8.255)
.580
(14.732)
.700
(17.780)
.098
(2.489)
.124
(3.149)
.187 – .207
(4.75 – 5.26)
.620 – .64O
(15.75 – 16.26)
.275
(6.985)
.830 – .870
(21.08 – 22.10)
.580 – .6OO
(14.73 – 15.24)
MOUNTING HOLE
.115 – .145
(2.92 – 3.68)
DIA
18 – 22
.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)
.087 – .102
(2.21 – 2.59)
.020 – .040
(0.51 – 1.02)
P3 0801
OBSOLETE PACKAGE
12
138afd
For more information www.linear.com/LT138A
LT138A/LT338A
LM138/LM338
Revision History
(Revision history begins at Rev D)
REV
DATE
DESCRIPTION
D
05/15
Obsolete packaged parts.
PAGE NUMBER
1, 2, 12
138afd
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.
For more
information
www.linear.com/LT138A
13
LT138A/LT339A
LM138/LM338
Typical Application
Lamp Flasher
Automatic Light Control
LT338A
15V
+
ADJ
1μF
LT338A
VOUT
VIN
ADJ
+
10μF
12k
10μF
+
1k
12k
1.2k
12V
+
OFF
VOUT
VIN
10μF
2N3904
138A/338A TA09
12k
138A/338A TA08
Protected High Current Lamp Driver
15V
12V
5A
LT338A
VIN
VOUT
ADJ
TTL OR
CMOS
10k
138A/338A TA10
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LT1083/LT1084/
LT1085
3A/5A/7.5A Low Dropout Regulators
Fixed Outputs, VIN Up to 30V
LT1580
7A Fast Transient Response Regulator with 0.7V Dropout
For 3.3V to 2.xxV Applications
LT1581
10A Fast Transient Response Regulator
For 3.3V to 2.xxV Applications
LT1584/LT1585/
LT1587
7A/4.6A/3A Low Dropout Fast Transient Response Regulator
For 1.2V to 3.3V Outputs from 5V
LT1764
3A Fast Transient Response Regulator
Dropout Voltage 340mV, Low Noise: 40µVRMS
14 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LT138A
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LT138A
138afd
LT 0515 REV D • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 1991