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LM338K

Part # LM338K
Description IC REG LDO ADJ 5A TO3
Category TRANSISTOR
Availability Out of Stock
Qty 0
Qty Price
1 + $13.78920

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Technical Document


DISCLAIMER: The information provided herein is solely for informational purposes. Customers must be aware of the suitability of this product for their application, and consider that variable factors such as Manufacturer, Product Category, Date Codes, Pictures and Descriptions may differ from available inventory.

LM138/238
LM338
March 1993
ADJUSTABLE VOLTAGE REGULATORS
THREE-TERMINAL 5-A
.GUARANTEED 7A PEAK OUTPUT CURRENT
.GUARANTEED 5A OUTPUT CURRENT
.ADJUSTABLE OUTPUT DOWN TO 1.2V
.LINE REGULATION TYPICALLY 0.005% /V
.LOAD REGULATION TYPICALLY 0.1%
.GUARANTEED THERMAL REGULATION
.CURRENT LIMIT CONSTANT WITH TEM-
PERATURE
.STANDARD 3-LEAD TRANSISTOR PACKAGE
DESCRIPTION
The LM138/LM238/LM338 are adjustable 3-terminal
positive voltage regulators capable of supplying inex-
cess of 5A over a 1.2V to 32V output range. They are
exceptionally easy to use and require only 2 resistors
toset the output voltage. Careful circuitdesign has re-
sulted in outstanding load and line regulation com-
parable to many commercial power supplies. The
LM138 family is supplied in a standard 3-lead transis-
torpackage.
A unique featureof the LM138 family is time-de-
pendent current limiting. The current limit circuitry
allowspeak currents of upto 12A tobedrawn fromthe
regulator for short periods of time. This allows the
LM138 to be used with heavy transient loads and
speedsstart-up under full-load conditions. Under sus-
tained loading conditions, the current limit decreases
to a safe value protecting the regulator. Also included
on the chip are thermal overload protection and safe
areaprotection forthepower transistor. Overloadpro-
tection remains functional even if the adjustment pin
is accidentally disconnected.
Normally,nocapacitors are needed unless thedevice
is situated far from the input filter capacitors in which
case an input bypass is needed. An optional output
capacitor can be added to improve transient res-
ponse. The adjustment terminal can be bypassed to
achieve very high ripple rejection ratios which are dif-
ficult to achieve with standard 3-terminal regulators.
Besidesreplacing fixedregulatorsordiscretedesigns,
the LM238 is useful in a wide variety of other applica-
tions. Since the regulator is ”floating” and sees only
theinput-to-output differential voltage,suppliesofsev-
eral hundred volts can be regulated as long as the
maximum input to input differential is not exceeded.
The LM138/LM238/LM338 are packaged in standard
steel TO-3 transistor packages. The LM138 is rated
foroperation from -55
o
Cto150
o
C, the LM238 from
–25°C to + 150°C and the LM338 from 0°Cto+
125°C.
TO3
K SUFFIX
(Steel Can)
ORDER CODE
PART
NUMBER
TEMPERATURE
RANGE
PACKAGE
K
LM138
LM238
LM338
-55
o
C to + 150
o
C
-25
o
C to + 150
o
C
0
o
C to + 125
o
C
•
•
•
EXAMPLE: LM138K
PIN CONNECTION
(bottom view)
Case is output
1/12
ABSOLUTE MAXIMUM RATING
Symbol Parameter Value Unit
P
tot
Power Dissipation Internally Limited W
V
I
-V
O
Input-Output Voltage DIfferential 35 V
T
oper
Operating Junction Temperature Range LM138
LM238
LM338
-55 to 150
-25 to 150
0 to 125
o
C
T
stg
Storage Temperature Range -65 to 150
o
C
T
lead
Lead Temperature (Soldering, 10 seconds) 300
o
C
THERMAL CHARACTERISTICS
Symbol Parameter Value Unit
R
th(j-c)
Typical Junction-Case Thermal Resistance 1.4
o
C/W
R
th(j-a)
Max Junction-Ambient Thermal Resistance 35
o
C/W
SCHEMATIC DIAGRAM
LM138-LM238-LM338
2/12
ELECTRICAL CHARACTERISTICS
LM138: -55 ≤ T
j
≤ 150
o
C, V
I
-V
O
= 5V, I
O
=2.5A
LM238: -25 ≤ T
j
≤ 150
o
C, V
I
-V
O
= 5V, I
O
=2.5A
LM338: 0 ≤ T
j
≤ 150
o
C, V
I
-V
O
= 5V, I
O
= 2.5A
Although power dissipation is internally limited, these specifications apply to power dissipation up to
50W (unless otherwise specified).
Symbol Parameter LM138-LM238 LM338 Unit
Min. Typ. Max. Min. Typ. Max.
K
VI
Line Regulation - (note 1)
T
amb
=25
o
C, 3 V ≤ (V
I
-V
O
)≤35 V
0.005 0.01 0.005 0.03 %/V
K
VO
Load Regulation T
amb
=25
o
C, 10 mA ≤ I
O
≤ 5A
V
O
≤5V - (note 1)
V
O
≥ 5V - (note 1)
5
0.1
15
0.3
5
0.1
25
0.5
mV
%
Thermal Regulation (pulse = 20 ms) 0.002 0.01 0.002 0.02 %/W
I
adj
Adjustment Pin Current 45 100 45 100 µA
∆I
adj
Adjustment Pin Current Change
10 mA ≤ I
L
≤ 5A,3V≤(V
I
-V
O
)≤35 V
0.2 5 0.2 5 µA
v
(ref)
Reference Voltage
3V ≤ (V
I
-V
O
)≤35 V, 10 mA ≤ I
O
≤ 5A, P ≤ 50W
1.19 1.24 1.29 1.19 1.24 1.29 V
K
VI
Line Regulation - (note 1)
3V≤(V
I
-V
O
)≤35 V
0.02 0.04 0.02 0.06 %/V
K
VO
Load Regulation 10 mA ≤ I
O
≤ 5A
V
O
≤5V - (note 1)
V
O
≥ 5V - (note 1)
20
0.3
30
0.6
20
0.3
50
1
mV
%
K
VT
Temperature Stability (T
min
≤ T
j
≤ T
max
)11%
I
O(min)
Minimum Load Current (V
I
-V
O
≤35 V) 3.5 5 3.5 10 mA
I
O(max)
Current Limit (V
I
-V
O
≤10 V)
DC
0.5 ms Peak
V
I
-V
O
=30V
5
7
8
12
1
5
7
8
12
1
A
RMS Output Noise, % of V
O
(T
amb
=25
o
C, 10 Hz ≤ f ≤ 10 KHz)
0.003 0.003 %
R
vf
Ripple Rejection Ratio
V
O
= 10 V, f = 120 Hz
C
adi
=10µF60
60
75 60
60
75
dB
K
VH
Long Term Stability (T
amb
= 125
o
C) 0.3 1 0.3 1 %
Note 1 : Regulation is measured at constant junction temperature. Changes in output voltage due to heating effects are taken
into account separately by thermal rejection.
LM138-LM238-LM338
3/12
1234NEXT
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