Adjustable Regulators. LM338 Datasheet

LM338 Regulators. Datasheet pdf. Equivalent


National Semiconductor LM338
May 1998
LM138/LM338
5-Amp Adjustable Regulators
General Description
The LM138 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 5A over a
1.2V to 32V output range. They are exceptionally easy to
use and require only 2 resistors to set the output voltage.
Careful circuit design has resulted in outstanding load and
line regulation — comparable to many commercial power
supplies. The LM138 family is supplied in a standard 3-lead
transistor package.
A unique feature of the LM138 family is time-dependent cur-
rent limiting. The current limit circuitry allows peak currents
of up to 12A to be drawn from the regulator for short periods
of time. This allows the LM138 to be used with heavy tran-
sient loads and speeds start-up under full-load conditions.
Under sustained loading conditions, the current limit de-
creases to a safe value protecting the regulator. Also in-
cluded on the chip are thermal overload protection and safe
area protection for the power transistor. Overload protection
remains functional even if the adjustment pin is accidentally
disconnected.
Normally, no capacitors are needed unless the device is situ-
ated more than 6 inches from the input filter capacitors in
which case an input bypass is needed. An output capacitor
can be added to improve transient response, while bypass-
ing the adjustment pin will increase the regulator’s ripple re-
jection.
Besides replacing fixed regulators or discrete designs, the
LM138 is useful in a wide variety of other applications. Since
the regulator is “floating” and sees only the input-to-output
differential voltage, supplies of several hundred volts can be
regulated as long as the maximum input to output differential
is not exceeded, i.e., do not short-circuit output to ground.
The part numbers in the LM138 series which have a K suffix
are packaged in a standard Steel TO-3 package, while those
with a T suffix are packaged in a TO-220 plastic package.
The LM138 is rated for −55˚C TJ +150˚C, and the LM338
is rated for 0˚C TJ +125˚C.
Features
n Guaranteed 7A peak output current
n Guaranteed 5A output current
n Adjustable output down to 1.2V
n Guaranteed thermal regulation
n Current limit constant with temperature
n P+ Product Enhancement tested
n Output is short-circuit protected
Applications
n Adjustable power supplies
n Constant current regulators
n Battery chargers
Connection Diagrams (See Physical Dimension section for further information)
(TO-3 STEEL)
Metal Can Package
(TO-220)
Plastic Package
DS009060-30
Bottom View
Order Number LM138K STEEL or LM338K STEEL
See NS Package Number K02A
DS009060-31
Front View
Order Number LM338T
See NS Package Number T03B
© 1999 National Semiconductor Corporation DS009060
www.national.com


LM338 Datasheet
Recommendation LM338 Datasheet
Part LM338
Description 5-Amp Adjustable Regulators
Feature LM338; LM138/LM338 5-Amp Adjustable Regulators May 1998 LM138/LM338 5-Amp Adjustable Regulators General .
Manufacture National Semiconductor
Datasheet
Download LM338 Datasheet




National Semiconductor LM338
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
(Note 4)
Power Dissipation
Input/Output Voltage Differential
Storage Temperature
Internally limited
+40V, −0.3V
−65˚C to +150˚C
Lead Temperature
Metal Package (Soldering, 10 seconds)
Plastic Package (Soldering, 4 seconds)
ESD Tolerance
300˚C
260˚C
TBD
Operating Temperature Range
LM138
LM338
−55˚C TJ +150˚C
0˚C TJ +125˚C
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, VIN − VOUT = 5V; and IOUT = 10 mA. (Note 2)
Symbol
Parameter
Conditions
LM138
Units
Min Typ Max
VREF
VRLINE
Reference Voltage
Line Regulation
3V (VIN − VOUT) 35V,
10 mA IOUT 5A, P 50W
3V (VIN − VOUT) 35V (Note 3)
1.19 1.24 1.29
V
0.005
0.02
0.01
0.04
%/V
%/V
VRLOAD
Load Regulation
10 mA IOUT 5A (Note 3)
0.1 0.3
0.3 0.6
%
%
Thermal Regulation
20 ms Pulse
0.002 0.01 %/W
IADJ
IADJ
Adjustment Pin Current
Adjustment Pin Current Change
VR/T
ILOAD(Min)
ICL
Temperature Stability
Minimum Load Current
Current Limit
10 mA IOUT 5A,
3V (VIN − VOUT) 35V
TMIN TJ TMAX
VIN − VOUT = 35V
VIN − VOUT 10V
DC
45 100 µA
0.2 5 µA
1%
3.5 5 mA
58
A
0.5 ms Peak
7 12
A
VIN − VOUT = 30V
11A
VN
RMS Output Noise, % of VOUT
10 Hz f 10 kHz
0.003
%
Ripple Rejection Ratio
VOUT = 10V, f = 120 Hz, CADJ = 0 µF
60
dB
VOUT = 10V, f = 120 Hz, CADJ = 10 µF
60
75
dB
Long-Term Stability
TJ = 125˚C, 1000 Hrs
0.3 1
%
θJC Thermal Resistance,
K Package
1 ˚C/W
Junction to Case
θJA
Thermal Resistance, Junction to
K Package
Ambient (No Heat Sink)
35 ˚C/W
Electrical Characteristics
Symbol
Parameter
VREF
VRLINE
VRLOAD
IADJ
IADJ
Reference Voltage
Line Regulation
Load Regulation
Thermal Regulation
Adjustment Pin Current
Adjustment Pin Current Change
www.national.com
Conditions
3V (VIN − VOUT) 35V,
10 mA IOUT 5A, P 50W
3V (VIN − VOUT) 35V (Note 3)
10 mA IOUT 5A (Note 3)
20 ms Pulse
10 mA IOUT 5A,
3V (VIN − VOUT) 35V
2
LM338
Min Typ Max
1.19 1.24 1.29
Units
V
0.005 0.03 %/V
0.02 0.06 %/V
0.1 0.5
%
0.3 1
%
0.002 0.02 %/W
45 100 µA
0.2 5 µA



National Semiconductor LM338
Electrical Characteristics (Continued)
Symbol
Parameter
VR/T
ILOAD(Min)
ICL
Temperature Stability
Minimum Load Current
Current Limit
VN RMS Output Noise, % of VOUT
Ripple Rejection Ratio
Long-Term Stability
θJC Thermal Resistance
Junction to Case
θJA Thermal Resistance, Junction to
Ambient (No Heat Sink)
Conditions
TMIN TJ TMAX
VIN − VOUT = 35V
VIN − VOUT 10V
DC
0.5 ms Peak
VIN − VOUT = 30V
10 Hz f 10 kHz
VOUT = 10V, f = 120 Hz, CADJ = 0 µF
VOUT = 10V, f = 120 Hz, CADJ = 10 µF
TJ = 125˚C, 1000 hrs
K Package
T Package
K Package
T Package
LM338
Units
Min Typ Max
1%
3.5 10 mA
58
A
7 12
A
1A
0.003
%
60 dB
60 75
dB
0.3 1
%
1 ˚C/W
4 ˚C/W
35 ˚C/W
50 ˚C/W
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: These specifications are applicable for power dissipations up to 50W for the TO-3 (K) package and 25W for the TO-220 (T) package. Power dissipation is
guaranteed at these values up to 15V input-output differential. Above 15V differential, power dissipation will be limited by internal protection circuitry. All limits (i.e.,
the numbers in the Min. and Max. columns) are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 3: Regulation is measured at a constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specifications for thermal regulation.
Note 4: Refer to RETS138K drawing for military specifications of LM138K.
Typical Performance Characteristics
Current Limit
Current Limit
Current Limit
Load Regulation
DS009060-32
Dropout Voltage
DS009060-33
Adjustment
Current
DS009060-34
DS009060-35
DS009060-36
3
DS009060-37
www.national.com







@ 2014 :: Datasheetspdf.com :: Semiconductors datasheet search & download site (Privacy Policy & Contact)