Original Creation Date: 07/12/95
Last Update Date: 08/13/01
Last Major Revision Date: 08/02/01
MNLM138-X REV 1A0 MICROCIRCUIT DATA SHEET
5 AMP ADJUSTABLE POWER REGULATOR
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 current 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 transient loads and speeds
start-up under full-load condition. Under sustained loading conditions, the current limit
decreases to a safe value protecting the regulator. Also included 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.
Normanlly, no capacitors are needed unless the device is situated 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 bypassing the adjustment pin will
increase the regulator's ripple rejection.
Besides replacing fixed regulators or discrete designs, the LM 138 is usefull 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 voltage, is not exceeded.
NS Part Numbers
LM138K-MIL
Industry Part Number
LM138
Prime Die
LM138
Processing
MIL-STD-883, Method 5004
Quality Conformance Inspection
MIL-STD-883, Method 5005
Subgrp Description Temp ( C)
o
1 Static tests at +25
2 Static tests at +125
3 Static tests at -55
4 Dynamic tests at +25
5 Dynamic tests at +125
6 Dynamic tests at -55
7 Functional tests at +25
8A Functional tests at +125
8B Functional tests at -55
9 Switching tests at +25
10 Switching tests at +125
11 Switching tests at -55
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MICROCIRCUIT DATA SHEET
MNLM138-X REV 1A0
(Absolute Maximum Ratings)
(Note 1)
Power Dissipation Internally limited
Storage Temperature -65 C to +150 C
Lead Temperature 300 C(Soldering, 10 Sec.)
Maximum Juction Temperature 150 C
Input/Output Differential +40V, -0.3V
Thermal Resistance
ThetaJA 40 CStill Air TBD500LF/Min Air Flow
TBDThetaJC
Package Weight
(Typical) TBD
ESD Tolerance
(Note 3) TBD
Note 1: Absolute Maximum Rating indicate limits beyond which damage to the device may occur.
Operating Ratings indicate conditions for which the device is functional, but do not
guarantee specific performance limits. For guaranteed specifications and test
conditions, see the Electrical Characteristics. The guaranteed specifications apply
only for the test conditions listed. Some performance characteristics may degrade
when the device is not operated under the listed test condtions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and is
dictated by Tjmax (maximum junction temperature), ThetaJA (package junction to
ambient thermal resistance), and TA (ambient temperature). The maximum allowable
power dissipation at any temperature is Pdmax = (Tjmax - TA)/ThetaJA or the number
given in the Absolute Maximum Ratings, whichever is lower.
Note 3: Human body model, 1.5K ohms in series with 100pF
2
MNLM138-X REV 1A0 MICROCIRCUIT DATA SHEET
Electrical Characteristics
DC PARAMETERS
(The following conditions apply to all the following parameters, unless otherwise specified.)
DC: Vdiff=5V, Il=10mA
SYMBOL PARAMETER CONDITIONS NOTES PIN-
NAME MIN MAX UNIT SUB-
GROUPS
Rline Line Regulation 3V < Vdiff < 35V -3.5 3.5 mV 1
3.3V < Vdiff < 35V -14 14 mV 2, 3
Rload Load Regulation Vdiff=3V, 10mA < Il < 5A, Vout=Vref -3.8 3.8 mV 1
Vdiff=3.3V, 10mA < Il < 5A, Vout=Vref -8 8 mV 2, 3
Vdiff=35V, 10mA < Il < 150mA,
Vout=Vref -3.8 3.8 mV 1
-8 8 mV 2, 3
Vrth Thermal
Regulation Vdiff=10V, Pulse=20mS, Il=1A 1 0.01 %/Wat
t
1
Iadj Adjustment Pin
Current Vdiff=3V 2 2 100 uA 1, 2,
3
Vdiff=35V 2 100 uA 1, 2,
3
Delta Iadj Adjustment Pin
Current Change 3V<Vdiff<35V 2 -5 5 uA 1, 2,
3
10mA<Il<5A -5 5 uA 1, 2,
3
Ilmin Min Load Current Vdiff=3V, Vout=1.4V 2 0.5 5 mA 1, 2,
3
Vdiff=35V, Vout=1.4V 0.5 5 mA 1, 2,
3
Vref Reference Voltage Vdiff=3V 2 1.19 1.29 V 1, 2,
3
Vdiff=3V, Il=5A 1.19 1.29 V 1, 2,
3
Vdiff=5V, Il=7A 1.19 1.29 V 1, 2,
3
Vdiff=35V 1.19 1.29 V 1, 2,
3
Vdiff=35V, Il=150mA 1.19 1.29 V 1, 2,
3
Icl Current Limit Vdiff=10V, T=0.5mS, Vout=0V 7 16 A 1, 2,
3
T=5.0mS, Vout=0V 5 15 A 1, 2,
3
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MNLM138-X REV 1A0 MICROCIRCUIT DATA SHEET
Electrical Characteristics
AC PARAMETERS
(The following conditions apply to all the following parameters, unless otherwise specified.)
DC: Vdiff=5V, Il=10mA
SYMBOL PARAMETER CONDITIONS NOTES PIN-
NAME MIN MAX UNIT SUB-
GROUPS
Rr Ripple Rejection
Ratio Vout=Vref, ein=1Vrms, f=120Hz,
Il=500mA 360 dB4
Note 1: Datalog reading in mV, 0.01 % = 1.19mV.
Note 2: Vdiff = 3.3V at 125 C and -55 C.
Note 3: Family Board not required for this device.
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MICROCIRCUIT DATA SHEET
MNLM138-X REV 1A0
Graphics and Diagrams
GRAPHICS# DESCRIPTION
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See attached graphics following this page.
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