LM150,LM350,LM350A
LM150/LM350A/LM350 3-Amp Adjustable Regulators
Literature Number: SNVS772A
LM150/LM350A/LM350
3-Amp Adjustable Regulators
General Description
The LM150 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 3A over a
1.2V to 33V output range. They are exceptionally easy to
use and require only 2 external resistors to set the output
voltage. Further, both line and load regulation are compa-
rable to discrete designs. Also, the LM150 is packaged in
standard transistor packages which are easily mounted and
handled.
In addition to higher performance than fixed regulators, the
LM150 series offers full overload protection available only in
IC’s. Included on the chip are current limit, thermal overload
protection and safe area protection. All overload protection
circuitry remains fully functional even if the adjustment ter-
minal is accidentally disconnected.
Normally, 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 bypass-
ing the adjustment pin will increase the regulator’s ripple
rejection.
Besides replacing fixed regulators or discrete designs, the
LM150 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., avoid short-circuiting the output.
By connecting a fixed resistor between the adjustment pin
and output, the LM150 can be used as a precision current
regulator. Supplies with electronic shutdown can be
achieved by clamping the adjustment terminal to ground
which programs the output to 1.2V where most loads draw
little current.
The part numbers in the LM150 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 LM150 is rated for −55˚C ≤T
J
≤+150˚C, while the
LM350A is rated for −40˚C ≤T
J
≤+125˚C, and the LM350 is
rated for 0˚C ≤T
J
≤+125˚C.
Features
nAdjustable output down to 1.2V
nGuaranteed 3A output current
nGuaranteed thermal regulation
nOutput is short circuit protected
nCurrent limit constant with temperature
nP
+
Product Enhancement tested
n86 dB ripple rejection
nGuaranteed 1% output voltage tolerance (LM350A)
nGuaranteed max. 0.01%/V line regulation (LM350A)
nGuaranteed max. 0.3% load regulation (LM350A)
Applications
nAdjustable power supplies
nConstant current regulators
nBattery chargers
Connection Diagrams
(TO-3 STEEL)
Metal Can Package
(TO-220)
Plastic Package
00906104
Case is Output
Bottom View
Order Number LM150K STEEL
or LM350K STEEL
See NS Package Number K02A
Order Number LM150K/883
See NS Package Number K02C
00906105
Front View
Order Number LM350AT or LM350T
See NS Package Number T03B
May 1998
LM150/LM350A/LM350 3-Amp Adjustable Regulators
© 2004 National Semiconductor Corporation DS009061 www.national.com
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 Internally Limited
Input-Output Voltage Differential +35V
Storage Temperature −65˚C to +150˚C
Lead Temperature
Metal Package (Soldering, 10
sec.)
Plastic Package (Soldering, 4
sec.)
300˚C
260˚C
ESD Tolerance TBD
Operating Temperature Range
LM150 −55˚C ≤T
J
≤+150˚C
LM350A −40˚C ≤T
J
≤+125˚C
LM350 0˚C ≤T
J
≤+125˚C
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Temperature
Range. Unless otherwise specified, V
IN
−V
OUT
= 5V, and I
OUT
= 10 mA. (Note 2)
Parameter Conditions LM150 Units
Min Typ Max
Reference Voltage 3V ≤(V
IN
−V
OUT
)≤35V, 1.20 1.25 1.30 V
10 mA ≤I
OUT
≤3A, P ≤30W
Line Regulation 3V ≤(V
IN
−V
OUT
)≤35V (Note 3) 0.005 0.01 %/V
0.02 0.05 %/V
Load Regulation 10 mA ≤I
OUT
≤3A (Note 3) 0.1 0.3 %
0.3 1 %
Thermal Regulation 20 ms Pulse 0.002 0.01 %/W
Adjustment Pin Current 50 100 µA
Adjustment Pin Current Change 10 mA ≤I
OUT
≤3A, 3V ≤(V
IN
−V
OUT
)≤35V 0.2 5 µA
Temperature Stability T
MIN
≤T
J
≤T
MAX
1%
Minimum Load Current V
IN
−V
OUT
= 35V 3.5 5 mA
Current Limit V
IN
−V
OUT
≤10V 3.0 4.5 A
V
IN
−V
OUT
= 30V 0.3 1 A
RMS Output Noise, % of V
OUT
10 Hz ≤f≤10 kHz 0.001 %
Ripple Rejection Ratio V
OUT
= 10V, f = 120 Hz, C
ADJ
=0µF 65 dB
V
OUT
= 10V, f = 120 Hz, C
ADJ
=10µF 66 86 dB
Long-Term Stability T
J
= 125˚C, 1000 hrs 0.3 1 %
Thermal Resistance, Junction K Package 1.2 1.5 ˚C/W
to Case
Thermal Resistance, Junction K Package 35 ˚C/W
to Ambient (No Heat Sink)
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, V
IN
−V
OUT
= 5V, and I
OUT
= 10 mA. (Note 2)
Parameter Conditions LM350A LM350 Units
Min Typ Max Min Typ Max
Reference Voltage I
OUT
= 10 mA, T
J
= 25˚C 1.238 1.250 1.262 V
3V ≤(V
IN
−V
OUT
)≤35V, 1.225 1.250 1.270 1.20 1.25 1.30 V
10 mA ≤I
OUT
≤3A, P ≤30W
Line Regulation 3V ≤(V
IN
−V
OUT
)≤35V (Note 3) 0.005 0.01 0.005 0.03 %/V
0.02 0.05 0.02 0.07 %/V
Load Regulation 10 mA ≤I
OUT
≤3A (Note 3) 0.1 0.3 0.1 0.5 %
LM150/LM350A/LM350
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Electrical Characteristics (Continued)
Specifications with standard type face are for T
J
= 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, V
IN
−V
OUT
= 5V, and I
OUT
= 10 mA. (Note 2)
Parameter Conditions LM350A LM350 Units
Min Typ Max Min Typ Max
0.3 1 0.3 1.5 %
Thermal Regulation 20 ms Pulse 0.002 0.01 0.002 0.03 %/W
Adjustment Pin Current 50 100 50 100 µA
Adjustment Pin Current Change 10 mA ≤I
OUT
≤3A, 3V ≤(V
IN
−V
OUT
)≤35V 0.2 5 0.2 5 µA
Temperature Stability T
MIN
≤T
J
≤T
MAX
11%
Minimum Load Current V
IN
−V
OUT
= 35V 3.5 10 3.5 10 mA
Current Limit V
IN
−V
OUT
≤10V 3.0 4.5 3.0 4.5 A
V
IN
−V
OUT
= 30V 0.3 1 0.25 1 A
RMS Output Noise, % of V
OUT
10 Hz ≤f≤10 kHz 0.001 0.001 %
Ripple Rejection Ratio V
OUT
= 10V, f = 120 Hz, C
ADJ
=0µF 65 65 dB
V
OUT
= 10V, f = 120 Hz, C
ADJ
=10µF 66 86 66 86 dB
Long-Term Stability T
J
= 125˚C, 1000 hrs 0.25 1 0.25 1 %
Thermal Resistance, Junction K Package 1.2 1.5 ˚C/W
to Case T Package 3 4 3 4 ˚C/W
Thermal Resistance, Junction K Package 35 ˚C/W
to Ambient (No Heat Sink) T Package 50 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
intended 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 30W 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 RETS150K drawing for military specifications of the LM150K.
Typical Performance Characteristics
Load Regulation Current Limit
00906133 00906134
LM150/LM350A/LM350
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Typical Performance Characteristics (Continued)
Adjustment Current Dropout Voltage
00906135 00906136
Temperature Stability Minimum Operating Current
00906137 00906138
Ripple Rejection Ripple Rejection
00906139 00906140
LM150/LM350A/LM350
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Typical Performance Characteristics (Continued)
Ripple Rejection Output Impedance
00906141 00906142
Line Transient Response Load Transient Response
00906143 00906144
LM150/LM350A/LM350
www.national.com5
Application Hints
In operation, the LM150 develops a nominal 1.25V reference
voltage, V
REF
, between the output and adjustment terminal.
The reference voltage is impressed across program resistor
R1 and, since the voltage is constant, a constant current I
1
then flows through the output set resistor R2, giving an
output voltage of
Since the 50 µA current from the adjustment terminal repre-
sents an error term, the LM150 was designed to minimize
I
ADJ
and make it very constant with line and load changes.
To do this, all quiescent operating current is returned to the
output establishing a minimum load current requirement. If
there is insufficient load on the output, the output will rise.
EXTERNAL CAPACITORS
An input bypass capacitor is recommended. A 0.1 µF disc or
1 µF solid tantalum on the input is suitable input bypassing
for almost all applications. The device is more sensitive to
the absence of input bypassing when adjustment or output
capacitors are used but the above values will eliminate the
possibility of problems.
The adjustment terminal can be bypassed to ground on the
LM150 to improve ripple rejection. This bypass capacitor
prevents ripple from being amplified as the output voltage is
increased. With a 10 µF bypass capacitor 86 dB ripple
rejection is obtainable at any output level. Increases over
10 µF do not appreciably improve the ripple rejection at
frequencies above 120 Hz. If the bypass capacitor is used, it
is sometimes necessary to include protection diodes to pre-
vent the capacitor from discharging through internal low
current paths and damaging the device.
In general, the best type of capacitors to use is solid tanta-
lum. Solid tantalum capacitors have low impedance even at
high frequencies. Depending upon capacitor construction, it
takes about 25 µF in aluminum electrolytic to equal 1 µF
solid tantalum at high frequencies. Ceramic capacitors are
also good at high frequencies, but some types have a large
decrease in capacitance at frequencies around 0.5 MHz. For
this reason, 0.01 µF disc may seem to work better than a 0.1
µF disc as a bypass.
Although the LM150 is stable with no output capacitors, like
any feedback circuit, certain values of external capacitance
can cause excessive ringing. This occurs with values be-
tween 500 pF and 5000 pF. A 1 µF solid tantalum (or 25 µF
aluminum electrolytic) on the output swamps this effect and
insures stability.
LOAD REGULATION
The LM150 is capable of providing extremely good load
regulation but a few precautions are needed to obtain maxi-
mum performance. The current set resistor connected be-
tween the adjustment terminal and the output terminal (usu-
ally 240Ω) should be tied directly to the output (case) of the
regulator rather than near the load. This eliminates line
drops from appearing effectively in series with the reference
and degrading regulation. For example, a 15V regulator with
0.05Ωresistance between the regulator and load will have a
load regulation due to line resistance of 0.05ΩxI
OUT
.Ifthe
set resistor is connected near the load the effective line
resistance will be 0.05Ω(1 + R2/R1) or in this case, 11.5
times worse.
Figure 2 shows the effect of resistance between the regula-
tor and 240Ωset resistor.
With the TO-3 package, it is easy to minimize the resistance
from the case to the set resistor, by using two separate leads
to the case. The ground of R2 can be returned near the
ground of the load to provide remote ground sensing and
improve load regulation.
PROTECTION DIODES
When external capacitors are used with any IC regulator it is
sometimes necessary to add protection diodes to prevent
the capacitors from discharging through low current points
into the regulator. Most 10 µF capacitors have low enough
internal series resistance to deliver 20A spikes when
shorted. Although the surge is short, there is enough energy
to damage parts of the IC.
When an output capacitor is connected to a regulator and
the input is shorted, the output capacitor will discharge into
the output of the regulator. The discharge current depends
on the value of the capacitor, the output voltage of the
regulator, and the rate of decrease of V
IN
. In the LM150, this
discharge path is through a large junction that is able to
sustain 25A surge with no problem. This is not true of other
types of positive regulators. For output capacitors of 25 µF or
less, there is no need to use diodes.
The bypass capacitor on the adjustment terminal can dis-
charge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to the
LM150 is a 50Ωresistor which limits the peak discharge
current. No protection is needed for output voltages of 25V
00906107
FIGURE 1.
00906108
FIGURE 2. Regulator with Line Resistance
in Output Lead
LM150/LM350A/LM350
www.national.com 6
Application Hints (Continued)
or less and 10 µF capacitance. Figure 3 shows an LM150
with protection diodes included for use with outputs greater
than 25V and high values of output capacitance.
Schematic Diagram
00906110
00906109
D1 protects against C1
D2 protects against C2
FIGURE 3. Regulator with Protection Diodes
LM150/LM350A/LM350
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Typical Applications
1.2V–25V Adjustable Regulator
00906101
Full output current not available
at high input-output voltages.
†Optional — improves transient response. Output capacitors in the range of
1 µF to 1000 µF of aluminum or tantalum electrolytic are commonly used
to provide improved output impedance and rejection of transients.
*Needed if device is more than 6 inches from filter capacitors.
Note: Usually R1 = 240Ωfor LM150 and R1 = 120Ωfor LM350.
Precision Power Regulator with Low Temperature
Coefficient
00906113
*Adjust for 3.75V across R1
Slow Turn-ON 15V Regulator
00906114
Adjustable Regulator with Improved
Ripple Rejection
00906115
†Solid tantalum
*Discharges C1 if output is shorted to ground
High Stability 10V Regulator
00906116
LM150/LM350A/LM350
www.national.com 8
Typical Applications (Continued)
Digitally Selected Outputs
00906117
*Sets maximum VOUT
Regulator and Voltage Reference
00906103
LM150/LM350A/LM350
www.national.com9
Typical Applications (Continued)
10A Regulator
00906118
*Minimum load current 50 mA
5V Logic Regulator with
Electronic Shutdown*
00906119
*Min output ≈1.2V
LM150/LM350A/LM350
www.national.com 10
Typical Applications (Continued)
0 to 30V Regulator
00906120
Full output current not available at high input-output voltages
5A Constant Voltage/Constant Current Regulator
00906121
†Solid tantalum
*Lights in constant current mode
LM150/LM350A/LM350
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Typical Applications (Continued)
12V Battery Charger
00906122
Adjustable Current Regulator
00906123
Precision Current Limiter
00906124
*0.4 ≤R1≤120Ω
1.2V–20V Regulator with
Minimum Program Current
00906125
*Minimum output current ≈4mA
3A Current Regulator
00906126
LM150/LM350A/LM350
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Typical Applications (Continued)
Tracking Preregulator
00906127
Adjusting Multiple On-Card Regulators
with Single Control*
00906128
†Minimum load — 10 mA
*All outputs within ±100 mV
AC Voltage Regulator
00906129
Simple 12V Battery Charger
00906130
00906148
Use of RSallows low charging rates with fully charged battery.
**1000 µF is recommended to filter out any input transients
LM150/LM350A/LM350
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Typical Applications (Continued)
Temperature Controller
00906111
Light Controller
00906112
Adjustable 10A Regulator
00906131
Current Limited 6V Charger
00906132
*Sets peak current (2A for 0.3Ω)
**1000 µF is recommended to filter out any input transients.
6A Regulator
00906102
LM150/LM350A/LM350
www.national.com 14
Physical Dimensions inches (millimeters)
unless otherwise noted
2 Lead TO-3 Metal Can Package (K)
Order Number LM150K STEEL or LM350K STEEL
NS Package Number K02A
2 Lead TO-3 Metal Can Package (K)
Mil-Aero Product
Order Number LM150K/883
NS Package Number K02C
LM150/LM350A/LM350
www.national.com15
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
3 Lead Molded TO-220 (T)
Order Number LM350AT or LM350T
NS Package Number T03B
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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LM150/LM350A/LM350 3-Amp Adjustable Regulators
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