LM317L
3-Terminal Adjustable Regulator
General Description
The LM317L is an adjustable 3-terminal positive voltage regulator capable of supplying 100mA over a 1.2V to 37V output
range. It is exceptionally easy to use and requires only two
external resistors to set the output voltage. Further, both line
and load regulation are better than standard fixed regulators.
Also, the LM317L is available packaged in a standard TO-92
transistor package which is easy to use.
In addition to higher performance than fixed regulators, the
LM317L offers full overload protection. 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 terminal is 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 optional output capacitor can be added to improve transient response. The
adjustment terminal can be bypassed to achieve very high
ripple rejection ratios which are difficult to achieve with standard 3-terminal regulators.
Besides replacing fixed regulators, the LM317L 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.
Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a
fixed resistor between the adjustment and output, the LM317L
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 LM317L is available in a standard TO-92 transistor package, the SO-8 package, and 6-Bump micro SMD package.
The LM317L is rated for operation over a −25°C to 125°C
range.
Features
Adjustable output down to 1.2V
■
Guaranteed 100mA output current
■
Line regulation typically 0.01%V
■
Load regulation typically 0.1%
■
Current limit constant with temperature
■
Eliminates the need to stock many voltages
■
Standard 3-lead transistor package
■
80dB ripple rejection
■
Available in TO-92, SO-8, or 6-Bump micro SMD package
■
Output is short circuit protected
■
See AN-1112 for micro SMD considerations
■
LM317L 3-Terminal Adjustable Regulator
April 9, 2008
Connection Diagrams
TO-92 Plastic package
906404
© 2008 National Semiconductor Corporation 9064 www.national.com
8-Pin SOIC
Top View
906405
LM317L
6-Bump micro SMD
micro SMD Laser Mark
906450
*NC = Not Internally connected.
906449
Top View
(Bump Side Down)
Ordering Information
Package Part Number Package Marking Media Transport NSC Drawing
TO-92 LM317LZ LM317LZ 1.8k Units per Box Z03A
8-Pin SOIC LM317LM LM317LM Rails M08A
* LM317LIBP
6-Bump micro SMD
* LM317LIBPX
* LM317LITP
* LM317LITPX
Note:
The micro SMD package marking is a single digit manufacturing Date
Code only.
–
–
–
–
250 Units Tape and Reel
3k Units Tape and Reel
250 Units Tape and Reel
3k Units Tape and Reel
BPA06HPB
TPA06HPA
www.national.com 2
LM317L
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Power Dissipation Internally Limited
Input-Output Voltage Differential 40V
Storage Temperature −55°C to +150°C
Lead Temperature
(Soldering, 4 seconds) 260°C
Output is Short Circuit Protected
ESD Susceptibility
Human Body Model (Note 5) 2kV
Operating Junction Temperature
Range −40°C to +125°C
Electrical Characteristics (Note 2)
Parameter Conditions Min Typ Max Units
Line Regulation
Load Regulation
TJ = 25°C, 3V ≤ (VIN − V
TJ = 25°C, 5mA ≤ I
OUT
) ≤ 40V, IL ≤ 20mA (Note 3)
OUT
≤ I
, (Note 3)
MAX
Thermal Regulation TJ = 25°C, 10ms Pulse 0.04 0.2 %/W
Adjustment Pin Current 50 100
Adjustment Pin Current
Change
Reference Voltage
Line Regulation
Load Regulation
Temperature Stability
Minimum Load Current
Current Limit
(VIN − V
Rms Output Noise, % of V
OUT
Ripple Rejection Ratio V
5mA ≤ IL ≤ 100mA
3V ≤ (VIN − V
3V ≤ (VIN − V
5mA ≤ I
OUT
3V ≤ (VIN − V
5mA ≤ I
T
(VIN − V
≤ TJ ≤ T
MIN
OUT
OUT
3V ≤ (VIN − V
3V ≤ (VIN − V
OUT
) ≤ 40V, P ≤ 625mW
OUT
) ≤ 40V, (Note 4)
OUT
≤ 100mA, P ≤ 625mW
) ≤ 40V, IL ≤ 20mA (Note 3)
OUT
≤ 100mA, (Note 3)
Max
) ≤ 40V
) ≤ 15V
OUT
) ≤ 13V
OUT
) = 40V 25 50 150 mA
TJ = 25°C, 10Hz ≤ f ≤ 10kHz
= 10V, f = 120Hz, C
C
OUT
ADJ
= 10μF
ADJ
= 0 65 dB
Long-Term Stability TJ = 125°C, 1000 Hours 0.3 1 %
Thermal Resistance Z Package 0.4″ Leads 180 °C/W
Junction to Ambient Z Package 0.125 Leads 160 °C/W
SO-8 Package 165 °C/W
6-Bump micro SMD 290 °C/W
0.01 0.04 %/V
0.1 0.5 %
μA
0.2 5
μA
1.20 1.25 1.30 V
0.02 0.07 %/V
0.3 1.5 %
0.65 %
3.5 5 mA
1.5 2.5
100 200 300 mA
0.003 %
66 80 dB
Note 1: “Absolute Maximum Ratings” 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.
Note 2: Unless otherwise noted, these specifications apply: −25°C ≤ Tj ≤ 125°C for the LM317L; VIN − V
is internally limited, these specifications are applicable for power dissipations up to 625mW. I
Note 3: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specification for thermal regulation.
Note 4: Thermal resistance of the TO-92 package is 180°C/W junction to ambient with 0.4″ leads from a PC board and 160°C/W junction to ambient with 0.125″
lead length to PC board.
Note 5: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
3 www.national.com
is 100mA.
MAX
= 5V and I
OUT
= 40mA. Although power dissipation
OUT
Typical Performance Characteristics (Output capacitor = 0μF unless otherwise noted.)
LM317L
Load Regulation
Adjustment Current
906434
Current Limit
906435
Dropout Voltage
906436
Reference Voltage Temperature Stability
906438
906437
Minimum Operating Current
906439
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LM317L
Ripple Rejection
Output Impedance
906440
Ripple Rejection
906441
Line Transient Response
Load Transient Response
906442
906444
906443
Thermal Regulation
906445
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Application Hints
In operation, the LM317L develops a nominal 1.25V reference
LM317L
voltage, V
The reference voltage is impressed across program resistor
R1 and, since the voltage is constant, a constant current I
then flows through the output set resistor R2, giving an output
voltage of
Since the 100μA current from the adjustment terminal represents an error term, the LM317L was designed to minimize
I
and make it very constant with line and load changes. To
ADJ
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.
, between the output and adjustment terminal.
REF
Although the LM317L is stable with no output capacitors, like
any feedback circuit, certain values of external capacitance
can cause excessive ringing. This occurs with values between 500pF and 5000pF. A 1μF solid tantalum (or 25μF
aluminum electrolytic) on the output swamps this effect and
1
insures stability.
LOAD REGULATION
The LM317L is capable of providing extremely good load regulation but a few precautions are needed to obtain maximum
performance. The current set resistor connected between the
adjustment terminal and the output terminal (usually 240Ω)
should be tied directly to the output 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 0.05Ω resistance
between the regulator and load will have a load regulation due
to line resistance of 0.05Ω × IL. If the 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 regulator
and 240Ω set resistor.
With the TO-92 package, it is easy to minimize the resistance
from the case to the set resistor, by using two separate leads
to the output pin. The ground of R2 can be returned near the
ground of the load to provide remote ground sensing and improve load regulation.
906407
FIGURE 1.
EXTERNAL CAPACITORS
An input bypass capacitor is recommended in case the regulator is more than 6 inches away from the usual large filter
capacitor. A 0.1μF disc or 1μF 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
LM317L to improve ripple rejection and noise. This bypass
capacitor prevents ripple and noise from being amplified as
the output voltage is increased. With a 10μF bypass capacitor
80dB ripple rejection is obtainable at any output level. Increases over 10μF do not appreciably improve the ripple
rejection at frequencies above 120Hz. If the bypass capacitor
is used, it is sometimes necessary to include protection
diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.
In general, the best type of capacitors to use is solid tantalum.
Solid tantalum capacitors have low impedance even at high
frequencies. Depending upon capacitor construction, it takes
about 25μF in aluminum electrolytic to equal 1μF 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 0.5MHz. For this reason,
a 0.01μF disc may seem to work better than a 0.1μF disc as
a bypass.
906408
FIGURE 2. Regulator with Line Resistance
in Output Lead
THERMAL REGULATION
When power is dissipated in an IC, a temperature gradient
occurs across the IC chip affecting the individual IC circuit
components. With an IC regulator, this gradient can be especially severe since power dissipation is large. Thermal regulation is the effect of these temperature gradients on output
voltage (in percentage output change) per watt of power
change in a specified time. Thermal regulation error is independent of electrical regulation or temperature coefficient,
and occurs within 5ms to 50ms after a change in power dissipation. Thermal regulation depends on IC layout as well as
electrical design. The thermal regulation of a voltage regulator
is defined as the percentage change of V
the first 10ms after a step of power is applied. The LM317L
, per watt, within
OUT
specification is 0.2%/W, maximum.
In the Thermal Regulation curve at the bottom of the Typical
Performance Characteristics page, a typical LM317L's output
changes only 7mV (or 0.07% of V
pulse is applied for 10ms. This performance is thus well inside
= −10V) when a 1W
OUT
the specification limit of 0.2%/W × 1W = 0.2% maximum.
When the 1W pulse is ended, the thermal regulation again
shows a 7mV change as the gradients across the LM317L
www.national.com 6
LM317L
chip die out. Note that the load regulation error of about 14mV
(0.14%) is additional to the thermal regulation error.
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 10μF 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 VIN. In the LM317L, this discharge path
is through a large junction that is able to sustain a 2A surge
with no problem. This is not true of other types of positive
regulators. For output capacitors of 25 μF or less, the
LM317L's ballast resistors and output structure limit the peak
current to a low enough level so that there is no need to use
a protection diode.
The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs when
either the input or output is shorted. Internal to the LM317L is
a 50Ω resistor which limits the peak discharge current. No
protection is needed for output voltages of 25V or less and
10μF capacitance. Figure 3 shows an LM317L with protection
diodes included for use with outputs greater than 25V and
high values of output capacitance.
D1 protects against C1
D2 protects against C2
FIGURE 3. Regulator with Protection Diodes
LM317L micro SMD Light Sensitivity
Exposing the LM317L micro SMD package to bright sunlight
may cause the V
of fluorescent lighting the output is not affected. The LM317
to drop. In a normal office environment
REF
906409
micro SMD does not sustain permanent damage from light
exposure. Removing the light source will cause LM317L's
V
to recover to the proper value.
REF
7 www.national.com
LM317L
906410
Schematic Diagram
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LM317L
Typical Applications
Digitally Selected Outputs
*Sets maximum V
OUT
High Gain Amplifier
Slow Turn-On 15V Regulator
906415
Adjustable Regulator with
Improved Ripple Rejection
906411
906416
†Solid tantalum
*Discharges C1 if output is shorted to ground
12 ≤ R1 ≤ 240
906412
Adjustable Current Limiter
Precision Current Limiter
High Stability 10V Regulator
906413
906417
Adjustable Regulator with Current Limiter
906414
Short circuit current is approximately 600 mV/R3, or 60mA (compared to
LM317LZ's 200mA current limit).
At 25mA output only 3/4V of drop occurs in R3 and R4.
906418
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LM317L
0V–30V Regulator
Power Follower
Full output current not available at high input-output voltages
906419
Regulator With 15mA Short Circuit Current
906420
Adjusting Multiple On-Card Regulators with Single Control*
906421
*All outputs within ± 100mV
†Minimum load −5mA
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906422
LM317L
100mA Current Regulator
906423
1.2V–12V Regulator with Minimum Program Current
906424
*Minimum load current ≈ 2 mA
50mA Constant Current Battery
Charger for Nickel-Cadmium
Batteries
5V Logic Regulator with Electronic Shutdown*
*Minimum output ≈ 1.2V
Current Limited 6V Charger
*Sets peak current, I
**1000μF is recommended to filter out any input transients.
PEAK
= 0.6V/R1
906426
906427
906425
11 www.national.com
LM317L
Short Circuit Protected 80V Supply
906428
Basic High Voltage Regulator
Q1, Q2: NSD134 or similar
C1, C2: 1μF, 200V mylar**
*Heat sink
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906429
Precision High Voltage Regulator
LM317L
Q1, Q2: NSD134 or similar
C1, C2: 1μF, 200V mylar**
*Heat sink
**Mylar is a registered trademark of DuPont Co.
Tracking Regulator
A1 = LM301A, LM307, or LF13741 only
906431
906430
R1, R2 = matched resistors with good TC tracking
Regulator With Trimmable Output Voltage
Trim Procedure:
—If V
is 23.08V or higher, cut out R3 (if lower, don't cut it out).
OUT
—Then if V
—Then if V
is 22.47V or higher, cut out R4 (if lower, don't).
OUT
is 22.16V or higher, cut out R5 (if lower, don't).
OUT
This will trim the output to well within ±1% of 22.00 VDC, without any of the
expense or uncertainty of a trim pot (see LB-46). Of course, this technique
can be used at any output voltage level.
906432
13 www.national.com
LM317L
Precision Reference with Short-Circuit Proof Output
*R1–R4 from thin-film network,
Beckman 694-3-R2K-D or similar
1.2V-25 Adjustable Regulator
906401
Full output current not available at high input-output voltages
†Optional—improves transient response
*Needed if device is more than 6 inches from filter capacitors
Fully Protected (Bulletproof)
Lamp Driver
906433
Lamp Flasher
906403
Output rate—4 flashes per second at 10% duty cycle
906402
www.national.com 14
Physical Dimensions inches (millimeters) unless otherwise noted
LM317L
SO-8 Molded Package
NS Package Number M08A
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LM317L
TO-92 Plastic Package (Z)
NS Package Number Z03A
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NOTE: UNLESS OTHERWISE SPECIFIED.
1. EPOXY COATING
2. 63Sn/37Pb EUTECTIC BUMP.
3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION PINS ARE NUMBERED COUNTERCLOCKWISE.
5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE
HEIGHT.
6. REFERENCE JEDEC REGISTRATION MO-211, VARIATION BC.
6-Bump micro SMD
NS Package Number BPA06HPB
X1 = 0.955 X2 = 1.615 X3 =0.850
LM317L
17 www.national.com
LM317L
NOTE: UNLESS OTHERWISE SPECIFIED.
1. EPOXY COATING
2. 63Sn/37Pb EUTECTIC BUMP.
3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION PINS ARE NUMBERED COUNTERCLOCKWISE.
5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE
HEIGHT.
6. REFERENCE JEDEC REGISTRATION MO-211, VARIATION BC.
6-Bump micro SMD
NS Package Number TPA06HPA
X1 = 0.955 X2 = 1.615 X3 =0.500
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Notes
LM317L
19 www.national.com
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