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LM317L 3-Terminal Adjustable Regulator
November 2000
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 -25C to 125C range.
Features
Adjustable output down to 1.2V Guaranteed 100 mA 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 80 dB ripple rejection Available in TO-92, SO-8, or 6-Bump micro SMD package n Output is short circuit protected n See AN-1112 for micro SMD considerations n n n n n n n n n
Connection Diagrams
TO-92 Plastic package 8-Pin SOIC
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Top View
(c) 2000 National Semiconductor Corporation
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LM317L
Connection Diagrams
(Continued) micro SMD Laser Mark
6-Bump micro SMD
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*NC = Not Internally connected.
Top View (Bump Side Down) Package TO-92 8-Pin SOIC 6-Bump micro SMD Part Number LM317LZ LM317LM
* LM317LIBP * LM317LIBPX
Package Marking LM317LZ LM317LM - -
Media Transport 1.8k Units per Box Rails 250 Units Tape and Reel 3k Units Tape and Reel
NSC Drawing Z03A M08A BPA06HPB
Note: The micro SMD package marking is a single digit manufacturing Date Code only.
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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 Input-Output Voltage Differential Operating Junction Temperature Range Internally Limited 40V -40C to +125C
Storage Temperature Lead Temperature (Soldering, 4 seconds) Output is Short Circuit Protected ESD rating to be determined.
-55C to +150C 260C
Electrical Characteristics (Note 2)
Parameter Line Regulation Load Regulation Thermal Regulation Adjustment Pin Current Adjustment Pin Current Change Reference Voltage Line Regulation Load Regulation Temperature Stability Minimum Load Current Current Limit Rms Output Noise, % of VOUT Ripple Rejection Ratio Long-Term Stability Thermal Resistance Junction to Ambient 5mA IL 100mA 3V (VIN - VOUT) 40V, P 625mW 3V (VIN - VOUT) 40V, (Note 4) 5mA IOUT 100mA, P 625mW 3V (VIN - VOUT) 40V, IL 20mA (Note 3) 5mA IOUT 100mA, (Note 3) TMIN TJ TMax (VIN - VOUT) 40V 3V (VIN - VOUT) 15V 3V (VIN - VOUT) 13V (VIN - VOUT) = 40V TJ = 25C, 10Hz f 10kHz VOUT = 10V, f = 120Hz, CADJ = 0 CADJ = 10F TJ = 125C, 1000 Hours Z Package 0.4" Leads Z Package 0.125 Leads SO-8 Package 6-Bump micro SMD Thermal Rating of SO Package 66 100 25 0.02 0.3 0.65 3.5 1.5 200 50 0.003 65 80 0.3 180 160 165 290 165 1 5 2.5 300 150 mA mA % dB dB % C/W C/W C/W C/W C/W 0.07 1.5 %/V % % mA 1.20 1.25 1.30 V Conditions TJ = 25C, 3V (VIN - VOUT) 40V, IL 20mA (Note 3) TJ = 25C, 5mA IOUT IMAX, (Note 3) TJ = 25C, 10ms Pulse Min Typ 0.01 0.1 0.04 50 0.2 Max 0.04 0.5 0.2 100 5 Units %/V % %/W A A
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: -25C Tj 125C for the LM317L; VIN - VOUT = 5V and IOUT = 40 mA. Although power dissipation is internally limited, these specifications are applicable for power dissipations up to 625 mW. IMAX is 100 mA. 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 180C/W junction to ambient with 0.4" leads from a PC board and 160C/W junction to ambient with 0.125" lead length to PC board.
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LM317L
Typical Performance Characteristics
Load Regulation
(Output capacitor = 0F unless otherwise noted.) Current Limit
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Adjustment Current
Dropout Voltage
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Reference Voltage Temperature Stability
Minimum Operating Current
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LM317L
Typical Performance Characteristics
Ripple Rejection
(Output capacitor = 0F unless otherwise noted.) (Continued) Ripple Rejection
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Output Impedance
Line Transient Response
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Load Transient Response
Thermal Regulation
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LM317L
Application Hints
In operation, the LM317L develops a nominal 1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program resistor R1 and, since the voltage is constant, a constant current I1 then flows through the output set resistor R2, giving an output voltage of
tween 500 pF and 5000 pF. A 1F solid tantalum (or 25F aluminum electrolytic) on the output swamps this effect and 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 240) 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 0.05 resistance between the regulator and load will have a load regulation due to line resistance of 0.05 x IL. If the set resistor is connected near the load the effective line resistance will be 0.05 (1 + R2/R1) or in this case, 11.5 times worse.
Since the 100A current from the adjustment terminal represents an error term, the LM317L was designed to minimize IADJ 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.
Figure 2 shows the effect of resistance between the regulator and 240 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.
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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 0.1F disc or 1F 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 10F bypass capacitor 80 dB ripple rejection is obtainable at any output level. Increases over 10F 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 25F in aluminum electrolytic to equal 1F 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 0.01F disc may seem to work better than a 0.1F disc as a bypass. 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 be-
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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 VOUT, per watt, within the first 10ms after a step of power is applied. The LM317L 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 VOUT = -10V) when a 1W pulse is applied for 10 ms. This performance is thus well inside the specification limit of 0.2%/W x 1W = 0.2% maximum. When the 1W pulse is ended, the thermal regulation again shows a 7 mV change as the gradients across the LM317L chip die out. Note that the load regulation error of about 14 mV (0.14%) is additional to the thermal regulation error.
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LM317L
Application Hints
Protection Diodes
(Continued)
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 10F 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 F 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 50 resistor which limits the peak discharge current. No protection is needed for output voltages of 25V or less and 10F capacitance. Figure 3 shows an LM317L with protection diodes included for use with outputs greater than 25V and high values of output capacitance.
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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 VREF to drop. In a normal office environment of fluorescent lighting the output is not affected. The LM317 micro SMD does not sustain permanent damage from light exposure. Removing the light source will cause LM317L's VREF to recover to the proper value.
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LM317L
Schematic Diagram
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LM317L
Typical Applications
Digitally Selected Outputs High Gain Amplifier
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*Sets maximum VOUT
Adjustable Current Limiter
Precision Current Limiter
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12 R1 240
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Slow Turn-On 15V Regulator
Adjustable Regulator with Improved Ripple Rejection
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Solid tantalum *Discharges C1 if output is shorted to ground
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LM317L
Typical Applications
(Continued) Adjustable Regulator with Current Limiter
High Stability 10V Regulator
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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.
0V-30V Regulator
Regulator With 15mA Short Circuit Current
Power Follower
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Full output current not available at high input-output voltages
Adjusting Multiple On-Card Regulators with Single Control*
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*All outputs within 100mV Minimum load -5mA
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LM317L
Typical Applications
100mA Current Regulator
(Continued) 1.2V-12V Regulator with Minimum Program Current 50mA Constant Current Battery Charger for Nickel-Cadmium Batteries
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*Minimum load current 2 mA
5V Logic Regulator with Electronic Shutdown*
Current Limited 6V Charger
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*Minimum output 1.2V
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*Sets peak current, IPEAK = 0.6V/R1 **1000F is recommended to filter out any input transients.
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LM317L
Typical Applications
(Continued) Short Circuit Protected 80V Supply
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Basic High Voltage Regulator
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Q1, Q2: NSD134 or similar C1, C2: 1F, 200V mylar** *Heat sink
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LM317L
Typical Applications
(Continued) Precision High Voltage Regulator
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Q1, Q2: NSD134 or similar C1, C2: 1F, 200V mylar** *Heat sink **Mylar is a registered trademark of DuPont Co.
Tracking Regulator
Regulator With Trimmable Output Voltage
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Trim Procedure: -- If VOUT is 23.08V or higher, cut out R3 (if lower, don't cut it out). -- Then if VOUT is 22.47V or higher, cut out R4 (if lower, don't). -- Then if VOUT is 22.16V or higher, cut out R5 (if lower, don't). 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.
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A1 = LM301A, LM307, or LF13741 only R1, R2 = matched resistors with good TC tracking
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LM317L
Typical Applications
(Continued) Precision Reference with Short-Circuit Proof Output
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*R1-R4 from thin-film network,
Beckman 694-3-R2K-D or similar
1.2V-25 Adjustable Regulator
Fully Protected (Bulletproof) Lamp Driver
Lamp Flasher
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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
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Output rate -- 4 flashes per second at 10% duty cycle
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LM317L
Physical Dimensions
inches (millimeters) unless otherwise noted
SO-8 Molded Package NS Package Number M08A
TO-92 Plastic Package (Z) NS Package Number Z03A
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LM317L
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
NOTE: UNLESS OTHERWISE SPECIFIED. 1. EPOXY COATING 2. 63Sn/37Pb EUTECTIC BUMP. 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN 1 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
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LM317L 3-Terminal Adjustable Regulator
Notes
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.
National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: support@nsc.com www.national.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Francais Tel: +33 (0) 1 41 91 8790
2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com
National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507
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.

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