LM337L 3-Terminal Adjustable Regulator General Description The LM337L is an adjustable 3-terminal negative voltage regulator capable of supplying 100 mA 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. Furthermore, both line and load regulation are better than standard fixed regulators. Also, the LM337L is packaged in a standard TO-92 transistor package which is easy to use. In addition to higher performance than fixed regulators, the LM337L 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, only a single 1 µF solid tantalum output capacitor is needed unless the device is situated more than 6 inches from the input filter capacitors, in which case an input bypass is needed. A larger 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 LM337L 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 LM337L 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 LM337L is available in a standard TO-92 transistor package and a SO-8 surface mount package. The LM337L is rated for operation over a −25˚C to +125˚C range. For applications requiring greater output current in excess of 0.5A and 1.5A, see LM137 series data sheets. For the positive complement, see series LM117 and LM317L data sheets. Features n n n n n n n n n 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 Output is short circuit protected Connection Diagram DS009134-1 Bottom View DS009134-2 Top View Order Number LM337LM or LM337LZ See NS Package Number M08A or Z03A © 1999 National Semiconductor Corporation DS009134 www.national.com LM337L 3-Terminal Adjustable Regulator May 1998 Absolute Maximum Ratings (Note 1) Storage Temperature Lead Temperature (Soldering, 10 sec.) Plastic Package (Soldering 4 sec.) ESD rating to be determined. 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 −55˚C to +150˚C 300˚C 260˚C −25˚C to +125˚C Electrical Characteristics (Note 2) Parameter Line Regulation Load Regulation Thermal Regulation Conditions TA = 25˚C, 3V ≤ |VIN − VOUT| ≤ 40V, Min Max Units 0.04 %/V (Note 3) TA = 25˚C, 5 mA ≤ IOUT ≤ IMAX, (Note 3) TA = 25˚C, 10 ms Pulse 0.1 0.5 % 0.04 0.2 %/W 50 100 µA 5 mA ≤ IL ≤ 100 mA 0.2 5 µA 1.25 1.30 V %/V Adjustment Pin Current Adjustment Pin Current Change Typ 0.01 3V ≤ |VIN − VOUT| ≤ 40V Reference Voltage 3V ≤ |VIN − VOUT| ≤ 40V, (Note 4) 1.20 10 mA ≤ IOUT ≤ 100 mA, P ≤ 625 mW Line Regulation 3V ≤ |VIN − VOUT| ≤ 40V, (Note 3) 0.02 0.07 Load Regulation 5 mA ≤ IOUT ≤ 100 mA, (Note 3) 0.3 1.5 Temperature Stability TMIN ≤ Tj ≤ TMAX 0.65 Minimum Load Current |VIN − VOUT| ≤ 40V 3.5 5 mA 3V ≤ |VIN − VOUT| ≤ 15V 2.2 3.5 mA 100 200 320 mA 25 50 120 mA Current Limit 3V ≤ |VIN − VOUT| ≤ 13V |VIN − VOUT| = 40V Ripple Rejection Ratio TA = 25˚C, 10 Hz ≤ f ≤ 10 kHz VOUT = −10V, F = 120 Hz, CADJ = 0 CADJ = 10 µF Long-Term Stability TA = 125˚C Rms Output Noise, % of VOUT 66 % % 0.003 % 65 dB 80 0.3 dB 1 % 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 specified, these specifications apply −25˚C ≤ Tj ≤ + 125˚C for the LM337L; |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 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. The M package θJA is 180˚C/W in still air. www.national.com 2 Typical Applications 1.2V-25V Adjustable Regulator Regulator with Trimmable Output Voltage DS009134-3 Full output current not available at high input-output voltages DS009134-4 Trim Procedure: — If VOUT is −23.08V or bigger, cut out R3 (if smaller, don’t cut it out). — Then if VOUT is −22.47V or bigger, cut out R4 (if smaller, don’t). — Then if VOUT is −22.16V or bigger, cut out R5 (if smaller, don’t). This will trim the output to well within 1% of −22.00 VDC, without any of the expense or trouble of a trim pot (see LB-46). Of course, this technique can be used at any output voltage level. †C1 = 1 µF solid tantalum or 10 µF aluminum electrolytic required for stability *C2 = 1 µF solid tantalum is required only if regulator is more than 4" from power supply filter capacitor 3 www.national.com Physical Dimensions inches (millimeters) unless otherwise noted SO-8 Plastic Package (M) Order Number LM337LM NS Package Number M08A TO-92 Plastic Package (Z) Order Number LM337LZ NS Package Number Z03A www.national.com 4 LM337L 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: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Français Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 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. 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