LM2990

LM2990 Negative Low Dropout Regulator June 1999 LM2990 Negative Low Dropout Regulator General Description The LM2990 is a three-terminal, low dropout, 1 ampere negative voltage regulator available with fixed output voltages of −5, −5.2, −12, and −15V. The LM2990 uses new circuit design techniques to provide low dropout and low quiescent current. The dropout voltage at 1A load current is typically 0.6V and a guaranteed worst-case maximum of 1V over the entire operating temperature range. The quiescent current is typically 1 mA with 1A load current and an input-output voltage differential greater than 3V. A unique circuit design of the internal bias supply limits the quiescent current to only 9 mA (typical) when the regulator is in the dropout mode (VOUT − VIN ≤ 3V). Output voltage accuracy is guaranteed to ± 5% over load, and temperature extremes. The LM2990 is short-circuit proof, and thermal shutdown includes hysteresis to enhance the reliability of the device when overloaded for an extended period of time. The LM2990 is available in a 3-lead TO-220 package and is rated for operation over the automotive temperature range of −40˚C to +125˚C. Features n n n n n n n 5% output accuracy over entire operating range Output current in excess of 1A Dropout voltage typically 0.6V at 1A load Low quiescent current Internal short circuit current limit Internal thermal shutdown with hysteresis Functional complement to the LM2940 series Applications n Post switcher regulator n Local, on-card, regulation n Battery operated equipment Typical Application DS010801-1 *Required if the regulator is located further than 6 inches from the power supply filter capacitors. A 1 µF solid tantalum or a 10 µF aluminum electrolytic capacitor is recommended. **Required for stability. Must be at least a 10 µF aluminum electrolytic or a 1 µF solid tantalum to maintain stability. May be increased without bound to maintain regulation during transients. Locate the capacitor as close as possible to the regulator. The equivalent series resistance (ESR) is critical, and should be less than 10Ω over the same operating temperature range as the regulator. Ordering Information and Connection Diagrams Temperature Range −40˚C to +125˚C −55˚C to +125˚C Output Voltage -5.0 LM2990T-5.0 LM2990S-5.0 LM2990J-5.0-QML 5962-9571101QEA LM2990WG5.0-QML 5962-9571101QXA -5.2 LM2990T-5.2 -12 LM2990T-12 LM2990S-12 LM2990J-12-QML 5962-9571001QEA -15 LM2990T-15 LM2990S-15 LM2990J-15-QML 5962-9570901QEA TO-220 TO-263 J16A WG16A Package © 1999 National Semiconductor Corporation DS010801 www.national.com Ordering Information and Connection Diagrams (Continued) 3-Lead TO-220 TO-263 Surface-Mount Package DS010801-11 Top View DS010801-2 Front View Order Number LM2990T-5.0, LM2990T-5.2, LM2990T-12 or LM2990T-15 See NS Package Number T03B DS010801-12 Side View Order Number LM2990S-5.0, LM2990S-12 or LM2990S-15 See NS Package Number TS3B 16-Lead Ceramic Dual-in-Line Package 16-Lead Ceramic Surface Mount Package DS010801-33 Top View Order Number LM2990J-5.0-QML (5962-9571101QEA), LM2990J-12-QML (5962-9571001QEA), or LM2990J-15-QML (5962-9570901QEA), See NS Package Number J16A DS010801-34 Top View Order Number LM2990WG5.0-QML (5962-9571101QXEA) See NS Package Number WG16A www.national.com 2 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Voltage ESD Susceptibility (Note 2) Power Dissipation (Note 3) Junction Temperature (TJmax) −26V to +0.3V 2 kV Internally Limited 125˚C Storage Temperature Lead Temperature (Soldering, 10 sec.) −65˚C to +150˚C 260˚C Operating Ratings(Note 1) Junction Temperature Range (TJ) Maximum Input Voltage (Operational) −40˚C to +125˚C −26V Electrical Characteristics VIN = −5V + VO(NOM) (Note 6) , IO = 1A, CO = 47 µF, unless otherwise specified. Boldface limits apply over the entire operating temperature range, −40˚C ≤ TJ ≤ 125˚C, all other limits apply for TJ = 25˚C. LM2990-5.0 Parameter Output Voltage (VO) Conditions 5 mA ≤ IO ≤ 1A −5 5 mA ≤ IO ≤ 1A Line Regulation Load Regulation Dropout Voltage Quiescent Current (Iq) Short Circuit Current Maximum Output Current Ripple Rejection Output Noise Voltage Long Term Stability IO = 5 mA, VO(NOM) −1V > VIN > −26V 50 mA ≤ IO ≤ 1A IO = 0.1A, ∆VO ≤ 100 mV IO = 1A, ∆VO ≤ 100 mV IO ≤ 1A IO = 1A, VIN = VO(NOM) RL = 1Ω (Note 7) (Note 7) Vripple = 1 Vrms, ƒripple = 1 kHz, IO = 5 mA 10 Hz–100 kHz, IO = 5 mA 1000 Hours 1 0.1 0.6 1 9 1.8 1.8 58 250 2000 40 0.3 1 5 50 1.5 1.5 50 750 1 0.1 0.6 1 9 1.8 1.8 58 250 2000 40 0.3 1 5 50 1.5 1.5 50 750 mV (max) V (max) V (max) mA (max) mA (max) A (min) A (min) dB (min) µV (max) ppm 4 −4.75 −5.25 40 4 Typ (Note 4) Limit (Note 5) −4.90 −5.10 −5.2 −4.94 −5.46 40 LM2990-5.2 Typ (Note 4) Limit (Note 5) −5.10 −5.30 V (max) mV (min) V V (max) V (min) mV (max) Units (Limit) Electrical Characteristics VIN = −5V + VO(NOM) (Note 6) , IO = 1A, CO = 47 µF, unless otherwise specified. Boldface limits apply over the entire operating temperature range, −40˚C ≤ TJ ≤ 125˚C, all other limits apply for TJ = 25˚C. LM2990-12 Parameter Output Voltage (VO) Conditions 5 mA ≤ IO ≤ 1A −12 5 mA ≤ IO ≤ 1A Line Regulation Load Regulation Dropout Voltage Quiescent Current (Iq) IO = 5 mA, VO(NOM) −1V > VIN > −26V 50 mA ≤ IO ≤ 1A IO = 0.1A, ∆VO ≤ 100 mV IO = 1A, ∆VO ≤ 100 mV IO ≤ 1A IO = 1A, VIN = VO(NOM) 3 0.1 0.6 1 9 50 0.3 1 5 50 3 0.1 0.6 1 9 50 0.3 1 5 50 mV (max) V (max) V (max) mA (max) mA (max) 6 −11.40 −12.60 60 6 Typ (Note 4) Limit (Note 5) −11.76 −12.24 −15 −14.25 −15.75 60 LM2990-15 Typ (Note 4) Limit (Note 5) −14.70 −15.30 V (max) V (min) V V (max) V (min) mV (max) Units (Limit) 3 www.national.com Electrical Characteristics (Continued) VIN = −5V + VO(NOM) (Note 6) , IO = 1A, CO = 47 µF, unless otherwise specified. Boldface limits apply over the entire operating temperature range, −40˚C ≤ TJ ≤ 125˚C, all other limits apply for TJ = 25˚C. LM2990-12 Parameter Short Circuit Current Maximum Output Current Ripple Rejection Output Noise Voltage Long Term Stability Conditions RL = 1Ω (Note 7) (Note 7) Vripple = 1 Vrms, ƒripple = 1 kHz, IO = 5 mA 10 Hz–100 kHz, IO = 5 mA 1000 Hours Typ (Note 4) 1.2 1.8 52 500 2000 Limit (Note 5) 0.9 1.4 42 1500 LM2990-15 Typ (Note 4) 1.0 1.8 52 600 2000 Limit (Note 5) 0.75 1.4 42 1800 A (min) A (min) dB (min) µV (max) ppm Units (Limit) 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: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Note 3: The maximum power dissipation is a function of TJmax, θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJmax − TA)/θJA. If this dissipation is exceeded, the die temperature will rise above 125˚C, and the LM2990 will eventually go into thermal shutdown at a TJ of approximately 160˚C. For the LM2990, the junction-to-ambient thermal resistance, is 53˚C/W, 73˚C/W for the TO-263, and the junction-to-case thermal resistance is 3˚C. If the TO-263 package is used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package. Using 0.5 square inches of copper area, θJA is 50˚C/W; with 1 square inch of copper area, θJA is 37˚C/W; and with 1.6 or more square inches of copper area, θJA is 32˚C/W. Note 4: Typicals are at TJ = 25˚C and represent the most likely parametric norm. Note 5: Limits are guaranteed and 100% production tested. Note 6: VO(NOM) is the nominal (typical) regulator output voltage, −5V, −5.2V, −12V or −15V. Note 7: The short circuit current is less than the maximum output current with the −12V and −15V versions due to internal foldback current limiting. The −5V and −5.2V versions, tested with a lower input voltage, does not reach the foldback current limit and therefore conducts a higher short circuit current level. If the LM2990 output is pulled above ground, the maximum allowed current sunk back into the LM2990 is 1.5A. Definition of Terms Dropout Voltage: The input-output voltage differential at which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has dropped 100 mV from the nominal value obtained at (VO + 5V) input, dropout voltage is dependent upon load current and junction temperature. Input Voltage: The DC voltage applied to the input terminals with respect to ground. Input-Output Differential: The voltage difference between the unregulated input voltage and the regulated output voltage for which the regulator will operate. Line Regulation: The change in output voltage for a change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected. Load Regulation: The change in output voltage for a change in load current at constant chip temperature. Long Term Stability: Output voltage stability under accellerated life-test conditions after 1000 hours with maximum rated voltage and junction temperature. Output Noise Voltage: The rms AC voltage at the output, with constant load and no input ripple, measured over a specified frequency range. Quiescent Current: That part of the positive input current that does not contribute to the positive load current. The regulator ground lead current. Ripple Rejection: The ratio of the peak-to-peak input ripple voltage to the peak-to-peak output ripple voltage. Temperature Stability of VO: The percentage change in output voltage for a thermal variation from room temperature to either temperature extreme. www.national.com 4 Typical Performance Characteristics Dropout Voltage Normalized Output Voltage LM2990-5.0 and LM2990-5.2 Quiescent Current DS010801-14 DS010801-15 DS010801-16 LM2990-12 Quiescent Current LM2990-15 Quiescent Current LM2990-5 and LM2990-5.2 Low Voltage Behavior DS010801-17 DS010801-18 DS010801-19 LM2990-5 and LM2990-5.2 Line Transient Response LM2990-5 and LM2990-5.2 Load Transient Response LM2990-12 and LM2990-15 Low Voltage Behavior DS010801-20 DS010801-21 DS010801-22 LM2990-12 and LM2990-15 Line Transient Response LM2990-12 and LM2990-15 Load Transient Response DS010801-23 DS010801-24 5 www.national.com Typical Performance Characteristics LM2990-5 and LM2990-5.2 Ripple Rejection (Continued) LM2990-5 and LM2990-5.2 Output Impedance Maximum Output Current DS010801-27 DS010801-25 DS010801-26 LM2990-12 and LM2990-15 Ripple Rejection LM2990-12 and LM2990-15 Output Impedance Maximum Output Current DS010801-30 DS010801-28 DS010801-29 Maximum Power Dissipation (TO-220) Maximum Power Dissipation (TO-263) (See (Note 3)) DS010801-31 DS010801-32 www.national.com 6 Typical Applications Post Regulator for an Isolated Switching Power Supply DS010801-5 The LM2940 is a positive 1A low dropout regulator; refer to its datasheet for further information. Fixed Current Sink Adjustable Current Sink DS010801-7 DS010801-10 Application Hints EXTERNAL CAPACITORS The LM2990 regulator requires an output capacitor to maintain stability. The capacitor must be at least 10 µF aluminum electrolytic or 1 µF solid tantalum. The output capacitor’s ESR must be less than 10Ω, or the zero added to the regulator frequency response by the ESR could reduce the phase margin, creating oscillations (refer to the graph on the right). An input capacitor, of at least 1 µF solid tantalum or 10 µF aluminum electrolytic, is also needed if the regulator is situated more than 6" from the input power supply filter. FORCING THE OUTPUT POSITIVE Due to an internal clamp circuit, the LM2990 can withstand positive voltages on its output. If the voltage source pulling the output positive is DC, the current must be limited to 1.5A. A current over 1.5A fed back into the LM2990 could damage the device. The LM2990 output can also withstand fast positive voltage transients up to 26V, without any current limiting of the source. However, if the transients have a duration of over 1 ms, the output should be clamped with a Schottky diode to ground. Output Capacitor ESR DS010801-9 7 www.national.com Equivalent Schematic DS010801-8 www.national.com 8 Physical Dimensions inches (millimeters) unless otherwise noted TO-220 3–Lead Molded Package Order Number LM2990T-5.0, LM2990T-5.2, LM2990T-12 or LM2990T-15 NS Package Number T03B 9 www.national.com Physical Dimensions inches (millimeters) unless otherwise noted (Continued) TO-263 3-Lead Plastic Surface Mount Package Order Number LM2990S-5.0, LM2990S-12 or LM2990S-15 NS Package Number TS3B www.national.com 10 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 16–Lead Ceramic Dual–in–Line Package LM2990J-5.0-QML (5962-9571101QEA), LM2990J-12-QML (5962-9571001QEA), or LM2990J-15-QML (5962-9570901QEA), NS Package Number J16A 16–Lead Ceramic Surface–Mount Package LM2990WG5.0-QML (5962-9571101QXA) NS Package Number WG16A 11 www.national.com LM2990 Negative Low Dropout 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) 1 80-530 85 86 Email: europe.support@nsc.com 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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