LM79XX

LM79XX Series 3-Terminal Negative Regulators November 1994 LM79XX Series 3-Terminal Negative Regulators General Description The LM79XX series of 3-terminal regulators is available with fixed output voltages of b5V b8V b12V and b15V These devices need only one external component a compensation capacitor at the output The LM79XX series is packaged in the TO-220 power package and is capable of supplying 1 5A of output current These regulators employ internal current limiting safe area protection and thermal shutdown for protection against virtually all overload conditions Low ground pin current of the LM79XX series allows output voltage to be easily boosted above the preset value with a resistor divider The low quiescent current drain of these devices with a specified maximum change with line and load ensures good regulation in the voltage boosted mode For applications requiring other voltages see LM137 data sheet Features Y Y Y Y Thermal short circuit and safe area protection High ripple rejection 1 5A output current 4% tolerance on preset output voltage Connection Diagrams TO-220 Package Typical Applications Fixed Regulator TL H 7340 – 3 TL H 7340 – 14 Front View Order Number LM7905CT LM7912CT or LM7915CT See NS Package Number TO3B Required if regulator is separated from filter capacitor by more than 3 For value given capacitor must be solid tantalum 25 mF aluminum electrolytic may be substituted Required for stability For value given capacitor must be solid tantalum 25 mF aluminum electrolytic may be substituted Values given may be increased without limit For output capacitance in excess of 100 mF a high current diode from input to output (1N4001 etc ) will protect the regulator from momentary input shorts C1995 National Semiconductor Corporation TL H 7340 RRD-B30M115 Printed in U S A 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 (Vo e b5V) (Vo e b12V and b15V) b 25V b 35V Input-Output Differential (Vo e b5V) (Vo e b12V and b15V) 25V 30V Power Dissipation (Note 2) Internally Limited Operating Junction Temperature Range 0 C to a 125 C b 65 C to a 150 C Storage Temperature Range Lead Temperature (Soldering 10 sec ) 230 C Electrical Characteristics Conditions unless otherwise noted IOUT e 500 mA CIN e 2 2 mF COUT e 1 mF 0 C s TJ s a 125 C Power Dissipation s 1 5W Part Number Output Voltage Input Voltage (unless otherwise specified) Symbol VO Parameter Output Voltage Conditions TJ e 25 C 5 mA s IOUT s 1A P s 15W TJ e 25 C (Note 3) Min b4 8 b 4 75 LM7905C b 5V b 10V Units Max b5 2 b 5 25 Typ b5 0 (b20 s VIN s b7) 8 (b25 s VIN s b7) 2 (b12 s VIN s b8) 15 5 1 (b25 s VIN s b7) 50 15 V V V mV V mV V mV mV mA mA V mA mV dB V V A mV C D VO Line Regulation D VO Load Regulation TJ e 25 C (Note 3) 5 mA s IOUT s 1 5A 250 mA s IOUT s 750 mA TJ e 25 C With Line With Load 5 mA s IOUT s 1A 100 50 2 05 05 IQ D IQ Quiescent Current Quiescent Current Change Output Noise Voltage Ripple Rejection Dropout Voltage Vn TA e 25 C 10 Hz s f s 100 Hz f e 120 Hz TJ e 25 C IOUT e 1A TJ e 25 C IOUT e 5 mA 0 C s TJ s 100 C 54 125 66 (b18 s VIN s b8) 11 22 04 IOMAX Peak Output Current Average Temperature Coefficient of Output Voltage Typical Applications (Continued) Variable Output TL H 7340 – 2 Improves transient response and ripple rejection Do not increase beyond 50 mF R1 a R2 VOUT e VSET R2 Select R2 as follows LM7905CT 300X LM7912CT 750X LM7915CT 1k  J 2 Electrical Characteristics (Continued) Conditions unless otherwise noted IOUT e 500 mA CIN e 2 2 mF COUT e 1 mF 0 C s TJ s a 125 C Power Dissipation e 1 5W Part Number Output Voltage Input Voltage (unless otherwise specified) Symbol VO Parameter Output Voltage Conditions TJ e 25 C 5 mA s IOUT s 1A P s 15W TJ e 25 C (Note 3) Min LM7912C b 12V b 19V LM7915C b 15V b 23V Units Max V V V mV V mV V mV mV mA mA V mA mV dB V V A mV C Typ Max Min Typ b 11 5 b 12 0 b 12 5 b 11 4 b 12 6 (b27 s VIN s b14 5) b 14 4 b 15 0 b 15 6 b 14 25 b 15 75 (b30 s VIN s b17 5) D VO Line Regulation 5 80 (b30 s VIN s b14 5) 3 30 (b22 s VIN s b16) 15 5 15 200 75 3 5 100 (b30 s VINs b17 5) 3 50 (b26 s VIN s b20) 15 5 15 200 75 3 D VO Load Regulation TJ e 25 C (Note 3) 5 mA s IOUT s 1 5A 250 mA s IOUT s 750 mA TJ e 25 C With Line With Load 5 mA s IOUT s 1A IQ D IQ Quiescent Current Quiescent Current Change Output Noise Voltage Ripple Rejection Dropout Voltage 05 (b30 s VIN s b14 5) 05 300 54 70 (b25 s VIN s b15) 11 22 b0 8 05 (b30 sVIN s b17 5) 05 375 54 70 (b30 s VINs b17 5) 11 22 b1 0 Vn TA e 25 C 10 Hz s f s 100 Hz f e 120 Hz TJ e 25 C IOUT e 1A TJ e 25 C IOUT e 5 mA 0 C s TJ s 100 C IOMAX Peak Output Current Average Temperature Coefficient of Output Voltage 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 Refer to Typical Performance Characteristics and Design Considerations for details Note 3 Regulation is measured at a constant junction temperature by pulse testing with a low duty cycle Changes in output voltage due to heating effects must be taken into account Typical Applications (Continued) Dual Trimmed Supply TL H 7340 – 4 3 Design Considerations The LM79XX fixed voltage regulator series has thermal overload protection from excessive power dissipation internal short circuit protection which limits the circuit’s maximum current and output transistor safe-area compensation for reducing the output current as the voltage across the pass transistor is increased Although the internal power dissipation is limited the junction temperature must be kept below the maximum specified temperature (125 C) in order to meet data sheet specifications To calculate the maximum junction temperature or heat sink required the following thermal resistance values should be used Typ iJC CW 30 Max iJC CW 50 Typ iJA CW 60 Max iJA CW 40 Where TJ TA PD iJA iJC iCA iCS iSA e Junction Temperature e Ambient Temperature e Power Dissipation e Junction-to-Ambient Thermal Resistance e Junction-to-Case Thermal Resistance e Case-to-Ambient Thermal Resistance e Case-to-Heat Sink Thermal Resistance e Heat Sink-to-Ambient Thermal Resistance Package TO-220 TJ Max b TA TJ Max TA PD MAX e or iJC a iCA iJA e iCS a iSA (without heat sink) iCA Solving for TJ TJ e TA a PD (iJC a iCA) or e TA a PDiJA (without heat sink) Typical Applications (Continued) Bypass capacitors are necessary for stable operation of the LM79XX series of regulators over the input voltage and output current ranges Output bypass capacitors will improve the transient response by the regulator The bypass capacitors (2 2 mF on the input 1 0 mF on the output) should be ceramic or solid tantalum which have good high frequency characteristics If aluminum electrolytics are used their values should be 10 mF or larger The bypass capacitors should be mounted with the shortest leads and if possible directly across the regulator terminals High Stability 1 Amp Regulator TL H 7340 – 5 Load and line regulation k 0 01% temperature stability s 0 2% Determine Zener current Solid tantalum Select resistors to set output voltage 2 ppm C tracking suggested 4 Typical Applications (Continued) Current Source IOUT e 1 mA a 5V R1 TL H 7340 – 7 Light Controller Using Silicon Photo Cell TL H 7340 – 8 Lamp brightness increase until iI e iQ ( 1 mA) a 5V R1 Necessary only if raw supply filter capacitor is more than 2 from LM7905CT 5 Typical Applications (Continued) High-Sensitivity Light Controller TL H 7340 – 9 Lamp brightness increases until ii e 5V R1 (Ii can be set as low as 1 mA) Necessary only if raw supply filter capacitor is more than 2 from LM7905 g 15V 1 Amp Tracking Regulators TL H 7340 – 1 Load Regulation at DIL e 1A Output Ripple CIN e 3000 mF IL e 1A Temperature Stability Output Noise 10 Hz s f s 10 kHz ( b 15) 40 mV 100 mVrms 50 mV 150 mVrms ( a 15) 2 mV 100 mVrms 50 mV 150 mVrms Resistor tolerance of R4 and R5 determine matching of ( a ) and ( b ) outputs Necessary only if raw supply filter capacitors are more than 3 from regulators 6 b 5V 7 TL H 7340 – 12 Schematic Diagrams Schematic Diagrams (Continued) TL H 7340 – 13 b 12V and b 15V 8 9 LM79XX Series 3-Terminal Negative Regulators Physical Dimensions inches (millimeters) TO-220 Outline Package (T) Order Number LM7905CT LM7912CT or LM7915CT NS Package Number T03B 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 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 1111 West Bardin Road Arlington TX 76017 Tel 1(800) 272-9959 Fax 1(800) 737-7018 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 Europe Fax (a49) 0-180-530 85 86 Email cnjwge tevm2 nsc com Deutsch Tel (a49) 0-180-530 85 85 English Tel (a49) 0-180-532 78 32 Fran ais Tel (a49) 0-180-532 93 58 Italiano Tel (a49) 0-180-534 16 80 National Semiconductor Hong Kong Ltd 13th Floor Straight Block Ocean Centre 5 Canton Rd Tsimshatsui Kowloon Hong Kong Tel (852) 2737-1600 Fax (852) 2736-9960 National Semiconductor Japan Ltd Tel 81-043-299-2309 Fax 81-043-299-2408 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