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 componentÐa 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 Connection Diagrams 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 Typical Applications TO-220 Package Fixed Regulator Front View *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. TL/H/7340 – 3 TL/H/7340 – 14 Order Number LM7905CT, LM7912CT or LM7915CT See NS Package Number TO3B C1995 National Semiconductor Corporation TL/H/7340 ² 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. RRD-B30M115/Printed in U. S. A. LM79XX Series 3-Terminal Negative Regulators November 1994 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-Output Differential (Vo e b5V) (Vo e b12V and b15V) Input Voltage (Vo e b5V) (Vo e b12V and b15V) 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 b 25V b 35V 25V 30V 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 b 5V Input Voltage (unless otherwise specified) b 10V Symbol VO DVO DVO LM7905C Parameter Conditions Output Voltage TJ e 25§ C 5 mA s IOUT s 1A, P s 15W Line Regulation TJ e 25§ C, (Note 3) Load Regulation Min Typ Max b 4.8 b 4.75 b 5.0 b 5.2 b 5.25 V V V 50 mV V mV V (b20 s VIN s b7) 8 (b25 s VIN s b7) 2 (b12 s VIN s b8) TJ e 25§ C, (Note 3) 5 mA s IOUT s 1.5A 250 mA s IOUT s 750 mA 15 5 1 IQ Quiescent Current TJ e 25§ C DIQ Quiescent Current Change With Line IOMAX 15 100 50 mV mV 2 mA 0.5 mA V mA (b25 s VIN s b7) With Load, 5 mA s IOUT s 1A Vn Units 0.5 Output Noise Voltage TA e 25§ C, 10 Hz s f s 100 Hz Ripple Rejection f e 120 Hz Dropout Voltage TJ e 25§ C, IOUT e 1A 1.1 V Peak Output Current TJ e 25§ C 2.2 A Average Temperature Coefficient of Output Voltage IOUT e 5 mA, 0 C s TJ s 100§ C 0.4 mV/§ C 54 125 mV 66 (b18 s VIN s b8) dB V 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. Symbol Part Number LM7912C LM7915C Output Voltage b 12V b 15V Input Voltage (unless otherwise specified) b 19V b 23V Parameter Conditions Min Typ Max Min Typ Units Max VO Output Voltage TJ e 25§ C 5 mA s IOUT s 1A, P s 15W 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) V V V DVO Line Regulation TJ e 25§ C, (Note 3) 5 80 (b30 s VIN s b14.5) 3 30 (b22 s VIN s b16) 5 100 (b30 s VINs b17.5) 3 50 (b26 s VIN s b20) mV V mV V DVO Load Regulation TJ e 25§ C, (Note 3) 5 mA s IOUT s 1.5A 250 mA s IOUT s 750 mA 15 5 200 75 15 5 200 75 mV mV 3 1.5 3 mA IQ Quiescent Current TJ e 25§ C 1.5 DIQ Quiescent Current Change With Line 0.5 (b30 s VIN s b14.5) 0.5 With Load, 5 mA s IOUT s 1A Vn IOMAX Output Noise Voltage TA e 25§ C, 10 Hz s f s 100 Hz Ripple Rejection f e 120 Hz Dropout Voltage Peak Output Current Average Temperature Coefficient of Output Voltage IOUT e 5 mA, 0 C s TJ s 100§ C 0.5 (b30 sVIN s b17.5) 0.5 mA V mA 300 375 mV 54 70 (b25 s VIN s b15) 54 70 (b30 s VINs b17.5) dB V TJ e 25§ C, IOUT e 1A 1.1 1.1 V TJ e 25§ C 2.2 2.2 A b 0.8 b 1.0 mV/§ C 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 Where: 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: Package TO-220 Typ iJC § C/W Max iJC § C/W Typ iJA § C/W Max iJA § C/W 3.0 5.0 60 40 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 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. TJ Max b TA TJ Max TA PD MAX e or iJC a iCA iJA e a iCA iCS iSA (without heat sink) Solving for TJ: TJ e TA a PD (iJC a iCA) or e TA a PDiJA (without heat sink) High Stability 1 Amp Regulator TL/H/7340 – 5 Load and line regulation k 0.01% temperature stability s 0.2% ² Determine Zener current ² ² 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. ² 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) ² 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 TL/H/7340 – 12 Schematic Diagrams 7 b 12V and b 15V TL/H/7340 – 13 Schematic Diagrams (Continued) 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. 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