LM79XX Series 3-Terminal Negative Regulators General Description The LM79XX series of 3-terminal regulators is available with fixed output voltages of -5V, -12V, and -15V. 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 Connection Diagrams 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 datasheet. Features n n n n 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 DS007340-3 DS007340-14 Front View Order Number LM7905CT, LM7912CT or LM7915CT See NS Package Number TO3B (c) 2001 National Semiconductor Corporation DS007340 *Required if regulator is separated from filter capacitor by more than 3". For value given, capacitor must be solid tantalum. 25F aluminum electrolytic may be substituted. Required for stability. For value given, capacitor must be solid tantalum. 25F aluminum electrolytic may be substituted. Values given may be increased without limit. For output capacitance in excess of 100F, a high current diode from input to output (1N4001, etc.) will protect the regulator from momentary input shorts. www.national.com LM79XX Series 3-Terminal Negative Regulators September 2001 LM79XX Series Absolute Maximum Ratings (Note 1) Input-Output Differential (Vo = -5V) (Vo = -12V and -15V) Power Dissipation (Note 2) Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 sec.) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Voltage (Vo = -5V) (Vo = -12V and -15V) -25V -35V 25V 30V Internally Limited 0C to +125C -65C to +150C 230C Electrical Characteristics Conditions unless otherwise noted: IOUT = 500mA, CIN = 2.2F, COUT = 1F, 0C TJ +125C, Power Dissipation 1.5W. Part Number LM7905C Output Voltage -5V Input Voltage (unless otherwise specified) Symbol VO Parameter Output Voltage -10V Conditions Min Typ Max TJ = 25C -4.8 -5.0 -5.2 V 5mA IOUT 1A, -4.75 -5.25 V 50 mV 15 mV P 15W VO Line Regulation Units (-20 VIN -7) TJ = 25C, (Note 3) V 8 (-25 VIN -7) V 2 (-12 VIN -8) VO Load Regulation V TJ = 25C, (Note 3) 5mA IOUT 1.5A 15 100 mV 250mA IOUT 750mA 5 50 mV IQ Quiescent Current TJ = 25C 1 2 mA IQ Quiescent Current With Line 0.5 mA 0.5 mA (-25 VIN -7) Change V With Load, 5mA IOUT 1A Vn IOMAX Output Noise Voltage TA = 25C, 10Hz f 100Hz Ripple Rejection f = 120Hz (-18 VIN -8) V Dropout Voltage TJ = 25C, IOUT = 1A 1.1 V Peak Output Current TJ = 25C 2.2 A Average Temperature IOUT = 5mA, 0.4 mV/C Coefficient of 0 C TJ 100C 54 125 V 66 dB Output Voltage Electrical Characteristics Conditions unless otherwise noted: IOUT = 500mA, CIN = 2.2F, COUT = 1F, 0C TJ +125C, Power Dissipation 1.5W. Part Number LM7912C LM7915C Output Voltage -12V -15V Input Voltage (unless otherwise specified) Symbol VO Parameter Output Voltage -19V Conditions Min Line Regulation -23V Max TJ = 25C -11.5 -12.0 -12.5 5mA IOUT 1A, -11.4 P 15W VO Typ -12.6 (-27 VIN -14.5) TJ = 25C, (Note 3) 5 80 Load Regulation www.national.com TJ = 25C, (Note 3) 2 Min Typ -14.4 -15.0 -14.25 Max -15.6 V -15.75 V (-30 VIN -17.5) V 5 mV 100 (-30 VIN -14.5) (-30 VIN -17.5) V 3 3 mV 30 (-22 VIN -16) VO Units 50 (-26 VIN -20) V (Continued) Conditions unless otherwise noted: IOUT = 500mA, CIN = 2.2F, COUT = 1F, 0C TJ +125C, Power Dissipation 1.5W. Part Number LM7912C LM7915C Output Voltage -12V -15V Input Voltage (unless otherwise specified) Symbol Parameter -19V Conditions Max 5mA IOUT 1.5A 15 250mA IOUT 750mA 5 1.5 Quiescent Current TJ = 25C IQ Quiescent Current With Line Min Max 200 15 200 75 5 75 mV 3 1.5 3 mA 0.5 mA 0.5 With Load, 5mA IOUT 1A IOMAX Typ (-30 VIN -14.5) Change Vn -23V Typ IQ Min Output Noise Voltage TA = 25C, 10Hz f 100Hz Ripple Rejection f = 120 Hz (-30 VIN -17.5) 0.5 0.5 300 54 Units 70 54 mV V mA 375 V 70 dB (-25 VIN -15) (-30 VIN -17.5) V 1.1 1.1 V Dropout Voltage TJ = 25C, IOUT = 1A Peak Output Current TJ = 25C 2.2 2.2 A Average Temperature IOUT = 5mA, -0.8 -1.0 mV/C Coefficient of 0 C TJ 100C 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. Design Considerations JA JC 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 (125C) 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 Max Typ Max JC JC JA JA C/W C/W C/W C/W 3.0 5.0 60 40 = Junction-to-Ambient Thermal Resistance = Junction-to-Case Thermal Resistance CA = Case-to-Ambient Thermal Resistance CS = Case-to-Heat Sink Thermal Resistance SA = Heat Sink-to-Ambient Thermal Resistance Solving for TJ: TJ = TA + PD (JC + CA) or = TA + PDJA (without heat sink) Where: TJ = Junction Temperature TA = Ambient Temperature PD = Power Dissipation 3 www.national.com LM79XX Series Electrical Characteristics LM79XX Series Typical Applications high frequency characteristics. If aluminum electrolytics are used, their values should be 10F or larger. The bypass capacitors should be mounted with the shortest leads, and if possible, directly across the regulator terminals. 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, (2.2F on the input, 1.0F on the output) should be ceramic or solid tantalum which have good High Stability 1 Amp Regulator DS007340-5 Load and line regulation < 0.01% temperature stability 0.2% Determine Zener current Solid tantalum *Select resistors to set output voltage. 2 ppm/C tracking suggested Current Source DS007340-7 www.national.com 4 LM79XX Series Typical Applications (Continued) Light Controller Using Silicon Photo Cell DS007340-8 *Lamp brightness increase until iI = iQ ( 1 mA) + 5V/R1. Necessary only if raw supply filter capacitor is more that 2" from LM7905CT High-Sensitivity Light Controller DS007340-9 *Lamp brightness increases until ii = 5V/R1 (Ii can be set as low as 1 A) Necessary only if raw supply filter capacitor is more that 2" from LM7905 Variable Output DS007340-2 *Improves transient response and ripple rejection. Do not increase beyond 50 F. Select R2 as follows: LM7905CT 300 LM7912CT 750 LM7915CT 1k 5 www.national.com LM79XX Series Typical Applications (Continued) 15V, 1 Amp Tracking Regulators DS007340-1 (-15) (+15) Load Regulation at IL = 1A 40mV 2mV Output Ripple, CIN = 3000F, IL = 1A 100 Vms 100 Vms Temperature Stability 50mV 50mV Output Noise 10Hz f 10kHz 150 Vms 150 Vms *Resistor tolerance of R4 and R5 determine matching of (+) and (-) outputs. **Necessary only if raw supply filter capacitors are more than 3" from regulators. Dual Trimmed Supply DS007340-4 www.national.com 6 LM79XX Series -5V DS007340-12 Schematic Diagrams 7 www.national.com DS007340-13 (Continued) -12V and -15V LM79XX Series Schematic Diagrams www.national.com 8 LM79XX Series 3-Terminal Negative Regulators Physical Dimensions inches (millimeters) unless otherwise noted 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 AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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