LM79MXX Series 3-Terminal Negative Regulators General Description The LM79MXX 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 LM79MXX series is packaged in the TO-220 power package, and is capable of supplying 0.5A 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 LM79MXX series allows output voltage to be easily boosted above the preset value with a resistor divider. The low quiescent current of these devices with a specified maximum change with line and load ensures good regulation in the voltage boosted mode. For output voltage other than −5V, −12V, and −15V the LM137 series provides an output voltage range from −1.2V to −57V. Features n n n n Thermal, short circuit and safe area protection High ripple rejection 0.5A output current 4% tolerance on preset output voltage Connection Diagram TO-220 Plastic Package (T) DS010483-7 Front View Order Number LM79M05CT, LM79M12CT or LM79M15CT See NS Package Number T03B © 2001 National Semiconductor Corporation DS010483 www.national.com LM79MXX Series 3-Terminal Negative Regulators September 2001 LM79MXX Series 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 = −5V VO = −12V, −15V Input/Output Differential VO = −5V VO = −12V, −15V Power Dissipation (Note 2) Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 sec.) ESD Susceptibility −25V −35V 25V 30V Internally Limited 0˚C to +125˚C −65˚C to +150˚C 230˚C TBD Electrical Characteristics LM79M05C Conditions unless otherwise noted: IOUT = 350mA, CIN = 2.2µF, COUT = 1µF, 0˚C ≤ TJ ≤ +125˚C Part Number LM79M05C Output Voltage −5V Input Voltage (Unless Otherwise Specified) −10V Symbol VO Parameter Output Voltage Conditions Min Typ TJ = 25˚C −4.8 −5.0 5mA ≤ IOUT ≤ 350mA −4.75 Units Max −5.2 V −5.25 V 50 mV 30 mV 30 100 mV 1 2 mA 0.4 mA 0.4 mA (−25 ≤ VIN ≤ −7) ∆VO Line Regulation TJ = 25˚C (Note 3) 8 (−25 ≤ VIN ≤ −7) 2 (−18 ≤ VIN ≤ − 8) ∆VO Load Regulation TJ = 25˚C, (Note 3) 5mA ≤ IOUT ≤ 0.5A IQ Quiescent Current TJ = 25˚C ∆IQ Quiescent Current With Input Voltage (−25 ≤ VIN ≤ −8) Change With Load, 5mA ≤ IOUT ≤ 350mA Vn Output Noise Voltage TA = 25˚C, 150 µV 66 dB 10Hz ≤ f ≤ 100Hz Ripple Rejection f = 120Hz 54 Dropout Voltage TJ = 25˚C, IOUT = 0.5A 1.1 V Peak Output Current TJ = 25˚C 800 mA Average Temperature IOUT = 5mA, Coefficient of 0˚C ≤ TJ ≤ 100˚C −0.4 mV/˚C (−18 ≤ VIN ≤ −8) IOMAX Output Voltage www.national.com 2 Part Number LM79M12C LM79M15C Output Voltage −12V −15V Input Voltage (Unless Otherwise Specified) −19V −23V Symbol VO ∆VO Parameter Output Voltage Line Regulation Conditions Min Typ Max Min Typ TJ = 25˚C −11.5 −12.0 5 mA ≤ IOUT ≤ 350mA −11.4 −12.5 −14.4 −15.0 −12.6 −14.25 −15.6 V −15.75 V (−30 ≤ VIN ≤ −10.5) 5 5 TJ = 25˚C (Note 3) 80 3 Load Regulation Max (−27 ≤ VIN ≤ −14.5) (−30 ≤ VIN ≤ −14.5) ∆VO Units TJ = 25˚C, (Note 3) 80 mV (−30 ≤ VIN ≤−17.5) 50 3 50 mV 240 mV (−25 ≤ VIN ≤ − 15) (−28 ≤ VIN ≤ −18) 30 240 30 3 1.5 5mA ≤ IOUT ≤ 0.5A IQ Quiescent Current TJ = 25˚C ∆IQ Quiescent Current With Input Voltage 1.5 0.4 (−30 ≤ VIN ≤ −14.5) Change 3 mA 0.4 mA 0.4 mA (−30 ≤ VIN ≤ −27) With Load, 5mA ≤ IOUT ≤ 350mA Vn Output Noise Voltage Ripple Rejection 0.4 TA = 25˚C, 400 f = 120Hz 54 70 (−25 ≤ VIN ≤ −15) IOMAX 400 µV 70 dB 10Hz ≤ f ≤ 100Hz 54 (−30 ≤ VIN ≤ −17.5) Dropout Voltage TJ = 25˚C, IOUT = 0.5A 1.1 1.1 V Peak Output Current TJ = 25˚C 800 800 mA −0.8 −1.0 mV/˚C Average Temperature IOUT = 5mA, Coefficient of 0˚C ≤ TJ ≤ 100˚C 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 measued 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 Performance Characteristics Output Voltage vs. Temperature Ripple Rejection DS010483-11 DS010483-12 3 www.national.com LM79MXX Series Electrical Characteristics LM79M12C, LM79M15C Conditions unless otherwise noted: IOUT = 350mA, CIN = 2.2µF, COUT = 1 µF, 0˚C ≤ TJ ≤ +125˚C LM79MXX Series Typical Performance Characteristics (Continued) Output Impedance Minimum Input-Output Differential DS010483-13 DS010483-14 Quiescent Current vs. Input Voltage Quiescent Current vs. Load Current DS010483-16 DS010483-15 Short-Circuit Current Maximum Average Power Dissipation (TO-220) DS010483-17 DS010483-18 www.national.com 4 LM79MXX Series Schematic Diagrams −5V DS010483-8 −12V and −15V DS010483-9 5 www.national.com LM79MXX Series Design Considerations Typical Applications The LM79MXX fixed voltage regulator series have thermal-overload protection from excessive power, 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 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: Bypass capacitors are necessary for stable operation of the LM79MXX series of regulators over the input voltage and output current ranges. Output bypass capacitors will improve the transient response of the regulator. Package θJC θJA (˚C/W) (˚C/W) 3 40 TO-220 The bypass capacitors (2.2µF on the input, 1.0µF on the output), should be ceramic or solid tantalum which have good high frequency characteristics. If aluminum electrolytics are used, their values should be 10µF or larger. The bypass capacitors should be mounted with the shortest leads, and if possible, directly across the regulator terminals. Fixed Regulator DS010483-2 *Required if regulator is separated from filter capacitor by more than 3". For value given, capacitor must be solid tantalum. 25µF aluminum electrolytic may be substituted. †Required for stability. For value given, capacitor must be solid tantalum. 25µF aluminum electrolytic may be substituted. Values given may be increased without limit. For output capacitance in excess of 100µF, a high current diode from input to output (1N4001, etc.) will protect the regulator from momentary input shorts. (1) θCA = θCS+θSA Solving for TJ: TJ = TA+ PD (θJC+θCA) or = TA =+ PDθJA(Without a Heat Sink) Where TJ = Junction Temperature TA = Ambient Temperature PD = Power Dissipation θJC = Junction-to-Case Thermal Resistance θCA = Case-to-Ambient Thermal Resistance θCS = Case-to-Heat Sink Thermal Resistance θSA = Heat Sink-to-Ambient Thermal Resistance θJA = Junction-to-Ambient Thermal Resistance Variable Output DS010483-3 *Improves transient response and ripple rejection. Do not increase beyond 50µF. Select R2 as follows: LM79M05C 300Ω LM79M12C 750Ω LM79M15C 1k www.national.com 6 LM79MXX Series Typical Applications (Continued) ± 15V, 1 Amp Tracking Regulators DS010483-1 *Resistor tolerance of R4 and R5 determine matching of (+) and (−) outputs. **Necessary only if raw supply filter capacitors are more than 3" from regulators. Performance (Typical) (−15) (+15) 40mV 2 mV 100 µVrms 100 µVrms Load Regulation at 0.5A Output Ripple, CIN = 3000µF, IL = 0.5A Temperature Stability Output Noise 10Hz ≤ f ≤ 10kHz 50mV 50mV 150 µVrms 150 µVrms Dual Trimmed Supply DS010483-4 7 www.national.com LM79MXX Series 3-Terminal Negative Regulators Physical Dimensions inches (millimeters) unless otherwise noted TO-220 Plastic Package (T) Order Number LM79M05CT, LM79M12CT or LM79M15CT 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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