LM341/LM78MXX Series 3-Terminal Positive Voltage Regulators General Description Features The LM341 and LM78MXX series of three-terminal positive voltage regulators employ built-in current limiting, thermal shutdown, and safe-operating area protection which makes them virtually immune to damage from output overloads. With adequate heatsinking, they can deliver in excess of 0.5A output current. Typical applications would include local (on-card) regulators which can eliminate the noise and degraded performance associated with single-point regulation. n n n n n n Output current in excess of 0.5A No external components Internal thermal overload protection Internal short circuit current-limiting Output transistor safe-area compensation Available in TO-220, TO-39, and TO-252 D-PAK packages n Output voltages of 5V, 12V, and 15V Connection Diagrams TO-39 Metal Can Package (H) DS010484-5 Bottom View Order Number LM78M05CH, LM78M12CH or LM78M15CH See NS Package Number H03A TO-220 Power Package (T) DS010484-6 Top View Order Number LM341T-5.0, LM341T-12, LM341T-15, LM78M05CT, LM78M12CT or LM78M15CT See NS Package Number T03B TO-252 DS010484-19 Top View Order Number LM78M05CDT See NS Package Number TD03B © 1999 National Semiconductor Corporation DS010484 www.national.com LM341/LM78MXX Series 3-Terminal Positive Voltage Regulators July 1999 Absolute Maximum Ratings (Note 1) Storage Temperature Range Operating Junction Temperature Range Power Dissipation (Note 2) Input Voltage 5V ≤ VO ≤ 15V ESD Susceptibility If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Lead Temperature (Soldering, 10 seconds) TO-39 Package (H) TO-220 Package (T) 300˚C 260˚C −65˚C to +150˚C −40˚C to +125˚C Internally Limited 35V TBD Electrical Characteristics Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the −40˚C to +125˚C operating temperature range. Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. LM341-5.0, LM78M05C Unless otherwise specified: VIN = 10V, CIN = 0.33 µF, CO = 0.1 µF Symbol VO VR LINE Parameter Output Voltage Line Regulation Min Typ Max Units IL = 500 mA Conditions 4.8 5.0 5.2 V 5 mA ≤ IL ≤ 500 mA 4.75 5.0 5.25 PD ≤ 7.5W, 7.5V ≤ VIN ≤ 20V IL = 100 mA IL = 500 mA 7.2V ≤ VIN ≤ 25V VR LOAD Load Regulation IQ Quiescent Current 5 mA ≤ IL ≤ 500 mA IL = 500 mA ∆IQ Quiescent Current Change 5 mA ≤ IL ≤ 500 mA Vn Output Noise Voltage 7.5V ≤ VIN ≤ 25V, IL = 500 mA f = 10 Hz to 100 kHz f = 120 Hz, IL = 500 mA Ripple Rejection VIN Input Voltage Required IL = 500 mA 50 mV 100 100 4 10.0 mA 0.5 1.0 40 µV 78 dB 7.2 V to Maintain Line Regulation ∆VO www.national.com Long Term Stability IL = 500 mA 20 2 mV/khrs Electrical Characteristics Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the −40˚C to +125˚C operating temperature range. Limits are guaranteed by production testing or correlation techniques using standard Statistical Quality Control (SQC) methods. (Continued) LM341-12, LM78M12C Unless otherwise specified: VIN = 19V, CIN = 0.33 µF, CO = 0.1 µF Symbol Parameter Output Voltage VO VR LINE Line Regulation Min Typ Max Units IL = 500 mA Conditions 11.5 12 12.5 V 5 mA ≤ IL ≤ 500 mA 11.4 12 12.6 PD ≤ 7.5W, 14.8V ≤ VIN ≤ 27V IL = 100 mA IL = 500 mA 14.5V ≤ VIN ≤ 30V VR LOAD Load Regulation IQ Quiescent Current 5 mA ≤ IL ≤ 500 mA IL = 500 mA ∆IQ Quiescent Current Change 5 mA ≤ IL ≤ 500 mA Vn Output Noise Voltage 14.8V ≤ VIN ≤ 30V, IL = 500 mA f = 10 Hz to 100 kHz f = 120 Hz, IL = 500 mA Ripple Rejection Input Voltage Required VIN IL = 500 mA 120 mV 240 240 4 10.0 mA 0.5 1.0 75 µV 71 dB 14.5 V to Maintain Line Regulation ∆VO Long Term Stability IL = 500 mA 48 mV/khrs LM341-15, LM78M15C Unless otherwise specified: VIN = 23V, CIN = 0.33 µF, CO = 0.1 µF Symbol Parameter Output Voltage VO VR LINE Line Regulation Min Typ Max Units IL = 500 mA Conditions 14.4 15 15.6 V 5 mA ≤ IL ≤ 500 mA 14.25 15 15.75 PD ≤ 7.5W, 18V ≤ VIN ≤ 30V 17.6V ≤ VIN ≤ 30V IL = 100 mA IL = 500 mA VR LOAD Load Regulation IQ Quiescent Current 5 mA ≤ IL ≤ 500 mA IL = 500 mA ∆IQ Quiescent Current Change 5 mA ≤ IL ≤ 500 mA Vn Output Noise Voltage 18V ≤ VIN ≤ 30V, IL = 500 mA f = 10 Hz to 100 kHz Ripple Rejection f = 120 Hz, IL = 500 mA VIN Input Voltage Required IL = 500 mA 150 mV 300 300 4 10.0 mA 0.5 1.0 90 µV 69 dB 17.6 V to Maintain Line Regulation ∆VO Long Term Stability IL = 500 mA 60 mV/khrs Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its rated operating conditions. Note 2: The typical thermal resistance of the three package types is: T (TO-220) package: θ(JA) = 60 ˚C/W, θ(JC) = 5 ˚C/W H (TO-39) package: θ(JA) = 120 ˚C/W, θ(JC) = 18 ˚C/W DT (TO-252) package: θ(JA) = 92 ˚C/W, θ(JC) = 10 ˚C/W 3 www.national.com Schematic Diagram DS010484-1 www.national.com 4 Typical Performance Characteristics Peak Output Current Ripple Rejection DS010484-10 Ripple Rejection DS010484-11 Dropout Voltage DS010484-12 Output Voltage (Normalized to 1V at TJ = 25˚C) DS010484-13 Quiescent Current DS010484-15 DS010484-14 5 www.national.com Typical Performance Characteristics (Continued) Quiescent Current Output Impedance DS010484-16 Line Transient Response DS010484-17 Load Transient Response DS010484-7 DS010484-8 device junction flows through the die to the die attach pad, through the lead frame to the surrounding case material, to the printed circuit board, and eventually to the ambient environment. Below is a list of variables that may affect the thermal resistance and in turn the need for a heatsink. Design Considerations The LM78MXX/LM341XX fixed voltage regulator series has built-in thermal overload protection which prevents the device from being damaged due to excessive junction temperature. The regulators also contain internal short-circuit protection which limits the maximum output current, and safe-area protection for the pass transistor which reduces the short-circuit current as the voltage across the pass transistor is increased. Although the internal power dissipation is automatically limited, the maximum junction temperature of the device must be kept below +125˚C in order to meet data sheet specifications. An adequate heatsink should be provided to assure this limit is not exceeded under worst-case operating conditions (maximum input voltage and load current) if reliable performance is to be obtained). 1.0 Heatsink Considerations RθJC(Component Variables) RθCA(Application Variables) Mounting Pad Size, Material, & Location No. of Conduction Pins Placement of Mounting Pad Die Size PCB Size & Material Die Attach Material Traces Length & Width Molding Compound Size and Adjacent Heat Sources Material Volume of Air Air Flow Ambient Temperature Shape of Mounting Pad When an integrated circuit operates with appreciable current, its junction temperature is elevated. It is important to quantify its thermal limits in order to achieve acceptable performance and reliability. This limit is determined by summing the individual parts consisting of a series of temperature rises from the semiconductor junction to the operating environment. A one-dimension steady-state model of conduction heat transfer is demonstrated in The heat generated at the www.national.com Leadframe Size & Material 6 Design Considerations (Continued) DS010484-23 DS010484-24 FIGURE 1. Cross-sectional view of Integrated Circuit Mounted on a printed circuit board. Note that the case temperature is measured at the point where the leads contact with the mounting pad surface FIGURE 2. Power Dissipation Diagram The next parameter which must be calculated is the maximum allowable temperature rise, TR(max): θJA = TR (max)/PD The LM78MXX/LM341XX regulators have internal thermal shutdown to protect the device from over-heating. Under all possible operating conditions, the junction temperature of the LM78MXX/LM341XX must be within the range of 0˚C to 125˚C. A heatsink may be required depending on the maximum power dissipation and maximum ambient temperature of the application. To determine if a heatsink is needed, the power dissipated by the regulator, PD, must be calculated: IIN = IL + IG PD = (VIN−VOUT) IL + VINIG shows the voltages and currents which are present in the circuit. If the maximum allowable value for θJA˚C/w is found to be ≥60˚C/W for TO-220 package or ≥92˚C/W for TO-252 package, no heatsink is needed since the package alone will dissipate enough heat to satisfy these requirements. If the calculated value for θJA fall below these limits, a heatsink is required. As a design aid, Table 1 shows the value of the θJA of TO-252 for different heatsink area. The copper patterns that we used to measure these θJA are shown at the end of the Application Note Section. reflects the same test results as what are in the Table 1 shows the maximum allowable power dissipation vs. ambient temperature for theTO-252 device. shows the maximum allowable power dissipation vs. copper area (in2) for the TO-252 device. Please see AN1028 for power enhancement techniques to be used with TO-252 package. TABLE 1. θJA Different Heatsink Area Layout Copper Area Thermal Resistance Top Sice (in2)* Bottom Side (in2) (θJA, ˚C/W) TO-252 1 0.0123 0 103 2 0.066 0 87 3 0.3 0 60 4 0.53 0 54 5 0.76 0 52 6 1 0 47 7 0 0.2 84 8 0 0.4 70 9 0 0.6 63 10 0 0.8 57 11 0 1 57 12 0.066 0.066 89 13 0.175 0.175 72 14 0.284 0.284 61 15 0.392 0.392 55 16 0.5 0.5 53 *Tab of device attached to topside copper 7 www.national.com Design Considerations (Continued) DS010484-21 FIGURE 5. Maximum Allowable Power Dissipation vs. 2oz. Copper Area for TO-252 DS010484-20 FIGURE 3. θJA vs. 2oz Copper Area for TO-252 Typical Application DS010484-9 DS010484-22 *Required if regulator input is more than 4 inches from input filter capacitor (or if no input filter capacitor is used). **Optional for improved transient response. FIGURE 4. Maximum Allowable Power Dissipation vs. Ambient Temperature for TO-252 www.national.com 8 Physical Dimensions inches (millimeters) unless otherwise noted TO-39 Metal Can Package (H) Order Number LM78M05CH, LM78M12CH or LM78M15CH NS Package Number H03A 9 www.national.com Physical Dimensions inches (millimeters) unless otherwise noted (Continued) TO-220 Power Package (T) Order Number LM341T-5.0, LM341T-12, LM341T-15, LM78M05CT, LM78M12CT or LM78M15CT NS Package Number T03B www.national.com 10 LM341/LM78MXX Series 3-Terminal Positive Voltage Regulators Physical Dimensions inches (millimeters) unless otherwise noted (Continued) TO-252 Order Number LM78M05CDT NS Package Number TD03B 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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