tl/h/10483 LM79Mxx series 3-terminal negative regulators december 1994 LM79Mxx series 3-terminal negative regulators general description the LM79Mxx series of 3-terminal regulators is available with fixed output voltages of b 5v, b 12v, and b 15v. these devices need only one external componentea compensa- tion capacitor at the output. the LM79Mxx series is pack- aged in the to-220 power package, and is capable of sup- plying 0.5a of output current. these regulators employ internal current limiting, safe area protection, and thermal shotdown for protection against vir- tually all overload conditions. low ground pin current of the LM79Mxx series allows out- put voltage to be easily boosted above the preset value with a resistor divider. the low quiescent current of these devic- es with a specified maximum change with line and load en- sures good regulation in the voltage boosted mode. for output voltage other than b 5v, b 12v, and b 15v the lm137 series provides an output voltage range from b 1.2v to b 57v. features y thermal, short circuit and safe area protection y high ripple rejection y 0.5a output current y 4% tolerance on preset output voltage connection diagram to-220 plastic package (t) tl/h/10483 7 front view order number LM79M05ct, LM79M12ct or LM79M15ct see ns package number t03b c 1995 national semiconductor corporation 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 v o eb 5v b 25v v o eb 12v, b 15v b 35v input/output differential v o eb 5v 25v v o eb 12v, b 15v 30v power dissipation (note 2) internally limited operating junction temperature range 0 cto a 125 c storage temperature range b 65 cto a 150 c lead temperature (soldering, 10 sec.) 230 c esd susceptability tbd electrical characteristics LM79M05c conditions unless otherwise noted: i out e 350 ma, c in e 2.2 m f, c out e 1 m f, 0 c s t j s a 125 c part number LM79M05c output voltage b 5v units input voltage (unless otherwise specified) b 10v symbol parameter conditions min typ max v o output voltage t j e 25 c b 4.8 b 5.0 b 5.2 v 5ma s i out s 350 ma b 4.75 b 5.25 v ( b 25 s v in s b 7) d v o line regulation t j e 25 c (note 3) 8 50 mv ( b 25 s v in s b 7) 230mv ( b 18 s v in s b 8) d v o load regulation t j e 25 c, (note 3) 30 100 mv 5ma s i out s 0.5a i q quiescent current t j e 25 c12ma d i q quiescent current with input voltage 0.4 ma change ( b 25 s v in s b 8) with load, 5ma s i out s 350 ma 0.4 ma v n output noise voltage t a e 25 c, 150 m v 10 hz s f s 100 hz ripple rejection f e 120 hz 54 66 db ( b 18 s v in s b 8) dropout voltage t j e 25 c, i out e 0.5a 1.1 v i omax peak output current t j e 25 c 800 ma average temperature i out e 5 ma, coefficient of 0 c s t j s 100 c b 0.4 mv/ c output voltage 2
electrical characteristics LM79M12c, LM79M15c conditions unless otherwise noted: i out e 350 ma, c in e 2.2 m f, c out e 1 m f, 0 c s t j s a 125 c part number LM79M12c LM79M15c output voltage b 12v b 15v units input voltage (unless otherwise specified) b 19v b 23v symbol parameter conditions min typ max min typ max v o output voltage t j e 25 c b 11.5 b 12.0 b 12.5 b 14.4 b 15.0 b 15.6 v 5ma s i out s 350 ma b 11.4 b 12.6 b 14.25 b 15.75 v ( b 27 s v in s b 14.5) ( b 30 s v in s b 10.5) d v o line regulation t j e 25 c (note 3) 5 80 5 80 mv ( b 30 s v in s b 14.5) ( b 30 s v in s b 17.5) 3 50 3 50 mv ( b 25 s v in s b 15) ( b 28 s v in s b 18) d v o load regulation t j e 25 c, (note 3) 30 240 30 240 mv 5ma s i out s 0.5a i q quiescent current t j e 25 c 1.5 3 1.5 3 ma d i q quiescent current with input voltage 0.4 0.4 ma change ( b 30 s v in s b 14.5) ( b 30 s v in s b 27) with load, 5ma s i out s 350 ma 0.4 0.4 ma v n output noise voltage t a e 25 c, 400 400 m v 10 hz s f s 100 hz ripple rejection f e 120 hz 54 70 54 70 db ( b 25 s v in s b 15) ( b 30 s v in s b 17.5) dropout voltage t j e 25 c, i out e 0.5a 1.1 1.1 v i omax peak output current t j e 25 c 800 800 ma average temperature i out e 5 ma, coefficient of 0 c s t j s 100 c b 0.8 b 1.0 mv/ 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. 3
typical performance characteristics temperature output voltage vs ripple rejection output impedance differential minimum input-output input voltage quiescent current vs load current quiescent current vs short-circuit current dissipation (to-220) maximum average power tl/h/10483 10 4
schematic diagrams b 5v tl/h/10483 8 b 12v and b 15v tl/h/10483 9 5
design considerations the LM79Mxx fixed voltage regulator series have thermal- overload protection from excessive power, internal short-cir- cuit 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 junc- tion temperature must be kept below the maximum speci- fied 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: package i jc i ja ( c/w) ( c/w) to-220 3 40 p dmax e t jmax b t a i jc a i ca or (1) e t jmax b t a i ja (without a heat sink) i ca e i cs a i sa solving for t j : t j e t a a p d ( i jc a i ca )or e t a ea p d i ja (without a heat sink) where t j e junction temperature t a e ambient temperature p d e power dissipation i jc e junction-to-case thermal resistance i ca e case-to-ambient thermal resistance i cs e case-to-heat sink thermal resistance i sa e heat sink-to-ambient thermal resistance i ja e junction-to-ambient thermal resistance typical applications 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 im- prove the transient response of the regulator. the bypass capacitors (2.2 m f on the input, 1.0 m fonthe output), should be ceramic or solid tantalum which have good high frequency characteristics. if aluminum electrolyt- ics are used, their values should be 10 m f or larger. the bypass capacitors should be mounted with the shortest leads, and if possible, directly across the regulator termi- nals. fixed regulator tl/h/10483 2 * required if regulator is separated from filter capacitor by more than 3 . for value given, capacitor must be solid tantalum. 25 m f aluminum elec- trolytic may be substituted. 2 required for stability. for value given, capacitor must be solid tantalum. 25 m f aluminum electrolytic may be substituted. values given may be increased without limit. for output capacitance in excess of 100 m f, a high current diode from input to output (1n4001, etc.) will protect the regulator from momentary input shorts. variable output tl/h/10483 3 * improves transient response and ripple rejection. do not increase beyond 50 m f. v out e v set # r1 a r2 r2 j select r2 as follows: LM79M05c 300 x LM79M12c 750 x LM79M15c 1k 6
typical applications (continued) g 15v, 1 amp tracking regulators tl/h/10483 1 performance (typical) ( b 15) ( a 15) load regulation at 0.5a 40 mv 2 mv output ripple, c in e 3000 m f, i l e 0.5a 100 m vrms 100 m vrms temperature stability 50 mv 50 mv output noise 10 hz s f s 10 khz 150 m vrms 150 m vrms * 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. dual trimmed supply tl/h/10483 4 7
LM79Mxx series 3-terminal negative regulators physical dimensions inches (millimeters) 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 of national semiconductor corporation. as used herein: 1. life support devices or systems are devices or 2. a critical component is any component of a life systems which, (a) are intended for surgical implant support device or system whose failure to perform can into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life failure to perform, when properly used in accordance support device or system, or to affect its safety or with instructions for use provided in the labeling, can effectiveness. be reasonably expected to result in a significant injury to the user. national semiconductor national semiconductor national semiconductor national semiconductor corporation europe hong kong ltd. japan ltd. 1111 west bardin road fax: ( a 49) 0-180-530 85 86 13th floor, straight block, tel: 81-043-299-2309 arlington, tx 76017 email: cnjwge @ tevm2.nsc.com ocean centre, 5 canton rd. fax: 81-043-299-2408 tel: 1(800) 272-9959 deutsch tel: ( a 49) 0-180-530 85 85 tsimshatsui, kowloon fax: 1(800) 737-7018 english tel: ( a 49) 0-180-532 78 32 hong kong fran 3 ais tel: ( a 49) 0-180-532 93 58 tel: (852) 2737-1600 italiano tel: ( a 49) 0-180-534 16 80 fax: (852) 2736-9960 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.
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