? semiconductor components industries, llc, 2004 march, 2004 ? rev. 5 1 publication order number: MC34268/d MC34268 800 ma, 2.85 v, scsi-2 active terminator, low dropout voltage regulator the MC34268 is a medium current, low dropout positive voltage regulator specifically designed for use in scsi?2 active termination circuits. this device offers the circuit designer an economical solution for precision voltage regulation, while keeping power losses to a minimum. the regulator consists of a 1.0 v dropout composite pnp/npn pass transistor, current limiting, and thermal limiting. these devices are packaged in the soic?8 and dpak?3 and sot?223 surface mount power packages. applications include active scsi?2 terminators and post regulation of switching power supplies. features ? 2.85 v output voltage for scsi?2 active termination ? 1.0 v dropout ? output current in excess of 800 ma ? thermal protection ? short circuit protection ? output trimmed to 1.4% tolerance ? no minimum load required ? space saving dpak?3, sot?223 and soic?8 surface mount power packages ? pb?free packages are available simplified block diagram input thermal limiting control circuit current limit output ground see detailed ordering and shipping information in the package dimensions section on page 3 of this data sheet. ordering information 8 1 8 7 6 5 1 2 3 4 gnd soic?8 d suffix case 751 dpak?3 dt suffix case 369a input nc nc 123 (top view) (top view) 1 3 output output heatsink surface (shown as terminal 4 in case outline drawing) is connected to pin 2. sot?223 st suffix case 318e 1 3 pin 1. ground 2. output 3. input 4. output 4 marking diagrams alyw 34268 1 8 34268 alyww ayw 268st a = assembly location l = wafer lot y = year w = work week http://onsemi.com
MC34268 http://onsemi.com 2 maximum ratings rating symbol value unit power supply input voltage v in 15 v power dissipation and thermal characteristics dt suffix, plastic package, case 369a t a = 25 c, derate above t a = 25 c thermal resistance, junction?to?case thermal resistance, junction?to?air d suffix, plastic package, case 751 t a = 25 c, derate above t a = 25 c thermal resistance, junction?to?case thermal resistance, junction?to?air st suffix, plastic package, case 318e t a = 25 c, derate above t a = 25 c thermal resistance, junction?to?case thermal resistance, junction?to?air p d r jc r ja p d r jc r ja p d r jc r ja internally limited 5.0 87 internally limited 22 140 internally limited 15 245 w c/w c/w w c/w c/w w c/w c/w operating ambient temperature range t a 0 to +125 c maximum die junction t emperature t j +150 c storage t emperature t stg ? 55 to +150 c electrical characteristics (v in = 4.25 v, c o = 10 f, for typical values t a = 25 c, for min/max values t a = 0 c to +125 c, unless otherwise noted.) characteristic symbol min typ max unit output voltage (t a = 25 c, i o = 0 ma) output voltage, over line, load, and temperature (v in = 3.9 v to 15 v, i o = 0 ma to 490 ma) v o 2.81 2.76 2.85 2.85 2.89 2.93 v line regulation (v in = 4.25 v to 15 v, i o = 0 ma, t a = 25 c) reg line ? ? 0.3 % load regulation (i o = 0 ma to 800 ma, t a = 25 c) reg load ? ? 0.5 % dropout voltage (i o = 490 ma) v in ?v o ? 0.95 1.1 v ripple rejection (f = 120 hz) rr 55 ? ? db maximum output current (v in = 5.0 v) i (max) 800 ? ? ma bias current (v in = 4.25 v, i o = 0 ma) i b ? 5.0 to 3.0 8.0 ma minimum load current to maintain regulation (v in = 15 v) i l(min) ? ? 0 ma i o , output load current (ma) in v o -v figure 1. dropout voltage versus output load current 1.5 1.3 1.1 0.9 0.7 0.5 0 200 400 600 800 1000 figure 2. transient load regulation , dr o p o ut v o lta g e (v) t j = 25 c 20 ms/div v in = 5.0 v c o = 10 f t a = 25 c , output current i o v o , output voltage deviation d
MC34268 http://onsemi.com 3 figure 3. typical scsi application 1n5819 to scsi bus MC34268 scsi regulator 110 10 10 5.0v v in v o gn d c o figure 3 is a circuit of a typical scsi terminator application. the MC34268 is designed specifically to provide 2.85 v required to drive a scsi?2 bus. the output current capability of the regulator is in excess of 800 ma; enough to drive standard scsi?2, fast scsi?2, and some wide scsi?2 applications. the typical dropout voltage is less than 1.0 v, allowing the ic to regulate to input voltages less than 4.0 v. internal protective features include current and thermal limiting. the MC34268 requires an external 10 f capacitor with an esr of less than 10 for stability over temperature. with economical electrolytic capacitors, cold temperature operation can pose a stability problem. as temperature decreases, the capacitance also decreases and the esr increases, which could cause the circuit to oscillate. tantalum capacitors may be a better choice if small size is a requirement. also, the capacitance and esr of a tantalum capacitor is more stable over temperature. , thermal resistance junction-to-air ( c/w) figure 4. soic?8 thermal resistance versus p.c.b. copper length 0 10203040 l, length of copper (mm) figure 5. dpak?3 thermal resistance versus p.c.b. copper length 0 102030405060 l, length of copper flags (mm) q ja , thermal resistance junction-to-air ( c/w) q ja 70 90 80 70 60 50 40 180 160 120 80 40 0 l l 2.0 oz copper l 9.0 mm p.c. board heatsink example l l 2.0 oz copper p.c. board heatsink example ordering information device package shipping information 2 MC34268d soic?8 98 units / rail MC34268dg soic?8 (pb?free) 98 units / rail MC34268dr2 soic?8 2500 units / tape & reel MC34268dt dpak?3 75 units / rail MC34268dtrk dpak?3 2500 units / tape & reel MC34268stt3 sot?223 4000 units / tape & reel 2for information on tape and reel specifications, including part orientation and tape sizes, please refer to our tape and reel packaging specifications brochure, brd8011/d.
MC34268 http://onsemi.com 4 package dimensions soic?8 d suffix case 751?07 issue ab soic?8 1.52 0.060 7.0 0.275 0.6 0.024 1.270 0.050 4.0 0.155 mm inches scale 6:1 *for additional information on our pb?free strategy and soldering details, please download the on semiconductor soldering and mounting techniques reference manual, solderrm/d. soldering footprint* seating plane 1 4 5 8 n j x 45 k notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimension a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006) per side. 5. dimension d does not include dambar protrusion. allowable dambar protrusion shall be 0.127 (0.005) total in excess of the d dimension at maximum material condition. 6. 751-01 thru 751-06 are obsolete. new standard is 751-07. a b s d h c 0.10 (0.004) dim a min max min max inches 4.80 5.00 0.189 0.197 millimeters b 3.80 4.00 0.150 0.157 c 1.35 1.75 0.053 0.069 d 0.33 0.51 0.013 0.020 g 1.27 bsc 0.050 bsc h 0.10 0.25 0.004 0.010 j 0.19 0.25 0.007 0.010 k 0.40 1.27 0.016 0.050 m 0 8 0 8 n 0.25 0.50 0.010 0.020 s 5.80 6.20 0.228 0.244 ?x? ?y? g m y m 0.25 (0.010) ?z? y m 0.25 (0.010) z s x s m
MC34268 http://onsemi.com 5 package dimensions dpak?3 dt suffix case 369a?13 issue ab d a k b r v s f l g 2 pl m 0.13 (0.005) t e c u j h ?t? seating plane z dim min max min max millimeters inches a 0.235 0.250 5.97 6.35 b 0.250 0.265 6.35 6.73 c 0.086 0.094 2.19 2.38 d 0.027 0.035 0.69 0.88 e 0.033 0.040 0.84 1.01 f 0.037 0.047 0.94 1.19 g 0.180 bsc 4.58 bsc h 0.034 0.040 0.87 1.01 j 0.018 0.023 0.46 0.58 k 0.102 0.114 2.60 2.89 l 0.090 bsc 2.29 bsc r 0.175 0.215 4.45 5.46 s 0.020 0.050 0.51 1.27 u 0.020 --- 0.51 --- v 0.030 0.050 0.77 1.27 z 0.138 --- 3.51 --- notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 123 4 5.80 0.228 2.58 0.101 1.6 0.063 6.20 0.244 3.0 0.118 6.172 0.243 mm inches scale 3:1 *for additional information on our pb?free strategy and soldering details, please download the on semiconductor soldering and mounting techniques reference manual, solderrm/d. soldering footprint* dpak?3
MC34268 http://onsemi.com 6 package dimensions sot?223 st suffix case 318e?04 issue k h s f a b d g l 4 123 0.08 (0003) c m k j dim a min max min max millimeters 0.249 0.263 6.30 6.70 inches b 0.130 0.145 3.30 3.70 c 0.060 0.068 1.50 1.75 d 0.024 0.035 0.60 0.89 f 0.115 0.126 2.90 3.20 g 0.087 0.094 2.20 2.40 h 0.0008 0.0040 0.020 0.100 j 0.009 0.014 0.24 0.35 k 0.060 0.078 1.50 2.00 l 0.033 0.041 0.85 1.05 m 0 10 0 10 s 0.264 0.287 6.70 7.30 notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: inch. 1.5 0.059 mm inches scale 6:1 3.8 0.15 2.0 0.079 6.3 0.248 2.3 0.091 2.3 0.091 2.0 0.079 *for additional information on our pb?free strategy and soldering details, please download the on semiconductor soldering and mounting techniques reference manual, solderrm/d. soldering footprint* sot?23 on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for an y particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, in cluding without limitation special, consequential or incidental damages. atypicalo parameters which may be provided in scillc data sheets and/or specifications can and do vary in different a pplications and actual performance may vary over time. all operating parameters, including atypicalso must be validated for each customer application by customer's technical e xperts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc prod uct could create a situation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indem nify and hold scillc and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney f ees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that scillc was neglig ent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. this literature is subject to all applicable copyright laws and is not for resale in any manner. publication ordering information n. american technical support : 800?282?9855 toll free usa/canada japan : on semiconductor, japan customer focus center 2?9?1 kamimeguro, meguro?ku, tokyo, japan 153?0051 phone : 81?3?5773?3850 MC34268/d literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 303?675?2175 or 800?344?3860 toll free usa/canada fax : 303?675?2176 or 800?344?3867 toll free usa/canada email : orderlit@onsemi.com on semiconductor website : http://onsemi.com order literature : http://www.onsemi.com/litorder for additional information, please contact your local sales representative.
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