lt1076-5 1 10765fc typical application features applications description 5v step-down switching regulator the lt ? 1076-5 is a 2a ? xed 5v output monolithic bipolar switching regulator which requires only a few external parts for normal operation. the power switch, all oscillator and control circuitry, all current limit components, and an output monitor are included on the chip. the topology is a classic positive buck con? guration but several design innova- tions allow this device to be used as a positive-to-negative converter, a negative boost converter, and as a ? yback con- verter. the switch output is speci? ed to swing 40v below ground, allowing the lt1076-5 to drive a tapped inductor in the buck mode with output currents up to 4a. the lt1076-5 uses a true analog multiplier in the feedback loop. this makes the device respond nearly instantaneously to input voltage ? uctuations and makes loop gain indepen- dent of input voltage. as a result, dynamic behavior of the regulator is signi? cantly improved over previous designs. on-chip pulse by pulse current limiting makes the lt1076- 5 nearly bust-proof for output overloads or shorts. the input voltage range as a buck converter is 8v to 60v, but a self-boot feature allows input voltages as low as 5v in the inverting and boost con? gurations. the lt1076-5 is available in a low cost 5- and 7-lead to- 220 packages with frequency pre-set at 100khz and current limit at 2.6a. see application note 44 for design details. basic positive buck converter n fixed 5v output n 2a on-board switch n 100khz switching frequency n 2% output voltage tolerance over temperature n greatly improved dynamic behavior n available in low cost 5- and 7-lead packages n only 9.5ma quiescent current n operates up to 60v input n 5v output buck converter n tapped inductor buck converter with 4a output at 5v n positive-to-negative converter , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. lt1076-5 v sw sense v c gnd r31.5k c20.033 f c3200 f 100 h** ? mbr340* mbr330p may be usedfor v in 25v coiltronics #100-1-52hurricane #hl-ag210ll value may be reduced to 50 h for output loads below 1.5a 8v to 40v c1500 f 25v lt1076-5 ta01 v in 5v 1.8a * ** ? + + downloaded from: http:///
lt1076-5 2 10765fc absolute maximum ratings input voltage lt1076-5 .............................................................45v lt1076hv-5 .........................................................64v switch voltage with respect to input voltage lt1076-5 ..............................................................64v lt1076hv-5 .........................................................75v switch voltage with respect to ground pin (v sw negative ) lt1076-5 (note 6) ................................................35v lt1076hv-5 (note 6) ...........................................45v (note 1) symbol conditions min typ max units switch on voltage (note 2) i sw = 0.5a i sw = 2a ll 1.21.7 vv switch off leakage v in = 25v, vsw = 0 v in = 25v, vsw = 0 150250 aa q package 5-lead plastic dd front view v in v sw gndv c fb/sense 54 3 2 1 jc = 4c/w, ja = 30c/w r package 7-lead plastic dd front view tab is gnd shdnv c sensegnd i lim v sw v in 76 5 4 3 2 1 jc = 4c/w, ja = 30c/w order part number order part number lt1076cq-5 lt1076cr-5 t package 5-lead plastic to-220 front view tab is gnd 54 3 2 1 v in gndsense v sw v c leads are formed standard for straight leads, order flow 06 jc = 4c/w, ja = 50c/w t7 package 7-lead plastic to-220 shdnsense i lim v in v c gndv sw front view tab is gnd 76 5 4 3 2 1 jc = 4c/w, ja = 50c/w order part number order part number lt1076ct-5 lt1076hvct-5 lt1076it-5 lt1076hvit-5 lt1076ct7-5 order options tape and reel: add #tr lead free: add #pbf lead free tape and reel: add #trpbf lead free part marking: http://www.linear.com/leadfree/ consult ltc marketing for parts speci? ed with wider operating temperature ranges. *the temperature grade is identi? ed by a label on the shipping container. package/order information sense pin voltage ............................................ C2v, 10v maximum operating ambient temperature range lt1076c-5, lt1076hvc-5 ....................... 0c to 70c lt1076i-5, lt1076hvi-5 ..................... C40c to 85c maximum operating junction temperature range lt1076c-5, lt1076hvc-5 ..................... 0c to 125c lt1076i-5, lt1076hvi-5 ................... C40c to 125c maximum storage temperature ............ C65c to 150c lead temperature (soldering, 10 sec) .................. 300c electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t j = 25c. v in = 25v, unless otherwise noted. downloaded from: http:///
lt1076-5 3 10765fc electrical characteristics note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: to calculate maximum switch on voltage at currents between low and high conditions, a linear interpolation may be used.note 3: a sense pin voltage (v sense ) of 5.5v forces the vc pin to its low clamp level and the switch duty cycle to zero. this approximates the zero load condition where duty cycle approaches zero. note 4: total voltage from v in pin to ground pin must be 8v after start- up for proper regulation. for t a < 25c, limit = 5v. note 5: switch frequency is internally scaled down when the sense pin voltage is less than 2.6v to avoid extremely short switch on times. during the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t j = 25c. v in = 25v, unless otherwise noted. current limit testing, v sense is adjusted to give a minimum switch on time of 1ms.note 6: switch to input voltage limitation must also be observed. note 7: v max = 40v for the lt1076-5 and 60v for the lt1076hv-5. note 8: error ampli? er voltage gain and transconductance are speci? ed relative to the internal feedback node. to calculate gain and transconductance from the sense pin (output) to the v c pin, multiply by 0.44.note 9: does not include switch leakage. note 10: i rk k lim lim 1 5 symbol conditions min typ max units supply current (note 3) v out = 5.5v, v in 40v 40v < v in < 60v v shdn = 0.1v (device shutdown) (note 9) ll 8.59.0 140 1112 300 mama a minimum supply voltage normal mode start-up mode (note 4) ll 7.33.5 8.04.8 vv switch current limit (note 5) i lim = open r lim = 10k (note 10) r lim = 7k (note 10) l 2 2.6 1.81.2 3.2 a aa maximum duty cycle l 85 90 % switching frequency t j 125c v out = v sense = 0v (note 5) l 9085 100 20 110120 khzkhz khz switching frequency line regulation 8v v in v max (note 8) l 0.03 0.1 %/v error ampli? er voltage gain (note 8) 1v v c 4v 2000 v/v error ampli? er transconductance (note 8) 3700 5000 8000 mho error ampli? er source and sink current source (v sense = 4.5v) sink (v sense = 5.5v) 100 0.7 140 1.0 225 1.6 a ma sense pin divider resistance 358 k sense voltage v c = 2v l 4.85 5 5.15 v output voltage tolerance v out (nominal) = 5v all conditions of input voltage, output voltage, temperature and load current l 0.51.0 23 %% output voltage line regulation 8v v in v max (note 7) l 0.005 0.02 %/v vc voltage at 0% duty cycle over temperature l 1.5 C4.0 v mv/c multiplier reference voltage 24 v shutdown pin current v shdn = 5v v shdn v threshold ( ? 2.5v) 51 02 0 50 aa shutdown thresholds switch duty cycle = 0 fully shut down 2.20.1 2.450.30 2.70.5 vv thermal resistance junction to case 4 c / w downloaded from: http:///
lt1076-5 4 10765fc package description q(dd5) 0502 .028 ?.038 (0.711 ?0.965) typ .143 +.012?020 () 3.632 +0.305 0.508 .067 (1.702) bsc .013 ?.023 (0.330 ?0.584) .095 ?.115 (2.413 ?2.921) .004 +.008?004 () 0.102 +0.203 0.102 .050 .012 (1.270 0.305) .059 (1.499) typ .045 ?.055 (1.143 ?1.397) .165 ?.180 (4.191 ?4.572) .330 ?.370 (8.382 ?9.398) .060 (1.524) typ .390 ?.415 (9.906 ?10.541) 15 typ .420 .350 .565 .090 .042 .067 recommended solder pad layout .325 .205 .080 .565 .090 recommended solder pad layout for thicker solder paste applications .042 .067 .420 .276 .320 note:1. dimensions in inch/(millimeter) 2. drawing not to scale .300 (7.620) .075 (1.905) .183 (4.648) .060 (1.524) .060 (1.524) .256 (6.502) bottom view of dd pak hatched area is solder plated copper heat sink q package 5-lead plastic dd pak (reference ltc dwg # 05-08-1461) downloaded from: http:///
lt1076-5 5 10765fc r (dd7) 0502 .026 ?.035 (0.660 ?0.889) typ .143 +.012?020 () 3.632 +0.305 0.508 .050 (1.27) bsc .013 ?.023 (0.330 ?0.584) .095 ?.115 (2.413 ?2.921) .004 +.008?004 () 0.102 +0.203 0.102 .050 .012 (1.270 0.305) .059 (1.499) typ .045 ?.055 (1.143 ?1.397) .165 ?.180 (4.191 ?4.572) .330 ?.370 (8.382 ?9.398) .060 (1.524) typ .390 ?.415 (9.906 ?10.541) 15 typ .420 .350 .565 .090 .035 .050 .325 .205 .080 .565 recommended solder pad layout for thicker solder paste applications recommended solder pad layout .090 .035 .050 .420 .276 .320 note:1. dimensions in inch/(millimeter) 2. drawing not to scale .300 (7.620) .075 (1.905) .183 (4.648) .060 (1.524) .060 (1.524) .256 (6.502) bottom view of dd pak hatched area is solder plated copper heat sink r package 7-lead plastic dd pak (reference ltc dwg # 05-08-1462) downloaded from: http:///
lt1076-5 6 10765fc package description t5 (to-220) 0801 .028 ?.038 (0.711 ?0.965) .067 (1.70) .135 ?.165 (3.429 ?4.191) .700 ?.728 (17.78 ?18.491) .045 ?.055 (1.143 ?1.397) .095 ?.115 (2.413 ?2.921) .013 ?.023 (0.330 ?0.584) .620 (15.75) typ .155 ?.195* (3.937 ?4.953) .152 ?.202 (3.861 ?5.131) .260 ?.320 (6.60 ?8.13) .165 ?.180 (4.191 ?4.572) .147 ?.155 (3.734 ?3.937) dia .390 ?.415 (9.906 ?10.541) .330 ?.370 (8.382 ?9.398) .460 ?.500 (11.684 ?12.700) .570 ?.620 (14.478 ?15.748) .230 ?.270 (5.842 ?6.858) bsc seating plane * measured at the seating plane t package 5-lead plastic to-220 (standard) (reference ltc dwg # 05-08-1421) downloaded from: http:///
lt1076-5 7 10765fc information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description .050 (1.27) .026 ?.036 (0.660 ?0.914) t7 (to-220) 0801 .135 ?.165 (3.429 ?4.191) .700 ?.728 (17.780 ?18.491) .045 ?.055 (1.143 ?1.397) .165 ?.180 (4.191 ?4.572) .095 ?.115 (2.413 ?2.921) .013 ?.023 (0.330 ?0.584) .620 (15.75) typ .155 ?.195* (3.937 ?4.953) .152 ?.202 (3.860 ?5.130) .260 ?.320 (6.604 ?8.128) .147 ?.155 (3.734 ?3.937) dia .390 ?.415 (9.906 ?10.541) .330 ?.370 (8.382 ?9.398) .460 ?.500 (11.684 ?12.700) .570 ?.620 (14.478 ?15.748) .230 ?.270 (5.842 ?6.858) bsc seating plane *measured at the seating plane t7 package 7-lead plastic to-220 (standard) (reference ltc dwg # 05-08-1422) downloaded from: http:///
lt1076-5 8 10765fc linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 1994 lt 0407 rev c printed in usa related parts part number description comments lt1074/hv 4.4a (i out ), 100khz high ef? ciency step-down dc/dc converter v in : 7.3v to 45v/64v, v out(min) : 2.21v, i q : 8.5ma, i shdn : 10a, dd5/7, to-2205/7 lt3430 60v, 2.75a (i out ), 200khz high ef? ciency step-down dc/dc converter v in : 5.5v to 60v, v out(min) : 1.20v, i q : 2.5ma, i shdn : 25a, tssop16e lt1956 60v, 1.2a (i out ), 500khz high ef? ciency step-down dc/dc converter v in : 5.5v to 60v, v out(min) : 1.20v, i q : 2.5ma, i shdn : 25a, tssop16e downloaded from: http:///
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