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lt3091 1 3091fa for more information www.linear.com/lt3091 output noise: 10hz to 100khz typical application features description ?36v, 1.5a negative linear regulator with programmable current limit the lt ? 3091 is a 1. 5a , low dropout negative linear regulator that is easily paralleled to increase output current or spread heat on surface mounted boards . designed with a precision current reference followed by a high performance rail-to-rail voltage buffer , this regulator finds use in applications requiring precision output , high current with no heat sink , output adjustability to zero and low dropout voltage . the device can also be configured as a 3-terminal floating regulator. the lt3091 features fast transient response , high psrr and output noise as low as 18 v rms . the lt3091 generates a wide output voltage range (0v to C32v) while maintain - ing unity gain operation . this yields virtually constant bandwidth, load regulation , psrr and noise , independent of the programmed output voltage. the lt3091 supplies 1.5a at a typical dropout voltage of 300mv. operating quiescent current is nominally 1.2ma and drops to << 1a in shutdown . a single resistor ad - justs the lt3091 s precision programmable current limit . the device s positive or negative current monitor either sources a current (0. 25ma /a) or sinks a current (0. 5ma /a) proportional to output current . built-in protection includes reverse output protection , internal current limit with fold - back and thermal shutdown with hysteresis. applications l , lt , lt c , lt m , linear technology and the linear logo are registered trademarks and thinsot is a trademark of linear technology corporation. all other trademarks are the property of their respective owners. patent pending. n output current: 1.5a n single resistor sets output voltage n 50a set pin current: 1% initial accuracy n programmable current limit n positive or negative output current monitor n parallelable for higher current and heat spreading n low dropout voltage: 300mv n low output noise: 18v rms (10hz to 100khz) n conigurable as a 3-terminal floating regulator n wide input voltage range: C1.5v to C36v n rail-to-rail output voltage range: 0v to C32v n positive/negative shutdown logic or uvlo n programmable cable drop compensation n load regulation: 1.2mv (1ma to 1.5a) n stable with 10f minimum output capacitor n stable with ceramic or tantalum capacitors n thermally enhanced 14-lead 4mm 3mm dfn, 16-lead tssop, 7-lead to-220 and dd packages n post regulator for switching supplies n low noise instrumentation and rf supplies n rugged industrial supplies n precision power supplies v in : C3.5v c out : 10f, c set : 0.1f v out : C2.5v i l : 1.5a 1ms/div v out 100v/div 3091 g39 lt3091 v out C2.5vmax i out 1.5a set gnd ilim shdn 3091 ta01a ? + 50a imonp out imonn 0.1f 10f 49.9k 6.65k to adc (imon) in v in C3v to C10v 5k 3.3v 10f 0.1f downloaded from: http:///
lt3091 2 3091fa for more information www.linear.com/lt3091 pin configuration absolute maximum ratings in pin voltage ( note 3 ) with respect to gnd pin ........................... 0. 3v , C 40v ilim pin voltage with respect to in pin ( note 3 ) ................ C0. 3v , 0. 7v imonp pin voltage with respect to in pin ( note 3 ) ................. C0. 3v , 40v with respect to gnd pin ............................ C 40v , 20v with respect to imonn pin ........................ C 40v , 20v imonn pin voltage with respect to in pin ( note 3 ) ................. C0. 3v , 40v with respect to gnd pin ............................ C 40v , 20v shdn pin voltage with respect to in pin ( note 3 ) ................. C0. 3v , 55v with respect to gnd pin ............................ C 40v , 20v (note 1) 12 3 4 5 6 7 1413 12 11 10 98 outout out out gnd set shdn inin in in ilim imonp imonn top view 15 in de package 14-lead (4mm 3mm) plastic dfn t jmax = 150c, ja = 27c/w, jc = 5.5c/w exposed pad (pin 15) is in, must be soldered to pcb fe package 16-lead plastic tssop 12 3 4 5 6 7 8 top view 1615 14 13 12 11 10 9 inin in in ilim imonp imonn nc outout out out gnd set shdn nc 17 in t jmax = 150c, ja = 25c/w, jc = 8c/w exposed pad (pin 17) is in, must be soldered to pcb r package 7-lead plastic dd front view tab is in outgnd set in shdn imonn ilim 76 5 4 3 2 1 t jmax = 150c, ja = 15c/w, jc = 3c/w t7 package 7-lead plastic to-220 outgnd set in shdn imonn ilim front view tab is in 76 5 4 3 2 1 t jmax = 150c, ja = 34c/w, jc = 3c/w set pin voltage with respect to in pin ( note 3 ) ................. C0. 3v , 36v with respect to gnd pin .................................... 36v set pin current ( note 9 )........................................ 5ma out pin voltage with respect to in pin ( note 3 ) ................. C0. 3v , 36v with respect to gnd pin .................................... 36v output short-circuit duration .......................... indefinite operating junction temperature range ( note 2 ) e- , i-grade ........................................ C 40 c to 125c mp-grade ......................................... C 55 c to 150c h-grade ............................................ C 40 c to 150c storage temperature range .................. C 65 c to 150c lead temperature ( soldering , 10 sec ) fe , r, t7 packages .......................................... 300 c downloaded from: http:///
lt3091 3 3091fa for more information www.linear.com/lt3091 lead free finish tape and reel part marking* package description temperature range lt3091ede#pbf lt3091ede#trpbf 3091 14-lead (4mm 3mm) plastic dfn C40c to 125c lt3091ide#pbf lt3091ide#trpbf 3091 14-lead (4mm 3mm) plastic dfn C40c to 125c lt3091hde#pbf lt3091hde#trpbf 3091 14-lead (4mm 3mm) plastic dfn C40c to 150c lt3091mpde#pbf lt3091mpde#trpbf 3091 14-lead (4mm 3mm) plastic dfn C55c to 150c lt3091efe#pbf lt3091efe#trpbf 3091fe 16-lead plastic tssop C40c to 125c lt3091ife#pbf lt3091ife#trpbf 3091fe 16-lead plastic tssop C40c to 125c lt3091hfe#pbf lt3091hfe#trpbf 3091fe 16-lead plastic tssop C40c to 150c lt3091mpfe#pbf lt3091mpfe#trpbf 3091fe 16-lead plastic tssop C55c to 150c lt3091er#pbf lt3091er#trpbf lt3091r 7-lead plastic dd-pak C40c to 125c lt3091ir#pbf lt3091ir#trpbf lt3091r 7-lead plastic dd-pak C40c to 125c lt3091hr#pbf lt3091hr#trpbf lt3091r 7-lead plastic dd-pak C40c to 150c lt3091mpr#pbf lt3091mpr#trpbf lt3091r 7-lead plastic dd-pak C55c to 150c lt3091et7#pbf n/a lt3091t7 7-lead plastic to-220 C40c to 125c lt3091it7#pbf n/a lt3091t7 7-lead plastic to-220 C40c to 125c lt3091ht7#pbf n/a lt3091t7 7-lead plastic to-220 C40c to 150c lt3091mpt7#pbf n/a lt3091t7 7-lead plastic to-220 C55c to 150c consult ltc marketing for parts specified with wider operating temperature ranges . * the temperature grade is identified by a label on the shipping container . for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ . some packages are available in 500 unit reels through designated sales channels with #trmpbf suffix. electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. parameter conditions min typ max units minimum in voltage (note 11) i load = 500ma i load = 1.5a l C1.9 C1.5 C1.5 v v set pin current (i set ) v in = C1.9v, i load = 1ma C36v < v in < C1.9v, 1ma < i load < 1.5a (note 5) l 49.5 49 50 50 50.5 51 a a output offset voltage, v os (v out C v set ) v in = C1.9v, i load = 1ma C36v < v in < C1.9v, 1ma < i load < 1.5a (note 5) (dfn, tssop) C36v < v in < C1.9v, 1ma < i load < 1.5a (note 5) (dd-pak, to-220) l l C1.2 C2 C3.5 1.2 2 3.5 mv mv mv line regulation: ? i set / ? v in line regulation: ? v os / ? v in v in = C1.9v to C36v, i load = 1ma v in = C1.9v to C36v, i load = 1ma 1.5 2.5 na/v v/v load regulation: ? i set load regulation: ? v os i load = 1ma to 1.5a i load = 1ma to 1.5a, v in = C1.9v (note 6) l 2.0 1.2 5.0 na mv output regulation with set pin voltage change: ? i set / ? v set ? v os / ? v set v set = 0v to C32v, v in = C36v, i load = 1ma v set = 0v to C32v, v in = C36v, i load = 1ma l l 0.2 2.5 2 40 na/v v/v order information ( http:// www .linear.com/product/lt3091#orderinfo ) downloaded from: http:///
lt3091 4 3091fa for more information www.linear.com/lt3091 electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. parameter conditions min typ max units dropout voltage v in = v out(nominal) (note 7) dfn and tssop to-220 and dd-pak i load = 1ma i load = 1ma i load = 100ma i load = 100ma i load = 500ma i load = 500ma i load = 1.5a i load = 1.5a i load = 1.5a i load = 1.5a l l l l l 173 176 185 300 360 225 270 225 280 230 320 360 450 420 525 mv mv mv mv mv mv mv mv mv mv gnd pin current v in = v out(nominal) (note 8) i load = 20a i load = 1ma i load = 100ma i load = 500ma i load = 1.5a l l l l l 1.2 1.2 2.6 9.3 40 2.0 2.0 5.5 20 80 ma ma ma ma ma error amplifier rms output noise (note 12) i load = 1.5a, bw = 10hz to 100khz, c out = 10f, c set = 0.1f 18 v rms reference current rms output noise (note 12) bw = 10hz to 100khz 10 na rms ripple rejection v in C v out = C1.5v (avg) v ripple = 500mv p-p , f ripple = 120hz , i load = 100ma , c out = 10 f, c set = 0 . 47 f v ripple = 50mv p-p , f ripple = 10khz, i load = 1.5a, c out = 10f, c set = 0.47f v ripple = 50mv p-p , f ripple = 1mhz, i load = 1.5a, c out = 10f, c set = 0.47f 70 85 45 20 db db db shdn pin turn-on threshold positive shdn rising negative shdn rising (in magnitude) l l 1.14 C1.36 1.23 C1.27 1.32 C1.18 v v shdn pin hysteresis positive shdn hysteresis negative shdn hysteresis 180 190 mv mv shdn pin current (note 10) v shdn = 0v v shdn = 15v v shdn = C15v C7 21 C4.5 1 30 a a a quiescent current in shutdown v in = C6v, v shdn = 0v v in = C6v, v shdn = 0v l 0.1 1 20 a a internal current limit (note 13) v in = C1.9v, v out = 0v v in = C13v, v out = 0v v in = C36v, v out = 0v v in = C1.9v, ? v out < 10mv l l l 1600 20 1550 1900 840 65 1850 2200 120 2150 ma ma ma ma programmable current limit programmable scale factor: C36v < v in < C1.9v, i out > 100ma (note 14) max i out : v in = C1.9v, r ilim = 13.3k max i out : v in = C1.9v, r ilim = 40k l l 1.35 450 20 1.5 500 1.65 550 a ? k a ma positive current monitor (note 15) positive current monitoring (imonp) scale factor i out = 500ma, v in = C2.5v, v imonn = 2v, v imonp = 0v i out = 1.5a, v in = C2.5v, v imonn = 2v, v imonp = 0v l l 113 338 0.25 125 375 137 412 ma/a a a negative current monitor negative current monitoring (imonn) scale factor i out = 500ma, v in = C2.5v, v imonn = 0v, v imonp = C2.5v i out = 1.5a, v in = C2.5v, v imonn = 0v, v imonp = C2.5v l l 225 675 0.5 250 750 275 825 ma/a a a minimum required load current (note 4) C36v < v in < C1.9v l 20 a thermal regulation iset 10ms pulse 0.04 %/w downloaded from: http:///
lt3091 5 3091fa for more information www.linear.com/lt3091 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. the lt3091 is tested and specified under pulsed load conditions such that t j ? t a . the lt3091e is guaranteed to meet performance specifications from 0c to 125c junction temperature. specifications over the C40c to 125c operating temperature range are assured by design, characterization, and correlation with statistical process controls. the lt3091i is guaranteed over the full C40c to 125c operating junction temperature range. the lt3091mp is 100% tested and guaranteed over the full C55c to 150c operating junction temperature range. the lt3091h is 100% tested at the 150c operating junction temperature. high junction temperatures degrade operating lifetimes. operating lifetime is derated at junction temperatures greater than 125c. note 3. parasitic diodes exist internally between the out, set, ilim, shdn , imonp, imonn, and gnd pins and the in pin. do not drive out, set, ilim, shdn , imonp, imonn, and gnd pins more than 0.3v below the in pin during fault conditions. these pins must remain at a voltage more positive than in during normal operation. note 4. the lt3091 may go out of regulation if the minimum output current requirement is not satisfied. note 5. maximum junction temperature limits operating conditions . the regulated output voltage specification does not apply for all possibl e combinations of input voltage and output current, primarily due to the internal current limit foldback which decreases current limit at v out C v in 7v . if operating at maximum output current, limit the input voltage range . if operating at maximum input voltage, limit the output current range . note 6. load regulation is kelvin sensed at the package. note 7. dropout voltage is the minimum output-to-input voltage differential needed to maintain regulation at a specified output current. in dropout, the output voltage is: v in + v dropout . note 8. gnd pin current is tested with v in = v out(nominal) and a current source load. therefore, the device is tested while operating in dropout. this is the worst-case gnd pin current. gnd pin current decreases at higher input voltages. note 9. the set pin is clamped to out with diodes through 12k resistors. these resistors and diodes only carry current under transient overloads or fault conditions. note 10. positive shdn pin current flows into the shdn pin. note 11. the shdn threshold must be met to ensure device operation. note 12. output noise decreases by adding a capacitor across the voltage setting resistor. adding this capacitor bypasses the voltage setting resistors thermal noise as well as the reference currents noise. output noise then equals the error amplifier noise (see applications information section). note 13. the internal back-up current limit circuitry incorporates foldback protection that decreases current limit for v out C v in 7v. some level of output current is provided at all v out C v in differential voltages. please consult the typical performance characteristic graph for current limit vs v out C v in . note 14. the current limit programming scale factor is specified while the internal backup current limit is not active. please note that the internal current limit has foldback protection for v out -to-v in differentials greater than 7v.note 15. for positive current monitoring, bias imonn to 2v above imonp. electrical characteristics typical performance characteristics t j = 25c, unless otherwise noted. set pin current set pin current offset voltage (v out C v set ) temperature (c) C75 set pin current (a) 50.550.4 50.2 50.0 50.350.1 49.9 49.8 49.7 49.6 49.5 25 C25 75 100 125 3091 g01 150 0 C50 50 i l = 1ma v out = C1.25v v in = C1.9v temperature (c) C75 offset voltage (mv) 2.01.5 0.5 0 1.0 C0.5C1.0 C1.5 C2.0 25 C25 75 100 125 3091 g03 150 0 C50 50 i l = 1ma v out = C1.25v v in = C1.9v 49 49.5 50.5 3091 g02 51 50 distribution (a) n = 4726 downloaded from: http:///
lt3091 6 3091fa for more information www.linear.com/lt3091 typical performance characteristics offset voltage set pin current offset voltage (v out C v set ) set pin current offset voltage (v out C v set ) load regulation t j = 25c, unless otherwise noted. input voltage (v) 0 set pin current (a) 50.550.4 50.2 50.0 50.350.1 49.9 49.8 49.7 49.6 49.5 C20 C10 C30 C35 3091 g05 C40 C15 C5 C25 i l = 1ma v out = C1.25v C55c25c 125c 150c input voltage (v) 0 offset voltage (mv) 2.01.5 0 1.00.5 C0.5C1.0 C1.5 C2.0 C20 C10 C30 C35 3091 g06 C40 C15 C5 C25 i l = 1ma v out = C1.25v C55c25c 125c 150c output voltage (v) 0 set pin current (a) 50.550.4 50.2 50.0 50.350.1 49.9 49.8 49.7 49.6 49.5 8 24 28 3091 g07 32 16 12 4 20 i l = 1ma v in = C36v C55c25c 125c 150c output voltage (v) 0 offset voltage (mv) 2.01.5 0 1.00.5 C0.5C1.0 C1.5 C2.0 C8 C24 C28 3091 g08 C32 C16 C12 C4 C20 i l = 1ma v in = C36v C55c25c 125c 150c temperature (c) C75 set pin current load regulation (na) offset voltage load regulation (mv) 3020 10 0 C10C20 2.52.0 1.5 1.0 0.5 0 C25 75 125 100 3091 g09 150 25 0 C50 50 ?i l = 1ma to 1.5a v in = C1.9v v out = C1.25v C2 C1 1 3091 g04 2 0 v os distribution (mv) n = 4726 quiescent current typical dropout voltage temperature (c) C75 quiescent current (ma) 1.41.2 0.8 0.6 1.00.4 0.2 0 25 C25 75 100 125 3091 g10 150 0 C50 50 r l = 61.9k (20a) v out = C1.25v v in = C1.9v v shdn = v in v shdn = 0v output current (a) 0 dropout voltage (mv) 450350 300 400200 150 100 50 250 0 1 1.25 3091 g11 1.5 0.50 0.25 0.75 C55c25c 125c 150c downloaded from: http:///
lt3091 7 3091fa for more information www.linear.com/lt3091 typical performance characteristics dropout voltage gnd pin current gnd pin current entering dropout minimum input voltage shdn turn-on threshold shdn pin hysteresis guaranteed dropout voltage (to-220 and dd packages) output current (a) 0 gnd pin current (ma) 4535 4020 15 10 5 25 0 0.8 1.2 0.6 1.0 1.4 3091 g15 1.6 0.2 0.4 v in = C3.5v v out = C3v C55c25c 125c 150c input voltage (v) C2.5 C2.6 C2.7 C2.8 C2.9 C3 C3.1 C3.2 C3.3 C3.4 C3.5 gnd pin current (ma) 40 4530 25 20 15 10 5 35 0 3091 g16 v out(nominal) = C3v i l = 500ma i l = 100ma i l = 1ma i l = 1.5a i l = 1a temperature (c) C75 C50 C25 0 25 50 75 100 125 150 minimum input voltage (v) C1.8 C2.0C1.4 C1.2 C1.0 C0.8 C0.6 C0.4 C0.2 C1.6 0 3091 g17 r set = 25k i l = 1ma temperature (c) C75 C50 C25 0 25 50 75 100 125 150 shdn pin hysteresis (v) 0.300.15 0.200.10 0.05 0.25 0 3091 g19 v in = C1.9v positive shdn hysteresis negative shdn hysteresis t j = 25c, unless otherwise noted. temperature (c) C75 dropout voltage (mv) 450350 300 400200 150 100 50 250 0 25 50 75 100 125 3091 g14 150 C25 C50 0 i l = 1.5a i l = 500ma i l = 1a i l = 1ma i l = 100ma temperature (c) C75 positive shdn turn-on thershold (v) negative shdn turn-on threshold (v) 1.3001.275 1.250 1.225 1.200 1.175 1.150 C1.300C1.275 C1.250 C1.225 C1.200 C1.175 C1.150 C25 75 125 100 3091 g18 150 25 0 C50 50 v in = C1.9v guaranteed dropout voltage (dfn and msop packages) output current (ma) 0 dropout voltage (mv) 600500 300 400200 100 0 1000 1250 3091 g12 1500 500 250 750 t j 150c t j 25c output current (ma) 0 dropout voltage (mv) 600500 300 400200 100 0 1000 1250 3091 g13 1500 500 250 750 t j 150c t j 25c downloaded from: http:///
lt3091 8 3091fa for more information www.linear.com/lt3091 imonn pin current at 1.5a imonn pin current at 500ma imonp pin current imonp pin current at 1.5a imonp pin current at 500ma programmable current limit shdn pin current shdn pin current imonn pin current typical performance characteristics shdn pin voltage (v) C36 C28 C20 C12 C4 4 12 20 shdn pin current (a) 3530 15 2010 50 C5 C10 25 C15 3091 g20 v in = C36v C55c25c 125c 150c temperature (c) C75 C50 C25 0 25 50 75 100 125 150 imonn current (a) 800780 770 760 750 720 740710 730 790700 3091 g23 v out = C1.2v v imonn = C0.5v v imonp = v in i load = 1.5a v in = C3v temperature (c) C75 C50 C25 0 25 50 75 100 125 150 imonn current (a) 268262 259 253 250 235 247244 241 238 265232 3091 g24 v out = C1.2v v imonn = C0.5v v imonp = v in i load = 500ma v in = C3v t j = 25c, unless otherwise noted. temperature (c) C75 C50 C25 0 25 50 75 100 125 150 imonp current (a) 400385 370 360 365350 395380 390375 350 3091 g26 v in = C3v v out = C1.2v v imonn = 3v v imonp = 0.5 i load = 1.5a temperature (c) C75 C50 C25 0 25 50 75 100 125 150 imonp current (a) 133129 125 121 123119 131127 117 3091 g27 v in = C3v v out = C1.2v v imonn = 3v v imonp = 0.5 i load = 500ma temperature (c) C75 C50 C25 0 25 50 75 100 125 150 current limit (ma) 1.61.3 1.0 1.51.2 0.9 1.41.1 0.8 0.7 0.5 0.3 0.60.4 0.2 0.1 0 3091 g28 r ilim = 13.3k r ilim = 20k r ilim = 40k v in = C2v v out = 0v temperature (c) C75 C50 C25 0 25 50 75 100 125 150 shdn pin current (a) 3025 15 10 50 20 C10 C5 3091 g21 v shdn = 15v v shdn = C15v v in = C15v output current (a) 0 0.2 0.4 0.6 0.8 1.0 1.2 1.6 1.4 imonp current (a) 400350 250 200 100 150 50 300 0 3091 g25 v out = C1.2v v in = C3v v imonn = 3v v imonp = 0.5v output current (a) 0 0.2 0.4 0.6 1.0 1.4 0.8 1.2 1.6 imonn current (a) 800700 500 400 300 200 100 600 0 3091 g22 v in = C3v v out = C1.2v v imonn = C0.5v v imonp = v in downloaded from: http:///
lt3091 9 3091fa for more information www.linear.com/lt3091 t j = 25c, unless otherwise noted. typical performance characteristics internal current limit input ripple rejection input ripple rejection input ripple rejection ripple rejection (120hz) programmable brick-wall current limit internal current limit internal current limit rms output noise temperature (c) C75 C50 C25 0 25 50 75 100 125 150 current limit (ma) 100 9070 30 5010 8040 6020 0 3091 g31 v in = C36v v out = 0v input-to-output differential (v) 0 current limit (a) 2.01.2 0.8 0.6 1.6 1.81.4 1.0 0.4 0.2 0 C12 C24 C30 3091 g32 C36 C18 C6 C55c25c 125c 150c v out = 0v output current (a) 0 1.5 0.5 1.0 output voltage (v) 1.41.2 1.0 0.8 0.6 0.4 0.2 0 3091 g29 r ilim = 13.3k r ilim = 40k r ilim = 20k r set = 25k v in = C3v temperature (c) C75 C50 C25 0 25 50 75 100 125 150 current limit (a) 2.01.8 1.6 1.4 1.2 1.0 0.8 0.4 0.60.2 0 3091 g30 v in = C1.9v v out = 0v frequency (hz) ripple rejection (db) 3091 g33 8070 60 50 30 4020 10 0 10 100 1k 1m 10m 100k 10k v out = C2.5v i load = 1.5a c set = 0.1f input ripple = 50mv rms C3.5v in C4v in frequency (hz) ripple rejection (db) 3091 g34 9080 70 60 50 30 4020 10 0 10 100 1k 1m 10m 100k 10k v out = C2.5v v in = C3.5v c set = 0.1f input ripple = 50mv rms i l = 1.5a i l = 500ma i l = 100ma frequency (hz) ripple rejection (db) 3091 g35 100 9080 70 50 6040 30 20 10 0 10 100 1k 1m 10m 100k 10k v out = C2.5v i load = 1.5a c set = 0.1f input ripple = 50mv rms c out = 10f, c set = 0.1f c out = 10f, c set = 0.47f c out = 22f, c set = 0.1f temperature (c) C75 ripple rejection (db) 100 9085 9580 75 70 25 C25 75 100 125 3091 g36 150 0 C50 50 v in = C4v v out = C2.5v i load = 1.5a c set = 0.47f c out = 10f set pin capacitance (nf) 0.1 1 output noise (v rms ) 1000 10 100 100 10 3091 g7 1000 downloaded from: http:///
lt3091 10 3091fa for more information www.linear.com/lt3091 t j = 25c, unless otherwise noted. typical performance characteristics load transient response, C3v out output noise: 10hz to 100khz output noise: 10hz to 100khz fast input supply start-up line transient response slow input supply ramp-up and ramp-down fast input supply start-up fast shdn start-up fast shdn start-up v in : C5v to C4v c out : 10f, c set : 0.1f v out : C3v i l : 1.5a, shdn = in 5s/div ?v out 50mv/div v in 500mv/div 3091 g41 v in : C3.5v c out : 10f, c set : 20pf v out : C2v i l : 1.5a 1ms/div v out 1mv/div 3091 g38 v in : C3.5v c out : 10f, c set : 0.1f v out : C2.5v i l : 1.5a 1ms/div v out 100v/div 3091 g39 v in : 0v to C5v c out : 10f, c set : 0.1f v out : 0v to C3v i l : 1.5a, shdn = in 5ms/div 0v v out 1v/div v in 2v/div 0v 3091 g44 i load : 20ma to 1.5a c out : 10f, c set : 0.1f v out : C3v v in = C4v, shdn = in 20s/div i load 500ma/div ?v out 100mv/div 3091 g40 v in : C5v to 0v c out : 10f, c set : 0.1f v out : C3v to 0v i l : 1.5a, shdn = in 50ms/div v in 1v/div v out 1v/div 0v 3091 g42 v in : 0v to C5v c out : 10f, c set : 100pf v out : 0v to C3v i l : 1.5a, shdn = in 20s/div v out 1v/div v in 2v/div 0v0v 3091 g43 v in : C5v c out : 10f, c set : 100pf 20s/div 0v v out 1v/div v shdn 2v/div 0v 3091 g45 v in : C5v c out : 10f, c set : 0.1f 5ms/div 0v v out 1v/div v shdn 2v/div 0v 3091 g46 downloaded from: http:///
lt3091 11 3091fa for more information www.linear.com/lt3091 pin functions in ( pins 1 C4, exposed pad 15 / pins 1 C4, exposed pad ?17/ pin 4 , tab / pin 4 , tab ): input . these pins supply power to the regulator . the exposed backside pad of the dfn and tssop packages , as well as the tab of the dd-pak and to-220 packages , is an electrical connection to in and the device s substrate . for proper electrical and thermal performance, tie all in pins together and tie in to the exposed backside / tab of the package on the pcb . see the applications information section for thermal considerations and calculating junction temperature . the lt3091 requires a bypass capacitor at in . in general , a battery s output impedance rises with frequency , so include a bypass ca - pacitor in battery powered applications . an input bypass capacitor in the range of 4.7f to 10f generally suffices , but applications with large load transients or longer input lines may require higher input capacitance to prevent input supply droop or input ringing. ilim ( pin 5 / pin 5 / pin 1 / pin 1 ): current limit programming pin. connecting an external resistor between the ilim and in pins programs the current limit set point . for best accuracy, kelvin connect this resistor to the in pins . the programming scale factor is nominally 20a ? k . current limit is accurate to 10% over temperature . if unused , tie ilim to in and the internal current limit protects the part . a parasitic substrate diode exists between the lt3091s ilim and in pins . therefore , do not drive ilim more than 0.3v below in during normal operation or during a fault condition. imonp ( pin 6 / pin 6 /na/na): positive current monitoring pin. for positive current monitoring , connect a resistor between imonp and gnd . imonp sources current equal to 1/ 4000 of output current . for negative current monitoring , tie this pin to in . for proper operation , in and imonp must be at least 2v below imonn . if unused , tie imonp to in . a parasitic substrate diode exists between the lt3091s imonp and in pins . therefore , do not drive imonp more than 0.3v below in during normal operation or during a fault condition. imonn ( pin 7 / pin 7 / pin 2 / pin 2 ): negative current monitor - ing pin . for negative current monitoring , connect a resistor between imonn and gnd . imonn sinks current equal to 1/ 2000 of output current . for positive current monitor - ing, bias imonn to a positive supply voltage ( at least 2v above imonp ). if unused , tie imonn to the gnd pin . a parasitic substrate diode exists between the lt3091s imonn and in pins . therefore , do not drive imonn more than 0.3v below in during normal operation or during a fault condition.shdn ( pin 8 / pin 10 / pin 3 / pin 3 ): shutdown . use the shdn pin to put the lt3091 into a micropower shutdown state and to turn off the output voltage . the shdn function is bidirectional, allowing either positive or negative logic to turn the regulator on /off. the shdn pin threshold volt - ages are referenced to gnd . the output of the lt3091 is off if the shdn pin is pulled within 0.45v of gnd . driv - ing the shdn pin more than 1.4v turns the lt3091 on . drive the shdn pin with either a logic gate or with open collector/ drain logic using a pull-up resistor . the resistor supplies the pull-up current of the open collector /drain gate. the maximum shdn pin current is 7a out of the pin ( for negative logic ) or 30a into the pin ( for positive logic). if the shdn function is unused , connect the shdn pin to v in or a positive bias voltage to turn the device on . do not float the shdn pin . as detailed in the applications information section , the shdn pin can also be used to set a programmable undervoltage lockout ( uvlo ) threshold . a parasitic diode exists between the lt3091s shdn and in pins. therefore , do not drive shdn more than 0.3v below in during normal operation or during a fault condition . set ( pin 9 / pin 11 / pin 5 / pin 5 ): set . this pin is the invert - ing input to the error amplifier and the regulation setpoint for the device . a precision fixed current of 50a flows into this pin . connecting a resistor from set to gnd programs the lt3091 s output voltage . output voltage range is from (dfn/ tssop/r/ t7) downloaded from: http:///
lt3091 12 3091fa for more information www.linear.com/lt3091 pin functions (dfn/ tssop/r/ t7) zero to C32v. adding a bypass capacitor from set to gnd improves transient response , psrr , noise performance and soft starts the output . kelvin connect the gnd side of the set pin resistor to the load for optimum load regulation performance. a parasitic substrate diode exists between the lt3091 s set and in pins . therefore , do not drive set more than 0.3v below in during normal operation or during a fault condition.gnd ( pin 10 / pin 12 / pin 6 / pin 6 ): ground . this pin supplies the lt3091' s quiescent current and the drive current to the npn pass transistor . the lt3091' s gnd pin is highly versatile. depending on application s requirements , it can be tied to the system ground , a positive voltage , or the out pin . a parasitic substrate diode exists between the lt3091 s gnd and in pins . therefore , do not drive gnd more than 0.3v below in during normal operation or during a fault condition. out ( pins 11 C14/ pins 13 C16/ pin 7 / pin 7 ): output . these pins supply power to the load . tie all out pins together for best performance . use a minimum output capacitor of 10f with an esr less than 500m to prevent oscillations . as mentioned in the electrical characteristics table , a minimum load current of 20a is required to prevent instability . large load transient applications require larger output capacitors to limit peak voltage transients . see the applications information section for more information on output capacitance . a parasitic substrate diode exists between out and in pins of the lt3091. therefore , do not drive out more than 0.3v below in during normal operation or during a fault condition. nc (na/ pins 8 C9/na/na): no connection . no connect pins have no connection to internal circuitry and may be tied to v in , gnd or floated. downloaded from: http:///
lt3091 13 3091fa for more information www.linear.com/lt3091 block diagram ? + 50a rail-to-railerror amp 20.25a out shdn gnd imonn 0.0675 6.33k internalcurrent limit C1.27v 1.23v bidirectional shutdown 3091 bd r set r load c out driver ? + ? + ? + ? + ? + ? + 3k 135 ilim in imonp positive or negative current monitor programmable current limit 2x 1x 225mv +? v r ilim c in in set bias downloaded from: http:///
lt3091 14 3091fa for more information www.linear.com/lt3091 the lt3091 is a 1.5a, rail-to-rail output , negative low dropout linear regulator featuring very low output noise , high bandwidth , precision programmable current limit , precision positive or negative current monitor , and bi - directional shutdown . the lt3091 supplies 1.5a at a typical dropout voltage of 300mv. unlike other devices , the lt3091 does not require a separate supply to achieve low dropout performance . the 1.2ma quiescent current drops to well below 1a in shutdown. the lt3091 is easy to use and incorporates all of the pro - tection features expected in high performance regulators . included are short circuit protection , safe operating area protection, as well as thermal shutdown with hysteresis . in bipolar supply applications where the regulator s load is returned to a positive supply , out can be pulled above gnd up to 36v and still allow the lt3091 to safely startup . output voltage the lt3091 incorporates a zero tc 50a reference cur - rent source that flows into the set pin . the set pin is the inverting input of the error amp . connecting a resistor from set to ground generates a voltage that becomes the reference point for the error amplifier ( see figure 1 ). the reference voltage is a straight multiplication of the set pin current and the resistor value (ohm s law , v = i ? r ). the rail-to-rail error amp s unity gain configuration produces a low impedance voltage on its noninverting input , i .e. the out pin . output voltage is programmable from 0v ( using zero resistor ) to v in plus dropout . table 1 lists many common output voltages and its corresponding 1 % rset resistance. table 1. 1% resistor for common output voltages v out (v) r set (k) C2.5 49.9 C3 60.4 C3.3 66.5 C5 100 C12 243 C15 301 applications information the benefits of using a current reference , as opposed to a voltage reference as in conventional regulators such as the lt1185, lt1175, lt1964 and lt3015, is that the device always operates in a unity gain configuration , regardless of the programmed output voltage . this allows the lt3091 to have loop gain , frequency response , and bandwidth independent of the output voltage . moreover , none of the error amp gain is needed to amplify the set pin voltage to a higher output voltage ( in magnitude ). as a result , output load regulation is specified in terms of millivolts and not a fixed percentage of the output voltage. since the zero tc current source is very accurate , the set pin resistor is the limiting factor in achieving high accu - racy; hence , it must be a precision resistor . moreover , any leakage paths to and from the set pin create errors in the output voltage . if necessar y , use high quality insulation (e.g. teflon , kel-f ); moreover , cleaning of all insulating surfaces to remove fluxes and other residues may be required . high humidity environments may require a surface coating at the set pin to provide a moisture barrier. minimize board leakage by encircling the set pin with a guard ring operated at a potential close to itself C ideally the guard ring should be tied to the out pin . guarding both sides of the circuit board is required . bulk leakage figure 1. basic adjustable regulator lt3091 v out C2.5vmax i out 1.5a set gnd ilim shdn 3091 f01 ? + 50a imonn out 0.1f c in 10f r set 49.9k in v in C3v to C10v r ilim imonp c out 10f 5k downloaded from: http:///
lt3091 15 3091fa for more information www.linear.com/lt3091 applications information reduction depends on the guard ring width . leakages as small as 50na into or out of the set pin creates a 0 .1% error in the reference voltage . leakages of this magnitude , coupled with other sources of leakage , can cause significant errors in the output voltage , especially over wide operating temperature range . figure 2 illustrates a typical guard ring layout technique.if guard ring techniques are used , then set pin stray capacitance is practically eliminated . since the set pin is a high impedance node , unwanted signals may couple into the set pin and cause erratic behavior . this is most noticeable when operating with a minimum output capacitor at light load currents . the simplest remedy is to bypass the set pin with a small capacitance to ground C 100pf is generally sufficient. 30- awg wire with a diameter of 0 .01". one foot of 30-awg wire has 465nh of self inductance. several methods exist to reduce a wire s self inductance . one method divides the current flowing towards the lt3091 between two parallel conductors . in this case , placing the wires further apart reduces the inductance ; up to a 50 % reduction when placed only a few inches apart . splitting the wires connects two equal inductors in parallel . however, when placed in close proximity to each other , mutual inductance adds to the overall self inductance of the wires . the second and most effective technique to reduce overall inductance is to place the forward and return current conductors ( the input wire and the ground wire) in close proximity . two 30- awg wires separated by 0.02" reduce the overall self inductance to about one-fifth of a single wire. if a battery , mounted in close proximity , powers the lt3091, a 10f input capacitor suffices for stability . however, if a distantly located supply powers the lt3091, use a larger value input capacitor . use a rough guideline of 1f ( in addition to the 10f minimum ) per 8 " of wire length. the minimum input capacitance needed to stabi - lize the application also varies with power supply output impedance variations . placing additional capacitance on the lt3091 s output also helps . however , this requires an order of magnitude more capacitance in comparison with additional lt3091 input bypassing . series resistance between the supply and the lt3091 input also helps stabi - lize the application ; as little as 0.1 to 0.5 suffices . this impedance dampens the lc tank circuit at the expense of dropout voltage . a better alternative is to use higher esr tantalum or electrolytic capacitors at the lt3091 input in place of ceramic capacitors.stability and output capacitance the lt3091 requires an output capacitor for stability . it is stable with low esr capacitors ( such as ceramic , tantalum or low esr electrolytic ). a minimum output capacitor of 10f with an esr of 500m or less is recommended to prevent oscillations . larger values of output capacitance figure 2. guard ring layout for dfn stability and input capacitance the lt3091 is stable with a minimum of 10f capacitor placed at the in pin . low esr ceramic capacitors can be used. however , in cases where long wires connect the power supply to the lt3091s input and ground, the use of low value input capacitors combined with a large output load current may result in instability . the resonant lc tank circuit formed by the wire inductance and the input capaci - tor is the cause and not because of lt3091 instability. the self inductance , or isolated inductance , of a wire is directly proportional to its length . however , the wire diameter has less influence on its self inductance . for example, the self inductance of a 2- awg isolated wire with a diameter of 0 .26" is about half the inductance of a 3091 f02 out set 12 3 4 5 6 7 1413 12 11 10 98 15 in downloaded from: http:///
lt3091 16 3091fa for more information www.linear.com/lt3091 applications information decrease peak output deviations during a load transient . the lt3091 requires a minimum 20a load current to maintain stability under all operating conditions. give extra consideration to the use of ceramic capacitors . ceramic capacitors are manufactured with a variety of di - electrics, each with different behavior across temperature and applied voltage . the most common dielectrics used are specified with eia temperature characteristic codes of z5u, y5v , x5r and x7r . the z5u and y5v dielectrics are good for providing high capacitance in small packages , but they have strong voltage and temperature coefficients as shown in figures 3 and 4 . when used with a 5v regulator , a 16v 10f y5v capacitor can exhibit an effective value as low as 1f to 2f for the dc bias voltage applied over the operating temperature range. figure 3. ceramic capacitor dc bias characteristics figure 4. ceramic capacitor temperature characteristics the x5r and x7r dielectrics result in more stable character - istics, and are thus more suitable for use as the regulator s output capacitor . the x7r dielectric has better stability across temperature , while x5r is less expensive and is available in higher values . nonetheless , care must still be exercised when using x5r and x7r capacitors . the x5r and x7r codes only specify operating temperature range and the maximum capacitance change over temperature . while capacitance change due to dc bias for x5r and x7r is better than y5v and z5u dielectrics , it can still be significant enough to drop capacitance below sufficient levels. capacitor dc bias characteristics tend to improve as component case size increases , but verification of expected capacitance at the operating voltage is highly recommended. voltage and temperature coefficients are not the only sources of problems . some ceramic capacitors have a piezoelectric response . a piezoelectric device generates a voltage across its terminals due to mechanical stress upon it, similar to how a piezoelectric microphone works . for a ceramic capacitor the stress can be induced by mechanical vibrations within the system or due to thermal transients . output noise analysis the lt3091 offers many advantages with respect to noise performance. traditional linear regulators have several sources of noise . the most critical noise sources for an ldo are its voltage reference , the error amplifier , the noise of the resistors in the divider network setting output volt - age and the noise gain created by this resistor divider. many low noise regulators pin out the voltage reference to allow for bypassing and noise reduction of the refer - ence. unlike other linear regulators , the lt3091 does not use a traditional voltage reference , but instead it uses a 50a current source reference . that current operates with typical noise current levels of 31.6pa/ hz (10na rms over a 10hz to 100khz bandwidth ). the voltage noise equals the noise current multiplied by the resistor value . the resistor itself generates spot noise equal to 4ktr ( whereby k = boltzmann s constant , 1 .38 ? 10 C23 j / k and t is the absolute temperature ) which is rms summed with the reference current noise. dc bias voltage (v) 0 change in value (%) C20 0 20 6 10 3091 f03 C40 C60 2 4 8 12 14 16 C80 C100 both capacitors are 16v 1210 case size, 10f y5v x5r temperature (c) C50 change in value (%) C20 0 4020 25 75 3091 f04 C40 C60 C25 0 50 100 125 C80 C100 both capacitors are 16v 1210 case size, 10f y5v x5r downloaded from: http:///
lt3091 17 3091fa for more information www.linear.com/lt3091 applications information one problem that conventional linear regulators face is that the resistor divider setting v out gains up the refer - ence noise. in contrast, the lt3091s unity gain follower architecture presents no gain from the set pin to the output. therefore , output noise is virtually independent of the output voltage setting if a capacitor bypasses the set pin . resultant output noise is then set by the error amplifier s noise , typically 57nv/ hz (18v rms in a 10hz to 100khz bandwidth). curves in the typical performance characteristics sec - tion show noise spectral density and peak-to-peak noise characteristics for both the reference current and the error amplifier over a 10hz to 100khz bandwidth.set pin (bypass) capacitance : output noise , psrr , transient response and soft-start bypassing the set pin s voltage setting resistor with a capacitor lowers output noise . the typical performance characteristics section illustrates that connecting a 0.1f from set to gnd yields output noise as low as 18v rms . paralleling multiple lt3091 s further reduces noise by n , for n parallel regulators . curves in the typical performance characteristics section show noise spectral density and peak-to-peak noise characteristics for the error amplifier for different values of bypass capacitance. use of a set pin bypass capacitor also improves psrr and transient response performance . it is important to note that any bypass capacitor leakage deteriorates the lt3091s dc regulation. capacitor leakage of even 50na is a 0 .1% dc error . therefore , ltc recommends the use of a good quality low leakage capacitor. the final benefit of using a set pin bypass capacitor is that it soft starts the output and limits inrush current . the r-c time constant , formed by the set pin resistor and capacitor, controls soft-start time . ramp-up rate from 0 to 90% of nominal v out is: t ss 2.3 ? r set ? c set for applications requiring higher accuracy or an adjustable output voltage , the set pin may be actively driven by an external voltage source capable of sourcing 50a C the application limitations are the creativity and ingenuity of the circuit designer . for instance , connecting a precision voltage reference to the set pin removes any errors in output voltage due to the reference current and resistor tolerances. shutdown/uvlo the shdn pin is used to put the lt3091 into a micro- power shutdown state . the lt3091 has an accurate C1. 27v turn-on threshold on the shdn pin . this threshold can be used in conjunction with a resistor divider from the input supply to define an accurate undervoltage lockout (uvlo) threshold for the regulator . the shdn pin current ( at the threshold) needs to be considered when determining the resistor divider network . see the typical performance curves for shdn pin current vs shdn pin voltage. moreover, since the shdn pin is bidirectional , it can be taken beyond 1.4v to turn-on the lt3091. in bipolar supply applications , the positive shdn threshold can be used to sequence the turn-on of the lt3091 after the positive regulator has turned on.current monitoring (imonn and imonp) the lt3091 incorporates a precision positive or negative current monitor . as illustrated in the block diagram , the negative current monitor pin (imonn) sinks current pro - portional (1:2000) to the output current while the positive current monitor pin ( imonp ) sources current proportional (1: 4000 ) to the output current . for proper operation , ensure imonn is at least 2v above in and imonp. as highlighted in figure 5 , for a negative current monitor application, tie imonp to in and tie imonn through a figure 5: negative output current monitor lt3091 gnd 1mv per ma ilim shdn 3091 f05 i out 4000 imonn out set 10f in v in C3v to C10v imonp 10f v out : C2.5 max i out : 1.5a 5k 0.1f 49.9k 2k downloaded from: http:///
lt3091 18 3091fa for more information www.linear.com/lt3091 applications information the lt3091 s positive or negative current monitor circuitry remains accurate even under short circuit or dropout conditions. externally programmable current limit the ilim pin internally regulates to 225mv above in . connecting a resistor from ilim to in sets the current flowing out of the ilim pin , which in turn programs the lt3091 s current limit . the programming scale factor is 20k ? a . for example , a 40k resistor between ilim and in programs current limit to 500ma. for good accuracy , kelvin connect this resistor to the lt3091s in pin. in cases where the out-to-in differential is greater than 7v, the lt3091 s foldback circuitry decreases the internal current limit . therefore , internal current limit may over - ride the externally programmed current limit level to keep the lt3091 within its safe-operating-area (soa). see the internal current limit vs input-to-output differential graph in the typical performance characteristics section . ilim can be tied to in if external programmable current limit is not needed . however , because the ilim pin is internally regulated to 225mv above in , if ilim pin is shorted to in , then this loop current limits , causing the lt3091 s quiescent current to increase by about 300a. hence, when unused , it is recommended to tie ilim to in through a 5k resistor.load regulation the lt3091 does not have a separate kelvin connection for sensing output voltage . therefore , it is not possible to provide true remote load sensing . the connectivity resistance between the regulator and the load limits load regulation. the data sheet specification for load regulation is kelvin sensed at the out pin of the package . gnd side kelvin sensing is a true kelvin connection , with the top of the voltage setting resistor returned to the positive side of the load ( see figure 8 ). connected as shown , system load regulation is the sum of the lt3091 load regulation and the parasitic line resistance multiplied by the output current . it is therefore important to keep the negative connection between the regulator and the load as short as possible and to use wide wires or pc board traces. resistor to gnd C this generates a negative voltage (pro - portional to output current ) on imonn . furthermore , as illustrated in figure 6 , the negative current monitor pin can also be used for cable drop compensation . cable drop compensation corrects for load dependent voltage drop caused by a resistive connection between the lt3091s out pin and its load. figure 6. simple cable drop compensation figure 7. positive output current monitor for a positive current monitor application , as illustrated in figure 7 , tie imonp through a resistor to gnd this generates a positive voltage ( proportional to output cur - rent) on imonp . and tie imonn to a supply at least 2v above the maximum operating imonp voltage.when unused , imonn and imonp pins can be left floating ; however, this slightly reduces (~5%) the device s internal current limit . hence , if the current monitor functionality is not used , as shown in figure 1 , it is recommended to tie imonn to gnd and imonp to in. lt3091 r cbl = r cbl1 + r cbl2 set gnd ilim shdn 3091 f06 ? + 50a imonn out 0.1f 10f r cdc = r cbl ? 2k r set in v in ?C6v imonp 10f r cbl1 r cbl2 5k load lt3091 gnd 3.3v ilim 4k 1mv per ma shdn 3091 f07 i out 4000 imonn out set 10f in v in ?3v to ?10v imonp 10f v out : ?2.5v max i out : 1.5a 5k 0.1f 49.9k 0.1f downloaded from: http:///
lt3091 19 3091fa for more information www.linear.com/lt3091 applications information figure 8. connections for best load regulation figure 9. floating 3-terminal adjustable regulator it is important to note that in a floating configuration and with slow v in ramp-up and ramp-down ( as shown in figures 10 and 11 ), the lt3091 may exhibit oscillations during start-up if shdn is tied to v in . this occurs because the shdn comparator s turn-on and turn-off thresholds are referenced to the lt3091 s gnd pin . since , in floating configuration, the gnd pin of the lt3091 is tied to the out pin , which is slowly increasing as v in is ramping up , the reference point for the shdn comparator is changing ; hence, it causes start-up oscillations . this oscillation can be minimized by placing at least 0.1f and 47f capacitor at the set and out pins , respectively although it won t be eliminated , as per figures 10 and 11 below . for fast v in ramp-up and ramp-down , the lt3091 does not oscillate . if however , the shdn pin is tied to a positive supply , 1.3v and above ( as shown in figure 12 ), then there are no start-up oscillations and a 10 f minimum output capacitor can be used but having some set pin capacitance is still recommended . in addition to tying the gnd pin to the out pin ( for floating configuration ), the gnd pin of lt3091 can also be tied to a positive voltage as shown in the next section. figure 10. floating mode: input supply ramp-up floating 3-terminal regulator the lt3091 s rail-to-rail error amp allows the ldo to be configured as a floating three-terminal regulator . with proper protection , the lt3091 can be used in arbitrarily high voltage applications . figure 9 illustrates this configura - tion. in this mode , the gnd pin current is supplied by the load; hence , a minimum 2ma load current is required to maintain regulation . if true zero output voltage operation is required, return the 2ma load current to a positive supply . note that in three terminal operation , the minimum input voltage is now the device s dropout voltage . furthermore , the ilim pin is internally regulated to 225mv above in . this servo loop will current limit if ilim is shorted to in , thereby causing lt3091 s quiescent current to increase by about 300a. hence , when unused , it is recommended to tie ilim to in through a 5k resistor. figure 11. floating mode: input supply ramp-down v in : C5v to 0v c out : 15f, c set : 0.1f v out : C3v to 0v i l : 1.5a, shdn = in 1ms/div v in 2v/div v out 1v/div 3091 f11 v in : 0v to C5v c out : 15f, c set : 0.1f v out : 0v to C3v i l : 1.5a, shdn = in 10ms/div v in 2v/div v out 1v/div 3091f10 lt3091 v out C2.5vmax i out 1.5a parasitic resistance gnd ilim shdn 3091 f08 ? + 50a set out imonn c in 10f r set 49.9k in v in C3v to C10v imonp r p r p r p r ilim 5k load c out 10f lt3091 v out C15vmax i out 1.5a gnd ilim shdn 3091 f09 ? + 50a set out imonn c in 10f r set 301k in v in C17v to C22v imonp r ilim 5k c out 15f 0.1f downloaded from: http:///
lt3091 20 3091fa for more information www.linear.com/lt3091 applications information gnd pin versatility of lt3091 for applications requiring very low output voltages such as below C1v, the minimum input voltage of C1.9v limits how low v in can drop before the device stops regulating . as shown in figure 13 , this results in a much higher dropout voltage set by the minimum v in specification rather than the actual dropout of the npn pass device. set below the lt3091s C1.9v minimum input voltage . as long as there is 1.9v between in and gnd pins of lt3091, the minimum operating voltage is satisfied . now it can operate with much lower dropout voltage , with the device dropout set by the pass device as illustrated in figure 14 . figure 12. floating mode: input supply ramp-up and down using positive shdn bias voltage v in : C5v to 0v c out : 15f, c set : 0.1f v out : C3v to 0v i l : 1.5a, v shdn = 1.5v 50ms/div v in 2v/div v out 1v/div 3091 f12 figure 13. generating very low output voltages figure 14. low dropout operation for very low output voltages note that if the lt3091s shdn capability is not desired , then tie the shdn pin to v in . however , if it is desired to turn the device on and off , then the shdn logic signal needs to be referenced to the lt3091 s gnd pin . a simple way to achieve this is shown figure 15 , but the gnd pin needs to be at least +1.4v. figure 15. gnd pin referenced shdn signal a solution to this problem is available from the lt3091 architecture and the flexibility in how its gnd pin can be connected. the gnd pin does not need to be connected to system ground ! it can be connected to a positive volt- age as well . if the gnd pin of lt3091 is tied to a positive voltage that is at least 1.9v above v in , then v in can be lt3091 gnd ilim shdn ? + 50a set out imonn c in 10f r set 4.02k in v in C1.9v to C7v imonp 5k c out 10f v out C0.2vmax i out 1.5a r ilim 0.1f 3091 f13 lt3091 gnd ilim shdn ? + 50a set out imonn c in 10f r set 4.02k in v in C0.7v to C7v imonp 5k c out 10f +1.2v or higher v out C0.2vmax i out 1.5a r ilim 0.47f 0.1f 3091 f14 lt3091 gnd ilim shdn shdn (active low) ? + 50a set out imonn c in 10f r set 4.02k in v in C0.7v to C7v imonp 5k c out 10f +1.4v or higher v out C0.2vmax i out 1.5a r ilim 0.47f 0.1f 3091 f15 100k downloaded from: http:///
lt3091 21 3091fa for more information www.linear.com/lt3091 applications information in summary , the gnd pin of lt3091 is highly versatile and can be tied to different places depending on the ap - plication s requirements : a ) it can be tied to the system gnd for low dropout operation for output voltages greater than C1.6v, b ) it can be tied to a positive voltage for low dropout operation for very low output voltages , and c ) as illustrated in the floating 3- terminal regulator section , the gnd pin can be tied to the out pin for very high common mode voltage applications. direct paralleling higher output current is obtained by paralleling multiple lt3091s. tie all set pins together and all in pins together . connect the out pins together using small pieces of pc trace ( used as a ballast resistor ) to equalize the currents in each lt3091. pc trace resistance in m / inch is shown in table 2. ballasting requires only a tiny area. table 2. pc board trace resistance weight (oz) 10mil width* 20mil width* 1 54.3 27.1 2 27.1 13.6 *trace resistance is measured in m/in the small worst-case offset of 2mv for each paralleled lt3091 minimizes the value of required ballast resistance . figure 16 illustrates that two lt3091s, each using a 10m pcb trace ballast resistor , provide better than 80 % output current sharing at full load . the 10m external resistances (5m for the two devices in parallel ) only adds 15mv of output regulation drop with a 3a maximum load . with an output voltage as low as C1.5v, this only adds 1 % to the regulation accuracy . if this additional load regulation error is intolerable , circuits shown in the typical applications section highlight how to correct this error using the output current monitor function or a master-slave configuration . finally, note that more than two lt3091 s can be paralleled for higher output current . paralleling multiple lt3091 s is a useful technique for distributing heat on the pcb . for applications with high input-to-output voltage differential , either input series resistors or resistors in parallel with the lt3091s further spread heat. thermal considerations the lt3091 has internal power and thermal limiting cir - cuitry designed to protect it under overload conditions . the typical thermal shutdown temperature is 165 c with about 8 c of hysteresis . for continuous normal load conditions , do not exceed the maximum junction temperature . it is important to consider all sources of thermal resistance from junction to ambient . this includes junction-to-case , case-to-heat sink interface , heat sink resistance or circuit board-to-ambient as the application dictates . additionally , consider all heat sources in close proximity to the lt3091. the undersides of the dfn and tssop packages have exposed metal from the lead frame to the die attachment . both packages allow heat to directly transfer from the die junction to the pcb metal to limit the maximum operating figure 16. parallel devices lt3091 v out C2.5vmax i out 3a gnd ilim shdn ? + 50a set out imonn 22f 24.9k in v in C3v to C10v imonp 5k 22f 10m 0.1f 3091 f16 lt3091 gnd ilim shdn ? + 50a set out imonn in imonp 5k 10m downloaded from: http:///
lt3091 22 3091fa for more information www.linear.com/lt3091 applications information junction temperature . the dual-in-line pin arrangement allows metal to extend beyond the ends of the package on the topside ( component side ) of the pcb . connect this metal to in on the pcb . the multiple in and out pins of the lt3091 further assist in spreading heat to the pcb. for surface mount devices , heat sinking is accomplished by using the heat spreading capabilities of the pcb and its copper traces . copper board stiffeners and plated through- holes can also be used to spread the heat generated by power devices. table 3. measured thermal resistance for dfn package copper area board area thermal resistance top side* bottom side 2500mm 2 2500mm 2 2500mm 2 21c/w 1000mm 2 2500mm 2 2500mm 2 24c/w 225mm 2 2500mm 2 2500mm 2 28c/w 100mm 2 2500mm 2 2500mm 2 32c/w *device is mounted on topside table 4. measured thermal resistance for tssop package copper area board area thermal resistance top side* bottom side 2500mm 2 2500mm 2 2500mm 2 20c/w 1000mm 2 2500mm 2 2500mm 2 23c/w 225mm 2 2500mm 2 2500mm 2 26c/w 100mm 2 2500mm 2 2500mm 2 30c/w *device is mounted on topside table 5. r package, 7-lead dd-pak package copper area board area thermal resistance (junction-to- ambient) t op side* bottom side 2500mm 2 2500mm 2 2500mm 2 13c/w 1000mm 2 2500mm 2 2500mm 2 14c/w 225mm 2 2500mm 2 2500mm 2 16c/w *device is mounted on topside t7 package , 7- lead to-220 thermal resistance (junc- tion-to-case) = 3c/w tables 3 to 5 list thermal resistance as a function of copper area in a fixed board size . all measurements were taken in still air on a 4 layer fr-4 board with 1oz solid internal planes and 2oz top / bottom external trace planes with a total board thickness of 1. 6mm . the four layers were electrically isolated with no thermal vias present . pcb layers , copper weight, board layout and thermal vias affect the resultant thermal resistance . for more information on thermal resistance and high thermal conductivity test boards , refer to jedec standard je sd51, notably je sd51 -7 and jesd51-12 . achieving low thermal resistance necessitates attentions to detail and careful pcb layout. calculating junction temperature example: given an output voltage of C2.5v and input volt - age of C3.3v 5 %, output current range from 1ma to 1a, and a maximum ambient temperature of 85 c, what is the maximum junction temperature?the lt3091s power dissipation is: i out(max) ? (v in(max) C v out ) + i gnd ? v in(max) where: i out(max) = C1a v in(max) = C3.465v i gnd (at i out = C1a and v in = C3.465v) = C15ma thus: p = (C1a) ? (C3.465v + 2.5v) + (C15ma) ? (C 3.465v) = 1.02w using a dfn package , the thermal resistance is in the range of 21 c/ w to 32 c/ w depending on the copper area . therefore, the junction temperature rise above ambient approximately equals: 1.02w ? 27c/w = 27.5c the maximum junction temperature equals the maxi- mum ambient temperature plus the maximum junction temperature rise above ambient: t jmax = 85c + 27.5c = 112.5c downloaded from: http:///
lt3091 23 3091fa for more information www.linear.com/lt3091 applications information overload recovery like many monolithic power regulators , the lt3091 in - corporates safe-operating-area ( soa ) protection . the soa protection activates at output-to-input differential voltage greater than 7v. the soa protection decreases current limit as the output-to-input differential increases and keeps the power transistor inside a safe operating region for all values of output-to-input voltage up to the lt3091s absolute maximum ratings . the lt3091 provides some level of output current for all values of output-to-input differential. refer to the current limit curve in the typical performance characteristics section . when power is first applied and input voltage rises , the output follows the input and keeps the output-to-input differential low to allow the regulator to supply large output current and startup into high current loads. due to current limit fold back , however , at high input volt - ages, a problem can occur if the output voltage is low and the load current is high . such situations occur after the removal of a short-circuit or if the shutdown pin is pulled high after the input voltage has already turn on . the load line for such a load intersects the output current curve at two points . if this happens , the regulator has two stable output operating points . with this double intersection , the input power supply may need to be cycled down to zero and brought back up again to make the output recover . other ltc negative linear regulators such as the lt3015, lt1964, and lt1175 also exhibit this phenomenon , so it is not unique to the lt3091.protection features the lt3091 incorporates several protection features that make it ideal for use in battery-powered applications . in addition to the normal protection features associated with monolithic regulators , such as current limiting and thermal limiting , the device also protects itself against reverse output voltages.precision current limit and thermal overload protection protect the lt3091 against overload and fault conditions at the device s output . for normal operation , do not al - low the junction temperature to exceed 125 c for e- and i-grades and 150 c for h- and mp-grades. pulling the lt3091 s output above ground induces no damage to the part . if in is left open circuited or grounded , out can be pulled 36v above gnd . in this condition , a maximum current of 7ma flows into the out pin and out of the gnd pin . if in is powered by a voltage source , out sinks the lt3091s ( fold back ) short-circuit current and protects itself by thermal limiting . in this case , however , grounding the shdn pin turns off the device and stops out from sinking the short-circuit current. downloaded from: http:///
lt3091 24 3091fa for more information www.linear.com/lt3091 parallel devices typical applications lt3091 v out C2.5vmax i out 3a gnd ilim shdn ? + 50a set out imonn 22f 24.9k1% in v in C3v to C10v imonp 5k 22f 10m 0.1f 3091 ta02 lt3091 gnd ilim shdn ? + 50a set out imonn in imonp 5k 10m downloaded from: http:///
lt3091 25 3091fa for more information www.linear.com/lt3091 typical applications paralleling devices using imonn to cancel ballast resistor drop load sharing without ballasting (using imonp) master regulator slave regulator lt3091 v out C2.5vmax i out 3a gnd ilim shdn ? + 50a set out imonn 22f 24.9k1% in v in C3v to C10v imonp 5k r blst 10m c set 0.1f 3091 ta03 lt3091 gnd ilim shdn ? + 50a set out imonn in imonp 5k r comp 10 r comp = 2k ? rblst/n v out = n ? 50a(r set + r comp ) n = number of lt3091s in parallel r blst 10m 22f lt3091 gnd ilim shdn set out imonn 22f 49.9k1% in v in C3v to C10v imonp 5k 3091 ta04 0.1f lt3091 gnd ilim shdn set imonn v out : C2.5v max i out : 3a in imonp 5k 300 300 2n3904 2n3904 0.1f 22f 49.9k1% ? + 50a ? + 50a out downloaded from: http:///
lt3091 26 3091fa for more information www.linear.com/lt3091 paralleling devices without ballasting (50ma minimum load) using lower value rset for higher output voltages typical applications lt3091 gnd ilim shdn ? + 50a set out imonn 22f 49.9k1% master regulator slave regulator in v in C3v to C10v imonp 5k 20 0.1f 22f 3091 ta05 lt3091 gnd set ilim shdn ? + 50a out imonn in imonp 5k v out C2.5vi out 3a 20m lt3091 gnd ilim shdn ? + 50a set out imonn c in 10f 10k1% r set in v in imonp 5k 0.1f c out 10f 3091 ta06 v out = C0.5v C 1ma ? r set max i out : 1.5a 5231% downloaded from: http:///
lt3091 27 3091fa for more information www.linear.com/lt3091 constant-current constant-voltage lab power supply low dropout operation for very low output voltages typical applications lt3091 gnd ilim shdn 3091 ta07 ? + 50a set 0.1f out imonn 10f r set v out in v in imonp r ilim 10f lt3091 gnd ilim shdn ? + 50a set out imonn c in 10f 4.02k1% in v in C0.7v to C7v imonp 5k 0.1f c out 10f 3091 ta08 v out : C0.2v max i out : 1.5a +1.2v or higher c gnd 0.47f downloaded from: http:///
lt3091 28 3091fa for more information www.linear.com/lt3091 input supply tracking floating 3-terminal regulator (for arbitrarily high voltage applications) typical applications lt3091 gnd ilim shdn 3091 ta09 ? + 50a set 0.1f out imonn 10f 100k1% v out = v in C 5v max i out 1.5a v in in imonp 5k 10f lt3091 gnd ilim 36v 36v shdn 3091 ta10 ? + 50a set 0.1f out imonn 10f v in C52v to C57v 1m1% v out C50v max i out 1.5a in imonp 5k 10f downloaded from: http:///
lt3091 29 3091fa for more information www.linear.com/lt3091 500ma led driver with grounded led tab (heatsink) 500ma led driver with positive supply low noise single inductor positive-to-negative converter typical applications lt3091 gnd ilim shdn 3091 ta11 ? + 50a set out imonn 10f v in 400m 10f in imonp 5k 4.02k 500ma v in gnd ilim shdn 3091 ta12 ? + 50a lt3091 set out imonn 10f 400m 10f in imonp 5k 4.02k 500ma lt3091 gnd ilim shdn 3091 ta13 ? + 50a set 0.1f out imonn 10f 1206 49.9k1% v out2 C2.5vmax i out 1.5a in imonp 5k 10f1206 v in 12v 100k 60.4k 124k c1 22f 3.3nf 0.1f c322f 6.8k v out C5v 1.5a c2 1f sw1 sw2 fb clkout gate v c ss v in rt gnd sync fault shdn lt3581 56pf c1: 22f, 25v, x7r, 1210 c2: 1f, 50v, x7r, 1206 c3: 22f, 16v, x7r, 1210 d1: central cmsh3-40fl l1, l2: coilcraft msd7342-332mlb l2 3.3h d1 l1 3.3h ? ? downloaded from: http:///
lt3091 30 3091fa for more information www.linear.com/lt3091 high efficiency low noise single inductor positive-to-negative converter with ldo input-to-output control typical applications lt3091 gnd ilim shdn 3091 ta14 set 0.1f 10f out imonp 1m v out C2.5vmax i out 1.5ma in imonn lt8612 v in run/ssync pg tr/ss r t gnd pgnd intv cc bias bst sw fb l: coilcraft xal5030-222me v in 12v v out C 2v 49.9k 4.99k 1m 143k l 2.2h 60.4k 1m 1nf 1f 10pf 347f 10f downloaded from: http:///
lt3091 31 3091fa for more information www.linear.com/lt3091 12v to 3.3v low noise power supply typical applications 3091 ta15 lt3081 in set out 22f v out1 3.3vmax i out 1.5a temp i lim i mon lt3091 gnd ilim shdn ? + 50a i set 50a set 0.1f out imonn 10f 66.5k1% v out2 C3.3vmax i out 1.5a in imonp 5k 0.1f 66.5k1% 22f C5v 5v 10f ? + swb2 swa2 swb1 swa1 lt8582 pg1sync1 clkout1 clkout2 100k sync2pg2 v in2 shdn2 v in1 shdn1 v c1 ss1 rt1 gnd rt2 ss2 gate2 v c2 fbx2 fbx1 gate1 v in 12v 0.1f 0.1f 1.5nf 47pf47pf 18.7k 13k 100k 60.4k l3 4.7h ? l1 4.7h l24.7h 2.2nf 45.3k c out2 22f2 c out1 22f2 115k115k c in2 22f c in1 , c in2 : 22f, 25v, x7r, 1210 c out1 , c out2 : 22f, 16v, x7r, 1210 c 1 , c 2 : 2.2f, 50v, x7r, 1206 d1, d2: central cmsh3-40fl l1, l2: wrth we tdc 74489440047 l3, l4: wrth we tdc 74489440047 c1 2.2f d1 c in1 22f d2 ? ? l4 4.7h ? c2 2.2f downloaded from: http:///
lt3091 32 3091fa for more information www.linear.com/lt3091 reference buffer coincident tracking supplies typical applications 3091 ta17 lt3091 gnd ilim shdn ? + 50a set r149.9k 1% out imonn c in 22f v out1 , C2.5v 1.5a v out2 , C3.3v 1.5a v out3 , C5v 1.5a in imonp 5k c out 10f v in C5.5v to C10v lt3091 gnd ilim shdn ? + 50a set out imonn in imonp 5k c out 10f lt3091 gnd ilim shdn ? + 50a set out imonn in imonp 5k c out 10f r334k 1% r216.2k 1% 3091 ta16 lt3091 gnd ilim shdn ? + 50a set lt1004-2.5 out imonn c in 10f v out C2.5vmax i out 1.5a in imonp 5k c out 10f v in C3v to C10v downloaded from: http:///
lt3091 33 3091fa for more information www.linear.com/lt3091 low noise 4-quadrant power supply simple cable drop compensation typical applications 3091 ta18 lt3091 gnd ilim shdn ? + 50a set 0.1f out imonn 10f 100k1% v out C5vmax i out 1.5a in imonp 5k r cdc = r cbl ? 2k v in C6v r cbl = r cbl1 + r cbl2 10f r cbl1 r cbl2 load 3091 ta19 10f lt3081 ctrl v cc ? + set out in 22f opt lt3091 gnd ilim shdn ? + 50a set out imonn 10f v out (source/sink 1.5a) v ee + v dropout (l t3091) v out v cc C v dropout (lt3081) v set in imonp 5k 14m 14m v ee 10f 10f 50a i lim temp imon downloaded from: http:///
lt3091 34 3091fa for more information www.linear.com/lt3091 2-terminal current source positive output current monitor negative output current monitor typical applications v in gnd ilim shdn 3091 ta20 ? + 50a lt3091 set out imonn i out = 200mv/r1 in imonp 5k 10f 4.02k, 1% r1 gnd ilim shdn 3091 ta21 ? + 50a lt3091 set out imonp v out C2.5vmax i out 1.5a in imonn 5k 10f 49.9k1% 10f 0.1f 3v 0.1f 2.67k to adc v in C3v to C10v gnd imonp ilim shdn 3091 ta22 ? + 50a lt3091 set out imonn v out C2.5vmax i out 1.5a in 10f 5k 49.9k1% 10f 0.1f to adc 1.33k v in C3v to C10v downloaded from: http:///
lt3091 35 3091fa for more information www.linear.com/lt3091 3.00 0.10 (2 sides) 4.00 0.10 (2 sides) note:1. drawing proposed to be made variation of version (wged-3) in jedec package outline mo-229 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.40 0.10 bottom viewexposed pad 1.70 0.10 0.75 0.05 r = 0.115 typ r = 0.05 typ 3.00 ref 1.70 0.05 1 7 14 8 pin 1 top mark (see note 6) 0.200 ref 0.00 C 0.05 (de14) dfn 0806 rev b pin 1 notchr = 0.20 or 0.35 45 chamfer 3.00 ref recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 2.20 0.05 0.70 0.05 3.60 0.05 packageoutline 0.25 0.05 0.25 0.05 0.50 bsc 3.30 0.05 3.30 0.10 0.50 bsc de package 14-lead plastic dfn (4mm 3mm) (reference ltc dwg # 05-08-1708 rev b) package description please refer to http:// www .linear.com/product/lt3091#packaging for the most recent package drawings. downloaded from: http:///
lt3091 36 3091fa for more information www.linear.com/lt3091 fe16 (bc) tssop rev k 1013 0.09 C 0.20 (.0035 C .0079) 0 C 8 0.25 ref 0.50 C 0.75 (.020 C .030) 4.30 C 4.50* (.169 C .177) 1 3 4 5 6 7 8 10 detail b is the part of the lead frame feature for reference only no measurement purpose 9 4.90 C 5.10* (.193 C .201) 16 1514 13 12 11 1.10 (.0433) max 0.05 C 0.15 (.002 C .006) 0.65 (.0256) bsc 2.94 (.116) 0.48 (.019) ref 0.51 (.020) ref 0.195 C 0.30 (.0077 C .0118) typ 2 recommended solder pad layout 0.45 0.05 0.65 bsc 4.50 0.10 6.60 0.10 1.05 0.10 2.94 (.116) 3.58 (.141) 3.58 (.141) millimeters (inches) *dimensions do not include mold flash. mold flash shall not exceed 0.150mm (.006") per side note:1. controlling dimension: millimeters 2. dimensions are in 3. drawing not to scale 4. recommended minimum pcb metal size for exposed pad attachment see note 4 see note 5 5. bottom exposed paddle may have metal protrusion in this area. this region must be free of any exposed traces or vias on pcb layout 6.40 (.252) bsc fe package 16-lead plastic tssop (4.4mm) (reference ltc dwg # 05-08-1663 rev k) exposed pad variation bc detail b 4.60 package description please refer to http:// www .linear.com/product/lt3091#packaging for the most recent package drawings. downloaded from: http:///
lt3091 37 3091fa for more information www.linear.com/lt3091 r (dd7) 0212 rev f .026 C .035 (0.660 C 0.889) typ .143 +.012C.020 ( ) 3.632 +0.305C0.508 .050 (1.27) bsc .013 C .023 (0.330 C 0.584) .095 C .115 (2.413 C 2.921) .004 +.008C.004 ( ) 0.102 +0.203C0.102 .050 .012 (1.270 0.305) .059 (1.499) typ .045 C .055 (1.143 C 1.397) .165 C .180 (4.191 C 4.572) .330 C .370 (8.382 C 9.398) .060 (1.524) typ .390 C .415 (9.906 C 10.541) 15 typ .420 .350 .585 .090 .035 .050 .325 .205 .080 .585 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 rev f) detail a detail a 0 C 7 typ 0 C 7 typ package description please refer to http:// www .linear.com/product/lt3091#packaging for the most recent package drawings. downloaded from: http:///
lt3091 38 3091fa for more information www.linear.com/lt3091 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 . .050 (1.27) .026 C .036 (0.660 C 0.914) t7 (to-220) 0801 .135 C .165 (3.429 C 4.191) .700 C .728 (17.780 C 18.491) .045 C .055 (1.143 C 1.397) .165 C .180 (4.191 C 4.572) .095 C .115 (2.413 C 2.921) .013 C .023 (0.330 C 0.584) .620 (15.75) typ .155 C .195* (3.937 C 4.953) .152 C .202 (3.860 C 5.130) .260 C .320 (6.604 C 8.128) .147 C .155 (3.734 C 3.937) dia .390 C .415 (9.906 C 10.541) .330 C .370 (8.382 C 9.398) .460 C .500 (11.684 C 12.700) .570 C .620 (14.478 C 15.748) .230 C .270 (5.842 C 6.858) bsc seating plane *measured at the seating plane t7 package 7-lead plastic to-220 (standard) (reference ltc dwg # 05-08-1422) package description please refer to http:// www .linear.com/product/lt3091#packaging for the most recent package drawings. downloaded from: http:///
lt3091 39 3091fa for more information www.linear.com/lt3091 revision history rev date description page number a 03/16 revised output offset voltage v os conditions and specs 3 downloaded from: http:///
lt3091 40 3091fa for more information www.linear.com/lt3091 ? linear technology corporation 2015 lt 0316 rev a ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/lt3091 related parts typical application part number description comments lt1185 3a, negative linear regulator 750mv dropout voltage, v in = C4.3v to C35v, dd-pak and to-220 packages lt1175 500ma, negative low dropout micropower regulator 500mv dropout voltage, v in = C4.5v to C20v, n8, s8, dd-pak, to-220 and sot-223 lt1964 200ma, negative low noise low dropout regulator 340mv dropout voltage, low noise: 30v rms , v in = C1.9v to C20v, dfn and sot-23 packages lt3015 1.5a, fast transient response, negative ldo regulator 310mv dropout voltage, low noise: 60v rms , v in = C2.3v to C30v, dfn, msop, to-220 and dd-pak packages lt3080 1.1a, parallelable, low noise, low dropout linear regulator 350mv dropout v oltage (2-supply operation), low noise: 40v rms , v in : 1.2v to 36v, single resistor output, dfn, msop, to-220, dd and sot-223 packages lt3085 500ma, parallelable, low noise, low dropout linear regulator 275mv dropout voltage (2-supply operation), low noise: 40v rms , v in : 1.2v to 36v, single resistor output, dfn, msop lt3082 200ma, parallelable, low noise, low dropout linear regulator low noise: 33v rms , v in : 1.2v to 40v, single resistor output, dfn, sot-223 and sot-23 packages lt3081 1.5a, parallelable, low noise, low dropout linear regulator low noise: 27v rms , v in : 1.2v to 36v, single resistor output, dfn, fe, dd-pak and to-220 packages lt3083 3a, parallelable, low noise, low dropout linear regulator 310mv dropout v oltage (2-supply operation), low noise: 40v rms , v in : 1.2v to 23v, single resistor output, dfn, tssop, to-220 and dd packages lt3090 C36v, 600ma negative linear regulator with programmable current limit 300mv dropout voltage, low noise: 18v rms , v in : C1.5v to C36v, single resistor output, dfn and msop packages parallel devices v in C3v to C10v gnd ilim shdn ? + 50a lt3091 set out imonn v out C2.5vmax i out 3a in imonp 5k 22f ilim shdn imonp 5k 24.9k1% 22f 0.1f 10m 10m gnd 3091 ta23 ? + 50a lt3091 set out imonn in downloaded from: http:///

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