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lt1129/lt1129-3.3/lt1129-5 1 112935ff typical application description micropower low dropout regulators with shutdown the lt ? 1129/lt1129-3.3/lt1129-5 are micropower low dropout regulators with shutdown. the devices are capable of supplying 700ma of output current with a dropout voltage of 400mv at maximum output. designed for use in battery-powered systems, the low quiescent current, 50a operating and 16a in shutdown, make them an ideal choice. the quiescent current does not rise in dropout as it does with many other low dropout pnp regulators. other features of the lt1129 /lt1129-3.3/lt1129-5 include the ability to operate with small output capacitors. they are stable with only 3.3f on the output while most older devices require between 10f and 100f for stability. also the input may be connected to ground or a reverse voltage without reverse current ? ow from output to input. this makes the lt1129/lt1129-3.3/lt1129-5 ideal for backup power situations where the output is held high and the input is at ground or reversed. under these conditions, only 16a will ? ow from the output pin to ground. the devices are available in 5-lead to-220, 5-lead dd-pak and 3-lead sot-223 packages. features applications n 400mv dropout voltage n 700ma output current n 50a quiescent current n no protection diodes needed n adjustable output from 3.8v to 30v n 3.3v and 5v fixed output voltages n controlled quiescent current in dropout n shutdown n 16a quiescent current in shutdown n stable with 3.3f output capacitor n reverse battery protection n no reverse output current n thermal limiting n surface mount sot-223 and dd-pak packages n low current regulator n regulator for battery-powered systems n post regulator for switching supplies n 5v to 3.3v logic regulator 5v supply with shutdown in out lt1129-5 gnd 5v out 500ma v in > 5.5v 3.3f solid tantalum + sense 112935 ta01 v shdn (pin 4) < 0.25 > 2.8 nc output off on on shdn 1 2 3 4 5 output current (a) 0 dropout voltage (v) 0.4 0.5 0.6 0.3 0.5 0.3 0.2 0.1 0.2 0.4 0.6 0.7 0.1 0 112935 ta02 dropout voltage l , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners.
lt1129/lt1129-3.3/lt1129-5 2 112935ff absolute maximum ratings input voltage ...................................................... 30v* output pin reverse current ................................. 10ma sense pin current ................................................ 10ma adjust pin current ................................................ 10ma sense pin, adjust pin reverse voltage ............... C 0.6v shutdown pin input voltage (note 2) ......... 6.5v, C 0.6v shutdown pin input current (note 2) .................. 20ma output short-circuit duration .......................... inde? nite (note 1) storage temperature range .................. C 65c to 150c operating junction temperature range (note 3) lt1129c-x .......................................... 0c to 125c lt1129c-x extended temperature range (note 12) ....................................... C40c to 125c lt1129i-x(note 12) ......................... C40c to 125c lt1129mp-x(note 12) ..................... C55c to 125c lead temperature (soldering, 10 sec) .................. 300c * for applications requiring input voltage ratings greater than 30v, contact the factory. 1 2 3 4 5 6 7 8 9 10 top view f package 20-lead plastic tssop 20 19 18 17 16 15 14 13 12 11 gnd gnd gnd gnd gnd gnd out sense gnd gnd gnd gnd gnd gnd gnd gnd in shdn gnd gnd note: all ground pins are internally connected ja = 40c/w obsolete package q package 5-lead plastic dd front view v in shdn gnd sense/adj* output 5 4 3 2 1 tab is gnd *pin 2 = sense for lt1129-3.3/lt1129-5 = adj for lt1129 ja = 30c/w 1 2 3 4 8 7 6 5 top view output gnd nc s8 package 8-lead plastic so v in gnd gnd shdn sense/ adj* *pin 2 = sense for lt1129-3.3/lt1129-5 = adj for lt1129 ja = 60c/w 3 2 1 front view tab is gnd st package 3-lead plastic sot-223 output gnd v in ja = 50c/w t package 5-lead plastic to-220 v in shdn gnd sense/adj* output front view 5 4 3 2 1 tab is gnd *pin 2 = sense for lt1129-3.3/lt1129-5 = adj for lt1129 ja = 50c/w pin configuration lead free finish tape and reel part marking* package description temperature range lt1129cs8#pbf lt1129cs8#trpbf 1129 8-lead plastic so 0c to 125c lt1129is8#pbf lt1129is8#trpbf 1129i 8-lead plastic so C40c to 125c lt1129cs8-3.3#pbf lt1129cs8-3.3#trpbf 11293 8-lead plastic so 0c to 125c lt1129is8-3.3#pbf lt1129is8-3.3#trpbf 1129i3 8-lead plastic so C40c to 125c lt1129cs8-5#pbf lt1129cs8-5#trpbf 11295 8-lead plastic so 0c to 125c order information
lt1129/lt1129-3.3/lt1129-5 3 112935ff order information lead free finish tape and reel part marking* package description temperature range lt1129is8-5#pbf lt1129is8-5#trpbf 1129i5 8-lead plastic so C40c to 125c lt1129cst-3.3#pbf lt1129cst-3.3#trpbf 11293 3-lead plastic sot-223 0c to 125c lt1129ist-3.3#pbf lt1129ist-3.3#trpbf 129i3 3-lead plastic sot-223 C40c to 125c lt1129mpst-3.3#pbf lt1129mpst-3.3#trpbf 129mp3 3-lead plastic sot-223 C55c to 125c lt1129cst-5#pbf lt1129cst-5#trpbf 11295 3-lead plastic sot-223 0c to 125c lt1129ist-5#pbf lt1129ist-5#trpbf 129i5 3-lead plastic sot-223 C40c to 125c lt1129cq#pbf lt1129cq#trpbf lt1129cq 5-lead plastic dd-pak 0c to 125c lt1129iq#pbf lt1129iq#trpbf lt1129iq 5-lead plastic dd-pak C40c to 125c lt1129cq-3.3#pbf lt1129cq-3.3#trpbf lt1129cq-3.3 5-lead plastic dd-pak 0c to 125c lt1129iq-3.3#pbf lt1129iq-3.3#trpbf lt1129iq-3.3 5-lead plastic dd-pak C40c to 125c lt1129cq-5#pbf lt1129cq-5#trpbf lt1129cq-5 5-lead plastic dd-pak 0c to 125c lt1129iq-5#pbf lt1129iq-5#trpbf lt1129iq-5 5-lead plastic dd-pak C40c to 125c lt1129ct#pbf lt1129ct#trpbf lt1129ct 5-lead plastic to-220 0c to 125c lt1129it#pbf lt1129it#trpbf lt1129it 5-lead plastic to-220 C40c to 125c lt1129ct-3.3#pbf lt1129ct-3.3#trpbf lt1129ct-3.3 5-lead plastic to-220 0c to 125c lt1129it-3.3#pbf lt1129it-3.3#trpbf lt1129it-3.3 5-lead plastic to-220 C40c to 125c lt1129ct-5#pbf lt1129ct-5#trpbf lt1129ct-5 5-lead plastic to-220 0c to 125c lt1129it-5#pbf lt1129it-5#trpbf lt1129it-5 5-lead plastic to-220 C40c to 125c lead based finish tape and reel part marking* package description temperature range lt1129cs8 lt1129cs8#tr 1129 8-lead plastic so 0c to 125c lt1129is8 lt1129is8#tr 1129i 8-lead plastic so C40c to 125c lt1129cs8-3.3 lt1129cs8-3.3#tr 11293 8-lead plastic so 0c to 125c lt1129is8-3.3 lt1129is8-3.3#tr 1129i3 8-lead plastic so C40c to 125c lt1129cs8-5 lt1129cs8-5#tr 11295 8-lead plastic so 0c to 125c lt1129is8-5 lt1129is8-5#tr 1129i5 8-lead plastic so C40c to 125c lt1129cst-3.3 lt1129cst-3.3#tr 11293 3-lead plastic sot-223 0c to 125c lt1129ist-3.3 lt1129ist-3.3#tr 129i3 3-lead plastic sot-223 C40c to 125c lt1129mpst-3.3 lt1129mpst-3.3#tr 129mp3 3-lead plastic sot-223 C55c to 125c lt1129cst-5 lt1129cst-5#tr 11295 3-lead plastic sot-223 0c to 125c lt1129ist-5 lt1129ist-5#tr 129i5 3-lead plastic sot-223 C40c to 125c lt1129cq lt1129cq#tr lt1129cq 5-lead plastic dd-pak 0c to 125c lt1129iq lt1129iq#tr lt1129iq 5-lead plastic dd-pak C40c to 125c lt1129cq-3.3 lt1129cq-3.3#tr lt1129cq-3.3 5-lead plastic dd-pak 0c to 125c lt1129iq-3.3 lt1129iq-3.3#tr lt1129iq-3.3 5-lead plastic dd-pak C40c to 125c lt1129cq-5 lt1129cq-5#tr lt1129cq-5 5-lead plastic dd-pak 0c to 125c lt1129iq-5 lt1129iq-5#tr lt1129iq-5 5-lead plastic dd-pak C40c to 125c lt1129ct lt1129ct#tr lt1129ct 5-lead plastic to-220 0c to 125c lt1129it lt1129it#tr lt1129it 5-lead plastic to-220 C40c to 125c lt1129ct-3.3 lt1129ct-3.3#tr lt1129ct-3.3 5-lead plastic to-220 0c to 125c lt1129it-3.3 lt1129it-3.3#tr lt1129it-3.3 5-lead plastic to-220 C40c to 125c
lt1129/lt1129-3.3/lt1129-5 4 112935ff symbol conditions min typ max units regulated output voltage (notes 4, 12) lt1129-3.3 v in = 3.8v, i out = 1ma, t j = 25c 4.3v < v in < 20v, 1ma < i out < 700ma l 3.250 3.200 3.300 3.300 3.350 3.400 v v lt1129-5 v in = 5.5v, i out = 1ma, t j = 25c 6v < v in < 20v, 1ma < i out < 700ma l 4.925 4.850 5.000 5.000 5.075 5.150 v v lt1129 (note 5) v in = 4.3v, i out = 1ma, t j = 25c 4.8v < v in < 20v, 1ma < i out < 700ma l 3.695 3.640 3.750 3.750 3.805 3.860 v v line regulation (note 12) lt1129-3.3 v in = 4.8v to 20v, i out = 1ma l 1.5 10 mv lt1129-5 v in = 5.5v to 20v, i out = 1ma l 1.5 10 mv lt1129 (note 5) v in = 4.3v to 20v, i out = 1ma l 1.5 10 mv load regulation (note 12) lt1129-3.3 i load = 1ma to 700ma, t j = 25c i load = 1ma to 700ma l 6 15 20 30 mv mv lt1129-5 i load = 1ma to 700ma, t j = 25c i load = 1ma to 700ma l 6 20 20 30 mv mv lt1129 (note 5) i load = 1ma to 700ma, t j = 25c i load = 1ma to 700ma l 6 15 20 30 mv mv dropout voltage (note 6) i load = 10ma, t j = 25c i load = 10ma l 0.13 0.20 0.25 v v i load = 100ma, t j = 25c i load = 100ma l 0.25 0.35 0.45 v v i load = 500ma, t j = 25c i load = 500ma l 0.37 0.45 0.60 v v i load = 700ma, t j = 25c i load = 700ma l 0.45 0.55 0.70 v v ground pin current (note 7) i load = 0ma l 50 70 a i load = 10ma l 310 450 a i load = 100ma l 2.0 3.5 ma i load = 300ma l 10 20 ma i load = 500ma l 25 45 ma i load = 700ma l 50 90 ma adjust pin bias current (notes 5, 8) t j = 25c 150 300 na shutdown threshold v out = off to on v out = on to off l l 0.25 1.2 0.75 2.8 v v shutdown pin current (note 9) v shdn = 0v l 610 a quiescent current in shutdown (note 10) v in = 6v, v shdn = 0v l 15 25 a order information lead based finish tape and reel part marking* package description temperature range lt1129ct-5 lt1129ct-5#tr lt1129ct-5 5-lead plastic to-220 0c to 125c lt1129it-5 lt1129it-5#tr lt1129it-5 5-lead plastic to-220 ?40c to 125c 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. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel speci? cations, go to: http://www.linear.com/tapeandreel/ electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c.
lt1129/lt1129-3.3/lt1129-5 5 112935ff electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. symbol conditions min typ max units ripple rejection v in C v out = 1v (avg), v ripple = 0.5v p-p , f ripple = 120hz, i load = 0.7a, t j = 25c 52 64 db current limit v in C v out = 7v, t j = 25c 1.2 1.6 a input reverse leakage current v in = C20v, v out = 0v l 1.0 ma reverse output current (note 11) lt1129-3.3 v out = 3.3v, v in = 0v lt1129-5 v out = 5v, v in = 0v lt1129 (note 5) v out = 3.8v, v in = 0v 16 16 16 25 25 25 a a a voltage will be equal to (v in C v dropout ). dropout voltage is measured between the input pin and the output pin. external voltage drops between the output pin and the sense pin will add to the dropout voltage. note 7: ground pin current is tested with v in = v out (nominal) and a current source load. this means that the device is tested while operating in its dropout region. this is the worst case ground pin current. the ground pin current will decrease slightly at higher input voltages. note 8: adjust pin bias current ? ows into the adjust pin. note 9: shutdown pin current at v shdn = 0v ? ows out of the shutdown pin. note 10: quiescent current in shutdown is equal to the sum total of the shutdown pin current (6a) and the ground pin current (9a). note 11: reverse output current is tested with the input pin grounded. the output pin and the sense pin are forced to the rated output voltage. this current ? ows into the sense pin and out of the ground pin. for the lt1129 (adjustable version) the sense pin is internally tied to the output pin. note 12: the lt1129 regulators are tested and speci? ed under pulse load conditions such that t j ? t a . the lt1129c regulators are 100% tested at t a = 25c. for c-grade devices, regulated output voltage, line regulation and load regulation performance at C40c and 125c is assured by design, characterization and correlation with statistical process controls. the lt1129i regulators are guaranteed over the full C40c to 125c operating junction temperature range. the lt1129mp regulators are 100% tested and guaranteed over the C55c to 125c temperature range. 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 shutdown pin input voltage rating is required for a low impedance source. internal protection devices connected to the shutdown pin will turn on and clamp the pin to approximately 7v or C 0.6v. this range allows the use of 5v logic devices to drive the pin directly. for high impedance sources or logic running on supply voltages greater than 5.5v, the maximum current driven into the shutdown pin must be limited to less than 20ma. note 3: for junction temperatures greater than 110c, a minimum load of 1ma is recommended. for t j > 110c and i out < 1ma, output voltage may increase by 1%. note 4: operating conditions are limited by maximum junction temperature. the regulated output voltage speci? cation will not apply for all possible combinations of input voltage and output current. when operating at maximum input voltage, the output current range must be limited. when operating at maximum output current, the input voltage range must be limited. note 5: the lt1129 is tested and speci? ed with the adjust pin connected to the output pin. note 6: dropout voltage is the minimum input/output voltage required to maintain regulation at the speci? ed output current. in dropout the output guaranteed dropout voltage dropout voltage quiescent current output current (a) dropout voltage (v) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.2 0.4 0.5 112935 g01 0.1 0.3 0.6 0.7 0 = test points t j 125c t j 25c temperature (c) C50 dropout voltage (v) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 50 75 112935 g02 C25 25 100 125 a c d e b a. i load = 700ma b. i load = 500ma c. i load = 300ma d. i load = 100ma e. i load = 10ma temperature (c) C50 quiescent current (a) 70 60 50 40 30 20 10 0 0 50 75 112935 g03 C25 25 100 125 v shdn = 0v v shdn = open (hi) typical performance characteristics
lt1129/lt1129-3.3/lt1129-5 6 112935ff typical performance characteristics lt1129-3.3 quiescent current lt1129-5 quiescent current lt1129 quiescent current lt1129-3.3 output voltage lt1129-5 output voltage lt1129 adjust pin voltage input voltage (v) 0 quiescent current (a) 250 225 200 175 150 125 100 75 50 25 0 8 112935 g06 2 4 6 10 13579 v shdn = 0v i load = 0 r load = v out = v adj v shdn = open (hi) input voltage (v) 0 quiescent current (a) 250 225 200 175 150 125 100 75 50 25 0 8 112935 g05 2 4 6 10 13579 v shdn = 0v i load = 0 r load = v shdn = open (hi) input voltage (v) 0 quiescent current (a) 250 225 200 175 150 125 100 75 50 25 0 8 112935 g04 2 4 6 10 13579 i load = 0 r load = v shdn = 0v v shdn = open (hi) temperature (c) C50 adjust pin voltage (v) 3.400 3.375 3.350 3.325 3.300 3.275 3.250 3.225 3.200 0 50 75 112935 g07 C25 25 100 125 i load = 1ma temperature (c) C50 adjust pin voltage (v) 3.850 3.825 3.800 3.775 3.750 3.725 3.700 3.675 3.650 0 50 75 112935 g09 C25 25 100 125 i load = 1ma temperature (c) C50 output voltage (v) 5.100 5.075 5.050 5.025 5.000 4.975 4.950 4.925 4.900 0 50 75 112935 g08 C25 25 100 125 i load = 1ma lt1129-3.3 ground pin current lt1129-5 ground pin current lt1129 ground pin current input voltage (v) 0 ground pin current (ma) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 8 112935 g12 2 4 6 10 13579 r load = 75 i load = 50ma* r load = 375 i load = 10ma* r load = 38 i load = 100ma* *for v out = 3.75v t j = 25c v out = v adj input voltage (v) 0 ground pin current (ma) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 8 112935 g11 2 4 6 10 13579 r load = 100 i load = 50ma* r load = 500 i load = 10ma* r load = 50 i load = 100ma* *for v out = 5v t j = 25c v out = v sense input voltage (v) 0 ground pin current (ma) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 8 112935 g10 2 4 6 10 13579 r load = 66 i load = 50ma* r load = 330 i load = 10ma* r load = 33 i load = 100ma* t j = 25c v out = v sense *for v out = 3.3v
lt1129/lt1129-3.3/lt1129-5 7 112935ff typical performance characteristics lt1129-3.3 ground pin current lt1129-5 ground pin current lt1129 ground pin current ground pin current shutdown pin threshold (on-to-off) shutdown pin threshold (off-to-on) input voltage (v) 0 ground pin current (ma) 60 50 40 30 20 10 0 8 112935 g14 2 4 6 10 13579 r load = 10 i load = 500ma* r load = 16.6 i load = 300ma* r load = 7.1 i load = 700ma* *for v out = 5v t j = 25c v out = v sense input voltage (v) 0 ground pin current (ma) 60 50 40 30 20 10 0 8 112935 g15 2 4 6 10 13579 r load = 7.5 i load = 500ma* r load = 12.6 i load = 300ma* r load = 5.3 i load = 700ma* *for v out = 3.75v t j = 25c v out = v adj output current (a) 0 ground pin current (ma) 70 60 50 40 30 20 10 0 0.2 0.4 0.5 112935 g16 0.1 0.3 0.6 0.7 t j = 25c t j = 125c t j = C50c v in = 3.3v (lt1129-3.3) v in = 5v (lt1129-5) v in = 3.75v (lt1129) device is operating in dropout temperature (c) C50 shutdown threshold (v) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 50 75 112935 g17 C25 25 100 125 i load = 1ma temperature (c) C50 shutdown threshold (v) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 50 75 112935 g18 C25 25 100 125 i load = 1ma i load = 700ma input voltage (v) 0 ground pin current (ma) 60 50 40 30 20 10 0 8 112935 g13 2 4 6 10 13579 r load = 6.6 i load = 500ma* r load = 11 i load = 300ma* r load = 4.7 i load = 700ma* *for v out = 3.3v t j = 25c v out = v sense shutdown pin current shutdown pin input current adjust pin bias current temperature (c) C50 adjust pin bias current (na) 400 350 300 250 200 150 100 50 0 0 50 75 112935 g21 C25 25 100 125 v adj = v out = 3.75v shutdown pin voltage (v) 0 0 shutdown pin input current (ma) 5 15 20 25 2 4 59 112935 g20 10 13 6 7 8 temperature (c) C50 shutdown pin current (a) 10 9 8 7 6 5 4 3 2 1 0 0 50 75 112935 g19 C25 25 100 125 v shdn = 0v
lt1129/lt1129-3.3/lt1129-5 8 112935ff typical performance characteristics reverse output current current limit current limit reverse output current ripple rejection ripple rejection input voltage (v) 0 short-circuit current (a) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 2 4 5 112935 g23 1 3 6 7 v out = 0v temperature (c) C50 short-circuit current (a) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 50 75 112935 g24 C25 25 100 125 v in = 7v v out = 0v output voltage (v) 0 output current (a) 100 90 80 70 60 50 40 30 20 10 0 8 112935 g25 2 4 6 10 13579 t j = 25c, v in = 0v v out = v sense (lt1129-3.3/lt1129-5) v out = v adj (lt1129) current flows into device lt1129-3.3 lt1129 lt1129-5 temperature (c) C50 ripple rejection (db) 70 68 66 64 62 60 58 56 0 50 75 112935 g26 C25 25 100 125 (v in C v out ) avg = 1v v ripple = 0.5v p-p i l = 0.7a frequency (hz) ripple rejection (db) 100 90 80 70 60 50 40 30 20 10 0 10 1k 10k 1m 112935 g27 100 100k i out = 500ma v in = 6v + 50mv rms ripple c out = 47f solid tantalum c out = 3.3f solid tantalum temperature (c) C50 output current (a) 30 25 20 15 10 5 0 0 50 75 112935 g22 C25 25 100 125 v in = 0v v out = v sense = 5v (lt1129-5) v out = v sense = 3.3v (lt1129-3.3) v out = v adj = 3.75v (lt1129) lt1129-5 transient response load regulation lt1129-5 transient response temperature (c) C50 load regulation (mv) 0 C5 C10 C15 C20 C25 C30 0 50 75 112935 g28 C25 25 100 125 lt1129* lt1129-3.3 lt1129-5 v in = v out (nominal) + 1v i load = 1ma to 700ma *v adj = v out time (s) 0 output voltage deviation (v) 0.10 0.05 0 C0.05 C0.10 400 112935 g29 50 200 300 500 0.6 0.5 load current (a) 100 150 250 350 450 v in = 6v c in = 3.3f c out = 3.3f time (ms) 0 output voltage deviation (v) 0.2 0.1 0 C0.1 C0.2 1.6 112935 g30 0.2 0.8 1.2 2.0 0.7 0.5 0.3 0.1 load current (a) 0.4 0.6 1.0 1.4 1.8 v in = 6v c in = 3.3f c out = 47f
lt1129/lt1129-3.3/lt1129-5 9 112935ff input pin: power is supplied to the device through the input pin. the input pin should be bypassed to ground if the device is more than 6 inches away from the main input ? lter capacitor. in general, the output impedance of a battery rises with frequency so it is advisable to include a bypass capacitor in battery-powered circuits. a bypass capacitor in the range of 1f to 10f is suf? cient. the lt1129 is designed to withstand reverse voltages on the input pin with respect to both ground and the output pin. in the case of a reversed input, which can happen if a battery is plugged in backwards, the lt1129 will act as if there is a diode in series with its input. there will be no reverse current ? ow into the lt1129 and no reverse volt- age will appear at the load. the device will protect both itself and the load. output pin: the output pin supplies power to the load. an output capacitor is required to prevent oscillations. see the applications information section for recommended value of output capacitance and information on reverse output characteristics. shutdown pin ( shdn ): this pin is used to put the device into shutdown. in shutdown the output of the device is turned off. this pin is active low. the device will be shut down if the shutdown pin is actively pulled low. the shutdown pin current with the pin pulled to ground will be 6a. the shutdown pin is internally clamped to 7v and C 0.6v (one v be ). this allows the shutdown pin to be driven directly by 5v logic or by open collector logic with a pull-up resistor. the pull-up resistor is only required to supply the leakage current of the open collector gate, normally several microamperes. pull-up current must be limited to a maximum of 20ma. a curve of shutdown pin input current as a function of voltage appears in the typical performance characteristics. if the shutdown pin is not used it can be left open circuit. the device will be active, output on, if the shutdown pin is not connected. sense pin: for ? xed voltage versions of the lt1129 (lt1129-3.3, lt1129-5) the sense pin is the input to the error ampli? er. optimum regulation will be obtained at the point where the sense pin is connected to the output pin. for most applications the sense pin is connected directly to the output pin at the regulator. in critical applications small voltage drops caused by the resistance (r p ) of pc traces between the regulator and the load, which would normally degrade regulation, may be eliminated by con- necting the sense pin to the output pin at the load as shown in figure 1 (kelvin sense connection). note that the voltage drop across the external pc traces will add to the dropout voltage of the regulator. the sense pin bias current is 15a at the nominal regulated output voltage. this pin is internally clamped to C0.6v (one v be ). adjust pin: for the lt1129 (adjustable version) the adjust pin is the input to the error ampli? er. this pin is internally clamped to 6v and C0.6v (one v be ). this pin has a bias current of 150na which ? ows into the pin. see bias cur- rent curve in the typical performance characteristics. the adjust pin reference voltage is equal to 3.75v referenced to ground. pin functions figure 1. kelvin sense connection the lt1129 is a micropower low dropout regulator with shutdown, capable of supplying 700ma of output current at a dropout voltage of 0.4v. the device operates with very low quiescent current (50a). in shutdown the quiescent current drops to only 16a. in addition to the low quies- cent current the lt1129 incorporates several protection applications information features which make it ideal for use in battery-powered systems. the device is protected against reverse input voltages. in battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the lt1129 acts like it has a diode in series with its output and prevents reverse current ? ow. in lt1129 gnd shdn 112935 f01 sense out r p 1f load 10f r p +
lt1129/lt1129-3.3/lt1129-5 10 112935ff applications information thermal considerations the power handling capability of the device will be limited by the maximum rated junction temperature (125c). the power dissipated by the device will be made up of two components: 1. output current multiplied by the input/output voltage differential: i out ? (v in C v out ), and 2. ground pin current multiplied by the input voltage: i gnd ? v in . the ground pin current can be found by examining the ground pin current curves in the typical performance characteristics. power dissipation will be equal to the sum of the two components listed above. the lt1129 series regulators have internal thermal limiting designed to protect the device during overload conditions. for continuous normal load conditions the maximum junction temperature rating of 125c must not be exceeded. it is important to give careful consideration to all sources of thermal resistance from junction to ambi- ent. additional heat sources mounted nearby must also be considered. for surface mount devices heat sinking is accomplished by using the heat spreading capabilities of the pc board and its copper traces. experiments have shown that the heat spreading copper layer does not need to be electri- cally connected to the tab of the device. the pc material can be very effective at transmitting heat between the pad area, attached to the tab of the device, and a ground or power plane layer either inside or on the opposite side of the board. although the actual thermal resistance of the pc material is high, the length/area ratio of the thermal resistor between layers is small. copper board stiffeners and plated through holes can also be used to spread the heat generated by power devices. the following tables list thermal resistances for each package. for the to-220 package, thermal resistance is given for junction-to-case only since this package is usually mounted to a heat sink. measured values of thermal resistance for several different board sizes and copper areas are listed for each package. all measure- ments were taken in still air on 3/32" fr-4 board with 1-oz in lt1129 gnd shdn 112935 f02 adj out r2 r1 v out = 3.75v 1 + + i adj ? r2 v adj = 3.75v i adj = 150na at 25c output range = 3.75v to 30v r2 r1 () () v out + figure 2. adjustable operation adjustable operation the adjustable version of the lt1129 has an output voltage range of 3.75v to 30v. the output voltage is set by the ratio of two external resistors as shown in figure 2. the device servos the output voltage to maintain the voltage at the adjust pin at 3.75v. the current in r1 is then equal to 3.75v/r1. the current in r2 is equal to the sum of the current in r1 and the adjust pin bias current. the adjust pin bias current, 150na at 25c, ? ows through r2 into the adjust pin. the output voltage can be calculated according to the formula in figure 2. the value of r1 should be less than 400k to minimize errors in the output voltage caused by the adjust pin bias current. note that in shutdown the output is turned off and the divider current will be zero. curves of adjust pin voltage vs temperature and adjust pin bias current vs temperature appear in the typical performance characteristics. the reference voltage at the adjust pin has a positive temperature coef? cient of approximately 15ppm/c. the adjust pin bias current has a negative temperature coef? cient. these effects are small and will tend to cancel each other. the adjustable device is speci? ed with the adjust pin tied to the output pin. this sets the output voltage to 3.75v. speci? cations for output voltages greater than 3.75v will be proportional to the ratio of the desired output voltage to 3.75v (v out /3.75v). for example: load regulation for an output current change of 1ma to 700ma is C 6mv typical at v out = 3.75v. at v out = 12v, load regulation would be: 12v 3.75 v ? C6mv () = C19mv ()
lt1129/lt1129-3.3/lt1129-5 11 112935ff operation copper. this data can be used as a rough guideline in estimating thermal resistance. the thermal resistance for each application will be affected by thermal interactions with other components as well as board size and shape. some experimentation will be necessary to determine the actual value. table 1. q package, 5-lead dd copper area thermal resistance (junction-to-ambient) topside* backside board area 2500 sq. mm 2500 sq. mm 2500 sq. mm 25c/w 1000 sq. mm 2500 sq. mm 2500 sq. mm 27c/w 125 sq. mm 2500 sq. mm 2500 sq. mm 35c/w * tab of device attached to topside copper table 2. st package, 3-lead sot-223 copper area thermal resistance (junction-to-ambient) topside* backside board area 2500 sq. mm 2500 sq. mm 2500 sq. mm 45c/w 1000 sq. mm 2500 sq. mm 2500 sq. mm 45c/w 225 sq. mm 2500 sq. mm 2500 sq. mm 53c/w 100 sq. mm 2500 sq. mm 2500 sq. mm 59c/w * tab of device attached to topside copper table 3. s8 package, 8-lead plastic soic copper area thermal resistance (junction-to-ambient) topside* backside board area 2500 sq. mm 2500 sq. mm 2500 sq. mm 55c/w 1000 sq. mm 2500 sq. mm 2500 sq. mm 55c/w 225 sq. mm 2500 sq. mm 2500 sq. mm 63c/w 100 sq. mm 2500 sq. mm 2500 sq. mm 69c/w * device attached to topside copper t package, 5-lead to-220 thermal resistance (junction-to-case) = 5c/w calculating junction temperature example: given an output voltage of 3.3v, an input voltage range of 4.5v to 5.5v, an output current range of 0ma to 500ma, and a maximum ambient temperature of 50c, what will the maximum junction temperature be? the power dissipated by the device will be equal to: i out max ? (v in max C v out ) + (i gnd ? v in max ) where, i out max = 500ma v in max = 5.5v i gnd at (i out = 500ma, v in = 5.5v) = 25ma so, p = 500ma ? (5.5v C 3.3v) + (25ma ? 5.5v) = 1.24w if we use a dd package, then the thermal resistance will be in the range of 25c/w to 35c/w depending on copper area. so the junction temperature rise above ambient will be approximately equal to: 1.24w ? 30c/w = 37.2c the maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or: t jmax = 50c + 37.2c = 87.2c output capacitance and transient performance the lt1129 is designed to be stable with a wide range of output capacitors. the minimum recommended value is 3.3f with an esr of 2 or less. the lt1129 is a micropower device and output transient response will be a function of output capacitance. see the transient response curves in the typical performance character- istics. larger values of output capacitance will decrease the peak deviations and provide improved output transient response. bypass capacitors, used to decouple individual components powered by the lt1129, will increase the effective value of the output capacitor. protection features the lt1129 incorporates several protection features which make it ideal for use in battery-powered circuits. in addition to the normal protection features associated with monolithic regulators, such as current limiting and thermal limiting, the device is protected against reverse input voltages, and reverse voltages from output to input. for ? xed voltage devices the output and sense pins are tied together at the output.
lt1129/lt1129-3.3/lt1129-5 12 112935ff applications information current limit protection and thermal overload protection are intended to protect the device against current overload conditions at the output of the device. for normal operation, the junction temperature should not exceed 125c. the input of the device will withstand reverse voltages of 30v. current ? ow into the device will be limited to less than 1ma (typically less than 100a) and no negative voltage will appear at the output. the device will protect both itself and the load. this provides protection against batteries that can be plugged in backwards. for ? xed voltage versions of the device, the sense pin is internally clamped to one diode drop below ground. for the adjustable version of the device, the output pin is internally clamped at one diode drop below ground. if the output pin of an adjustable device, or the sense pin of a ? xed voltage device, is pulled below ground, with the input open or grounded, current must be limited to less than 5ma. in circuits where a backup battery is required, several different input /output conditions can occur. the output voltage may be held up while the input is either pulled to ground, pulled to some intermediate voltage, or is left open circuit. current ? ow back into the output will vary depending on the conditions. many battery-powered circuits incorporate some form of power management. the following information will help optimize battery life. table 4 summarizes the following information. the reverse output current will follow the curve in figure 3 when the input pin is pulled to ground. this current ? ows through the output pin to ground. the state of the shutdown pin will have no effect on output current when the input pin is pulled to ground. in some applications it may be necessary to leave the input to the lt1129 unconnected when the output is held high. this can happen when the lt1129 is powered from a recti? ed ac source. if the ac source is removed, then the input of the lt1129 is effectively left ? oating. the reverse output current also follows the curve in figure 3 if the input pin is left open. the state of the shutdown pin will have no effect on the reverse output current when the input pin is ? oating. when the input of the lt1129 is forced to a voltage below its nominal output voltage and its output is held high, the reverse output current will still follow the curve shown in figure 3. this can happen if the input of the lt1129 is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or by a second regulator circuit. when the input pin is forced below the output pin or the output pin is pulled above the input pin, the input current will typically drop to less than 2a (see figure 4). the state of the shutdown pin will have no effect on the reverse output current when the output is pulled above the input. output voltage (v) 0 output pin current (a) 100 90 80 70 60 50 40 30 20 10 0 8 112935 f03 2 4 6 10 13579 t j = 25c v in = 0v v sense = v out current flows into device lt1129-3.3 lt1129 lt1129-5 figure 3. reverse output current input voltage (v) 0 input current (a) 5 4 3 2 1 0 4 112935 f04 1 2 3 5 v out = 3.3v (lt1129-3.3) v out = 5v (lt1129-5) figure 4. input current
lt1129/lt1129-3.3/lt1129-5 13 112935ff 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. applications information f package 20-lead plastic tssop (4.4mm) (ltc dwg # 05-08-1650) obsolete package f20 tssop 0204 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) 134 5 6 7 8910 11 12 14 13 6.40 C 6.60* (.252 C .260) 20 19 18 17 16 15 1.10 (.0433) max 0.05 C 0.15 (.002 C .006) 0.65 (.0256) bsc 6.40 (.252) bsc 0.19 C 0.30 (.0075 C .0118) typ 2 millimeters (inches) dimensions do not include mold flash. mold flash shall not exceed .152mm (.006") per side * note: 1. controlling dimension: millimeters 2. dimensions are in 3. drawing not to scale recommended solder pad layout 0.45 0.05 0.65 bsc 4.50 0.10 6.60 0.10 1.05 0.10 table 4. fault conditions input pin shdn pin output pin < v out (nominal) open (hi) forced to v out (nominal) reverse output current 15a (see figure 3) input current 1a (see figure 4) < v out (nominal) grounded forced to v out (nominal) reverse output current 15a (see figure 3) input current 1a (see figure 4) open open (hi) forced to v out (nominal) reverse output current 15a (see figure 3) open grounded forced to v out (nominal) reverse output current 15a (see figure 3) package description
lt1129/lt1129-3.3/lt1129-5 14 112935ff 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 q(dd5) 0502 .028 C .038 (0.711 C 0.965) typ .143 +.012 C.020 () 3.632 +0.305 C0.508 .067 (1.702) bsc .013 C .023 (0.330 C 0.584) .095 C .115 (2.413 C 2.921) .004 +.008 C.004 () 0.102 +0.203 C0.102 .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 .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 (ltc dwg # 05-08-1461)
lt1129/lt1129-3.3/lt1129-5 15 112935ff 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 st package 3-lead plastic sot-223 (ltc dwg # 05-08-1630) s8 package 8-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) .114 C .124 (2.90 C 3.15) .248 C .264 (6.30 C 6.71) .130 C .146 (3.30 C 3.71) .264 C .287 (6.70 C 7.30) .0905 (2.30) bsc .033 C .041 (0.84 C 1.04) .181 (4.60) bsc .024 C .033 (0.60 C 0.84) .071 (1.80) max 10 max .012 (0.31) min .0008 C .0040 (0.0203 C 0.1016) 10 C 16 .010 C .014 (0.25 C 0.36) 10 C 16 recommended solder pad layout st3 (sot-233) 0502 .129 max .059 max .059 max .181 max .039 max .248 bsc .090 bsc .016 C .050 (0.406 C 1.270) .010 C .020 (0.254 C 0.508) s 45 0C 8 typ .008 C .010 (0.203 C 0.254) so8 0303 .053 C .069 (1.346 C 1.752) .014 C .019 (0.355 C 0.483) typ .004 C .010 (0.101 C 0.254) .050 (1.270) bsc 1 2 3 4 .150 C .157 (3.810 C 3.988) note 3 8 7 6 5 .189 C .197 (4.801 C 5.004) note 3 .228 C .244 (5.791 C 6.197) .245 min .160 .005 recommended solder pad layout .045 .005 .050 bsc .030 .005 typ inches (millimeters) note: 1. dimensions in 2. drawing not to scale 3. these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006" (0.15mm)
lt1129/lt1129-3.3/lt1129-5 16 112935ff 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 1208 rev f ? printed in usa related parts typical application part number description comments lt1121 150ma ldo micropower regulator 30a i q , sot-223 package lt1761 100ma low noise, ldo micropower regulator 20a i q , 20v rms noise lt1762 150ma low noise, ldo micropower regulator 25a i q , 20v rms noise lt1962 300ma low noise, ldo micropower regulator 30a i q , 20v rms noise lt1763 500ma low noise, ldo micropower regulator 30a i q , 20 rms noise lt1963 1.5a low noise, fast transient, ldo regulator 340mv dropout voltage, 40v rms noise lt1764 3a low noise, fast transient, ldo regulator 340mv dropout voltage, 40v rms noise t package 5-lead plastic to-220 (standard) (ltc dwg # 05-08-1421) t5 (to-220) 0801 .028 C .038 (0.711 C 0.965) .067 (1.70) .135 C .165 (3.429 C 4.191) .700 C .728 (17.78 C 18.491) .045 C .055 (1.143 C 1.397) .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 (3.861 C 5.131) .260 C .320 (6.60 C 8.13) .165 C .180 (4.191 C 4.572) .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

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