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lt6654 1 6654fb typical a pplica t ion descrip t ion sot-23 precision wide supply high output drive low noise reference the lt ? 6654 is a family of small precision voltage ref - erences that offers high accuracy, low noise, low drift, low dropout and low power. the lt6654 operates from voltages up to 36v and is fully specifed from C55c to 125c. a buffered output ensures 10ma of output drive with low output impedance and precise load regulation. these features, in combination, make the lt6654 ideal for portable equipment, industrial sensing and control, and automotive applications. the lt6654 was designed with advanced manufactur - ing techniques and curvature compensation to provide 10ppm/c temperature drift and 0.05% initial accuracy. low thermal hysteresis ensures high accuracy and 1.6ppm p-p noise minimizes measurement uncertainty. since the lt6654 can also sink current, it can operate as a low power negative voltage reference with the same precision as a positive reference. the lt6654 is offered in a 6-lead sot-23 package. l , lt, ltc, ltm, 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. basic connection n low drift: a grade: 10ppm/c max b grade: 20ppm/c max n high accuracy: a grade: 0.05% max b grade: 0.10% max n low noise: 1.6ppm p-p (0.1hz to 10hz) n wide supply range to 36v n low thermal hysteresis n line regulation (up to 36v): 5ppm/v max n low dropout voltage: 100mv max n sinks and sources 10ma n load regulation at 10ma: 8ppm/ma max n easily confgured for negative voltage output n fully specifed from C55c to 125c n available output voltage options: 1.25v , 2.048v, 2.5v, 3v, 3.3v, 4.096v, 5v n low profle (1mm) thinsot? package fea t ures a pplica t ions n automotive control and monitoring n high temperature industrial n high resolution data acquisition systems n instrumentation and process control n precision regulators n medical equipment output voltage temperature drift lt6654 c in 0.1f (v out + 0.5v) < v in < 36v 4 6 1 2 c l 1f v out 6654 ta01a temperature (c) ?60 ?0.10 v out accuracy (%) ?0.05 0.05 0.00 0.10 40200?40 ?20 6654 ta01b 140 100 120 60 80 3 typical parts lt6654-2.5
lt6654 2 6654fb p in c on f igura t ion a bsolu t e maxi m u m r a t ings (note 1) 1 2 3 6 5 4 top view s6 package 6-lead plastic tsot-23 v out dnc v in gnd* gnd dnc t jmax = 150c, ja = 192c/w dnc: do not connect *connect pin to device gnd (pin 2) or d er in f or m a t ion input voltage v in to gnd ........................... C0.3v to 38v output voltage v out ......................... C0.3v to v in + 0.3v output short-circuit duration ......................... indefnite specifed t emperature range h-grade ............................................. C40c to 125c mp-grade .......................................... C55c to 125c operating t emperature range................ C55c to 125c storage temperature range (note 2) ..... C 65c to 150c lead temperature (soldering, 10 sec.) (note 9) ................................................................. 300c lead free finish tape and reel (mini) tape and reel part marking* package description specified temperature range lt6654ahs6-1.25#trmpbf lt6654ahs6-1.25#trpbf ltfvd 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-1.25#trmpbf lt6654bhs6-1.25#trpbf ltfvd 6-lead plastic tsot-23 C40c to 125c lt6654amps6-1.25#trmpbf lt6654amps6-1.25#trpbf ltfvd 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-1.25#trmpbf lt6654bmps6-1.25#trpbf ltfvd 6-lead plastic tsot-23 C55c to 125c lt6654ahs6-2.048#trmpbf lt6654ahs6-2.048#trpbf ltfvf 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-2.048#trmpbf lt6654bhs6-2.048#trpbf ltfvf 6-lead plastic tsot-23 C40c to 125c lt6654amps6-2.048#trmpbf lt6654amps6-2.048#trpbf ltfvf 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-2.048#trmpbf lt6654bmps6-2.048#trpbf ltfvf 6-lead plastic tsot-23 C55c to 125c lt6654ahs6-2.5#trmpbf lt6654ahs6-2.5#trpbf ltfjy 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-2.5#trmpbf lt6654bhs6-2.5#trpbf ltfjy 6-lead plastic tsot-23 C40c to 125c lt6654amps6-2.5#trmpbf lt6654amps6-2.5#trpbf ltfjy 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-2.5#trmpbf lt6654bmps6-2.5#trpbf ltfjy 6-lead plastic tsot-23 C55c to 125c lt6654ahs6-3#trmpbf lt6654ahs6-3#trpbf ltfvg 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-3#trmpbf lt6654bhs6-3#trpbf ltfvg 6-lead plastic tsot-23 C40c to 125c lt6654amps6-3#trmpbf lt6654amps6-3#trpbf ltfvg 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-3#trmpbf lt6654bmps6-3#trpbf ltfvg 6-lead plastic tsot-23 C55c to 125c lt6654ahs6-3.3#trmpbf lt6654ahs6-3.3#trpbf ltfvh 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-3.3#trmpbf lt6654bhs6-3.3#trpbf ltfvh 6-lead plastic tsot-23 C40c to 125c lt6654amps6-3.3#trmpbf lt6654amps6-3.3#trpbf ltfvh 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-3.3#trmpbf lt6654bmps6-3.3#trpbf ltfvh 6-lead plastic tsot-23 C55c to 125c lt6654ahs6-4.096#trmpbf lt6654ahs6-4.096#trpbf ltfvj 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-4.096#trmpbf lt6654bhs6-4.096#trpbf ltfvj 6-lead plastic tsot-23 C40c to 125c lt6654amps6-4.096#trmpbf lt6654amps6-4.096#trpbf ltfvj 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-4.096#trmpbf lt6654bmps6-4.096#trpbf ltfvj 6-lead plastic tsot-23 C55c to 125c lt6654ahs6-5#trmpbf lt6654ahs6-5#trpbf ltfvk 6-lead plastic tsot-23 C40c to 125c lt6654bhs6-5#trmpbf lt6654bhs6-5#trpbf ltfvk 6-lead plastic tsot-23 C40c to 125c lt6654amps6-5#trmpbf lt6654amps6-5#trpbf ltfvk 6-lead plastic tsot-23 C55c to 125c lt6654bmps6-5#trmpbf lt6654bmps6-5#trpbf ltfvk 6-lead plastic tsot-23 C55c to 125c trm = 500 pieces. *temperature grades are identifed by a label on the shipping container. consult ltc marketing for parts specifed with wider operating temperature ranges. consult ltc marketing for information on lead based fnish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifcations, go to: http://www.linear.com/tapeandreel/
lt6654 3 6654fb a vailable o p t ions output voltage initial accuracy temperature coefficient order part number** specified temperature range 1.25v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-1.25 lt6654bhs6-1.25 lt6654amps6-1.25 lt6654bmps6-1.25 C40c to 125c C40c to 125c C55c to 125c C55c to 125c 2.048v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-2.048 lt6654bhs6-2.048 lt6654amps6-2.048 lt6654bmps6-2.048 C40c to 125c C40c to 125c C55c to 125c C55c to 125c 2.5v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-2.5 lt6654bhs6-2.5 lt6654amps6-2.5 lt6654bmps6-2.5 C40c to 125c C40c to 125c C55c to 125c C55c to 125c 3v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-3 lt6654bhs6-3 lt6654amps6-3 lt6654bmps6-3 C40c to 125c C40c to 125c C55c to 125c C55c to 125c 3.3v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-3.3 lt6654bhs6-3.3 lt6654amps6-3.3 lt6654bmps6-3.3 C40c to 125c C40c to 125c C55c to 125c C55c to 125c 4.096v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-4.096 lt6654bhs6-4.096 lt6654amps6-4.096 lt6654bmps6-4.096 C40c to 125c C40c to 125c C55c to 125c C55c to 125c 5v 0.05% 0.1% 0.05% 0.1% 10ppm/c 20ppm/c 10ppm/c 20ppm/c lt6654ahs6-5 lt6654bhs6-5 lt6654amps6-5 lt6654bmps6-5 C40c to 125c C40c to 125c C55c to 125c C55c to 125c ** see the order information section for complete part number listing. e lec t rical c harac t eris t ics the l denotes the specifcations which apply over the full operating temperature range, otherwise specifcations are at t a = 25c, c l = 1f and v in = v out + 0.5v, unless otherwise noted. for lt6654-1.25, v in = 2.4v, unless otherwise noted. parameter conditions min typ max units output voltage accuracy lt6654a lt6654b lt6654ah lt6654bh lt6654amp lt6654bmp l l l l C0.05 C0.10 C0.215 C0.43 C0.23 C0.46 0.05 0.10 0.215 0.43 0.23 0.46 % % % % % % output voltage temperature coeffcient (note 3) lt6654a lt6654b l l 3 10 10 20 ppm/c ppm/c line regulation v out + 0.5v v in 36v lt6654-2.048, lt6654-2.5, lt6654-3, lt6654-3.3, lt6654-4.096, lt6654-5 l 1.2 5 10 ppm/v ppm/v 2.4v v in 36v lt6654-1.25 l 1.2 5 10 ppm/v ppm/v load regulation (note 4) i out(source) = 10ma lt6654-2.048, lt6654-2.5, lt6654-3, lt6654-3.3, lt6654-4.096, lt6654-5 lt6654-1.25 l l 3 6 8 15 15 20 ppm/ma ppm/ma ppm/ma ppm/ma
lt6654 4 6654fb 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: if the parts are stored outside of the specifed temperature range, the output may shift due to hysteresis. note 3: temperature coeffcient is measured by dividing the maximum change in output voltage by the specifed temperature range. note 4: load regulation is measured on a pulse basis from no load to the specifed load current. output changes due to die temperature change must be taken into account separately. note 5: excludes load regulation errors. note 6: peak-to-peak noise is measured with a 1-pole highpass flter at 0.1hz and 2-pole lowpass flter at 10hz. the unit is enclosed in a still-air environment to eliminate thermocouple effects on the leads. the test time is 10 seconds. rms noise is measured on a spectrum analyzer in a shielded environment where the intrinsic noise of the instrument is removed to determine the actual noise of the device. note 7: long-term stability typically has a logarithmic characteristic and therefore, changes after 1000 hours tend to be much smaller than before that time. total drift in the second thousand hours is normally less than one third that of the frst thousand hours with a continuing trend toward reduced drift with time. long-term stability will also be affected by differential stresses between the ic and the board material created during board assembly. note 8: hysteresis in output voltage is created by package stress that differs depending on whether the ic was previously at a higher or lower temperature. output voltage is always measured at 25c, but the ic is cycled to the hot or cold temperature limit before successive measurements. hysteresis measures the maximum output change for the averages of three hot or cold temperature cycles. for instruments that are stored at well controlled temperatures (within 20 or 30 degrees of operational temperature), its usually not a dominant error source. note 9: the stated temperature is typical for soldering of the leads during manual rework. for detailed ir refow recommendations, refer to the applications information section. e lec t rical c harac t eris t ics the l denotes the specifcations which apply over the full operating temperature range, otherwise specifcations are at t a = 25c, c l = 1f and v in = v out + 0.5v, unless otherwise noted. for lt6654-1.25, v in = 2.4v, unless otherwise noted. parameter conditions min typ max units load regulation (note 4) i out(sink) = 10ma lt6654-2.048, lt6654-2.5, lt6654-3, lt6654-3.3, lt6654-4.096, lt6654-5 lt6654-1.25 l l 9 15 20 30 25 30 ppm/ma ppm/ma ppm/ma ppm/ma dropout voltage (note 5) v in C v out , ?v out = 0.1% i out = 0ma lt6654-2.048, l t6654-2.5, lt6654-3, lt6654-3.3, l t6654-4.096, lt6654-5 i out(source) = 10ma i out(sink) = C10ma l l l 55 100 120 450 50 mv mv mv mv minimum input voltage lt6654-1.25, ?v out = 0.1%, i out = 0ma lt6654-1.25, ?v out = 0.1%, i out = 10ma l l 1.5 1.6 1.8 2.4 v v v supply current no load l 350 600 a a output short-circuit current short v out to gnd short v out to v in 40 30 ma ma output voltage noise (note 6) 0.1hz f 10hz lt6654-1.25 lt6654-2.048 lt6654-2.5 lt6654-3 lt6654-3.3 lt6654-4.096 lt6654-5 10hz f 1khz 0.8 1.0 1.5 1.6 1.7 2.0 2.2 2.0 ppm p-p ppm p-p ppm p-p ppm p-p ppm p-p ppm p-p ppm p-p ppm rms turn-on time 0.1% settling, c load = 1f 150 s long-term drift of output voltage (note 7) 60 ppm/khr hysteresis (note 8) ?t = 0c to 70c ?t = C40c to 85c ?t = C40c to 125c ?t = C55c to 125c 30 40 90 100 ppm ppm ppm ppm
lt6654 5 6654fb typical p er f or m ance c harac t eris t ics 1.25v load regulation (sourcing) 1.25v load regulation (sinking) 1.25v output noise 0.1hz to 10hz 1.25v minimum input voltage (sourcing) 1.25v minimum input voltage (sinking) 1.2v output voltage noise spectrum 1.25v output voltage temperature drift 1.25v turn-on characteristics 1.25v output impedance vs frequency temperature (c) ?60 1.2485 1.2490 1.2495 reference voltage (v) 1.2500 1.2505 1.2510 1.2515 1.2520 ?40 ?20 0 6654 g01 20 40 60 80 140 100 120 three typical parts output current (ma) 0.1 ?50 ?40 output voltage change (ppm) ?30 ?20 ?10 0 30 20 10 1 6654 g04 10 ?40c 25c 125c ?55c output current (ma) 0.1 0 output voltage change (ppm) 40 80 20 60 100 140 160 180 120 200 1 6654 g05 10 125c ?40c ?55c 25c output noise (1v/div) time (1s/div) 6654 g06 109876543210 minimum input voltage (v) 1 1.2 1.4 1.6 1.8 2 2.2 0.1 output current (ma) 1 10 6654 g07 2.4 25c ?40c ?55c 125c minimum input voltage (v) 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 0.1 output current (ma) 1 10 6654 g08 1.8 ?40c ?55c 125c 25c frequency (khz) 0.01 0.1 1 10 0 50 100 150 250 300 350 noise voltage (nv hz) 200 400 6654 g09 100 i o = 5ma i o = 0a th e characteristic curves are similar across the lt6654 family. curves from the lt6654-1.25, lt6654-2.5 and the lt6654-5 represent the full range of typical performance of all voltage options. characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 20s/div gnd gnd v in 1v/div v out 0.5v/div 6654 g02 c load = 1f frequency (khz) 0.1 0.01 output impedance () 0.1 10 1 100 1 10 100 6654 g03 1000 c l = 1f c l = 10f
lt6654 6 6654fb typical p er f or m ance c harac t eris t ics 2.5v load regulation (sourcing) 2.5v load regulation (sinking) 2.5v output noise 0.1hz to 10hz 2.5v minimum v in to v out differential (sourcing) 2.5v minimum v in to v out differential (sinking) 2.5v output voltage noise spectrum 2.5v output voltage temperature drift 2.5v supply current vs input voltage 2.5v line regulation temperature (c) ?60 ?20 20 60 140 100 2.498 2.499 2.500 2.501 output voltage (v) 2.502 6654 g10 three typical parts input voltage (v) 0 5 10 15 20 25 30 35 0 input current (a) 300 600 500 400 100 200 6654 g11 40 ?55c 125c ?40c 25c input voltage (v) 0 5 10 15 20 25 30 35 2.4950 2.4960 output voltage (v) 2.5000 2.5050 2.5030 2.5010 2.5040 2.5020 2.4970 2.4980 2.4990 6654 g12 40 ?40c ?55c 25c 125c output current (ma) 0.1 1 ?40 ?30 ?20 ?10 output voltage change (ppm) 0 10 6654 g13 10 ?55c 25c 125c ?40c output current (ma) 0.1 1 0 100 120 140 output voltage change (ppm) 160 20 40 60 80 180 6654 g14 10 125c ?55c ?40c 25c time (1s/div) output noise (1v/div) 6654 g15 input-output voltage (mv) 0 200 300 0.1 1 output current (ma) 10 6654 g16 400 15010050 250 350 25c ?55c ?40c 125c input-output voltage (mv) ?300 ?100 0 0.1 1 output current (ma) 10 6654 g17 100 ?150?200?250 ?50 50 ?40c 25c ?55c 125c frequency (khz) 0.01 0.1 1 10 0 50 100 150 250 300 350 noise voltage (nv hz) 200 400 6654 g18 100 i o = 5ma i o = 0a th e characteristic curves are similar across the lt6654 family. curves from the lt6654-1.25, lt6654-2.5 and the lt6654-5 represent the full range of typical performance of all voltage options. characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
lt6654 7 6654fb typical p er f or m ance c harac t eris t ics 2.5v turn-on characteristics 2.5v line transient response 2.5v load transient response (sourcing) 2.5v hysteresis plot for C40c and 125c 2.5v long term drift 2.5v load transient response (sinking) 2.5v integrated noise 10hz to 10khz 2.5v power supply rejection ratio vs frequency 2.5v output impedance vs frequency frequency (khz) 0.01 0.1 1 0.1 1 10 integrated noise (v rms ) 100 6654 g19 10 frequency (khz) 0.1 1 10 100 ?100 ?90 ?80 ?70 ?50 ?40 ?30 power supply rejection ratio (db) ?60 ?20 6654 g20 1000 c l = 1f c l = 10f frequency (khz) 1 10 100 0.1 1 10 output impedance () 100 6654 g21 1000 c l = 10f c l = 1f 20s/div gnd gnd v in 1v/div v out 1v/div 6654 g22 c load = 1f 50s/div v in 0.5v/div 3v/dc v out 2mv/div/ac 2.5v/dc 6654 g23 c load = 1f 50s/div i out 0ma v out 20mv/div/ac 2.5v/dc 6654 g24 c load = 1f 5ma distribution (ppm) ? 150 0 number of units 4 8 12 16 20 24 28 32 36 40 44 48 ?1 00 ? 125 ?50?75 6654 g25 ?25 0 25 1 00 1 25 1 50 50 75 max avg hot cycle 25c to 125c to 25c max avg cold cycle 25c to ?40c to 25c time (hours) 0 400 800 1600 1200 ?150 ?120 ?90 ?60 0 ?30 120 output voltage change (ppm) 150 60 30 90 6654 g26 2000 t a = 35c 50s/div 0ma v out 20mv/div/ac 2.5v/dc 6654 g27 c load = 1f i out 5ma th e characteristic curves are similar across the lt6654 family. curves from the lt6654-1.25, lt6654-2.5 and the lt6654-5 represent the full range of typical performance of all voltage options. characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
lt6654 8 6654fb typical p er f or m ance c harac t eris t ics 5v load regulation (sourcing) 5v load regulation (sinking) 5v output noise 0.1hz to 10hz 5v minimum v in to v out differential (sourcing) 5v minimum v in to v out differential (sinking) 5v output voltage noise spectrum 5v output voltage temperature drift 5v turn-on characteristics 5v output impedance vs frequency temperature (c) ?60 0 80604020 ?40 ?20 120100 4.993 4.994 4.995 4.996 4.998 4.997 5.002 reference voltage (v) 5.003 5.000 4.999 5.001 6654 g28 140 three typical parts 50s/div gnd gnd v out 2v/div v in 2v/div 6654 g29 c load = 1f output current (ma) 0.1 1 ?20 10 0 output voltage change (ppm) 50 40 30 20 6654 g31 10 ?10 125c ?40c 25c ?55c output current (ma) 0.1 1 0 60 40 output voltage change (ppm) 220 120 100 80 140 200 180 160 6654 g32 10 20 ?55c 25c ?40c 125c output noise (4v/div) time (1s/div) 6654 g33 109876543210 input-output voltage (mv) 0 50 100 150 200 250 300 350 0.1 output current (ma) 1 10 6654 g34 400 125c ?40c ?55c 25c input-output voltage (mv) ?300 ?250 ?200 ?150 ?100 ?50 0 50 0.1 output current (ma) 1 10 6654 g35 100 25c ?55c ?40c 125c frequency (khz) 0.01 0.1 1 10 0 50 100 150 250 300 350 noise voltage (nv hz) 200 450 500 550 400 600 6654 g36 100 i o = 5ma i o = 0a frequency (khz) 0.1 1 10 100 0.01 0.1 1 10 output impedance () 100 6654 g30 1000 c l = 10f c l = 1f th e characteristic curves are similar across the lt6654 family. curves from the lt6654-1.25, lt6654-2.5 and the lt6654-5 represent the full range of typical performance of all voltage options. characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
lt6654 9 6654fb b lock diagra m p in func t ions gnd (pin 1): internal function. this pin must be tied to ground, near pin 2. gnd (pin 2): primary device ground. dnc (pin 3): do not connect. keep leakage current from this pin to v in or gnd to a minimum. v in (pin 4): power supply. bypass v in with a 0.1f capacitor to ground. dnc (pin 5): do not connect. keep leakage current from this pin to v in or gnd to a minimum. v out (pin 6): output voltage. an output capacitor of 1f minimum is required for stable operation. ? + v out 6 4 6654 bd bandgap v in 3 5 dnc dnc gnd gnd 2 1
lt6654 10 6654fb bypass and load capacitors the lt6654 voltage references should have an input by - pass capacitor of 0.1f or larger, however the bypassing on other components nearby is suffcient. in high voltage applications, v in > 30v, an output short-circuit to ground can create an input voltage transient that could exceed the maximum input voltage rating. to prevent this worst-case condition, an rc input line flter of 10s (i.e. 10? and 1f) is recommended. these references also require an output capacitor for stability. the optimum output capacitance for most applications is 1f, although larger values work as well. this capacitor affects the turn-on and settling time for the output to reach its fnal value. a pplica t ions i n f or m a t ion figure 1 shows the turn-on time for the lt6654-2.5 with a 0.1f input bypass and 1f load capacitor. figure 2 shows the output response to a 0.5v transient on v in with the same capacitors. the test circuit of figure 3 is used to measure the stability with various load currents. with r l = 1k, the 1v step pro - duces a current step of 1ma. figure 4 shows the response to a 0.5ma load. figure 5 is the output response to a sourcing step from 4ma to 5ma, and figure 6 is th e output response of a sinking step from 4ma to 5ma. figure 1. turn-on characteristics of lt6654-2.5 lt6654-2.5 c in 0.1f v in 3v 4 6 1, 2 c l 1f v gen 1k 6654 f03 1v figure 2. output response to 0.5v ripple on v in figure 3. load current response time test circuit 20s/div gnd gnd v in 1v/div v out 1v/div 6654 f01 c load = 1f 50s/div v in 0.5v/div 3v/dc v out 2mv/div/ac 2.5v/dc 6654 f02 c load = 1f
lt6654 11 6654fb figure 4. lt6654-2.5 sourcing and sinking 0.5ma figure 5. lt6654-2.5 sourcing 4ma to 5ma figure 6. lt6654-2.5 sinking 4ma to 5ma 50s/div i out ?0.5ma v out 20mv/div/ac 2.5v/dc 6654 f04 c load = 1f 0.5ma a pplica t ions i n f or m a t ion 50s/div i out 4ma v out 10mv/div/ac 2.5v/dc 6654 f05 c load = 1f 5ma 50s/div i out ?5ma v out 10mv/div/ac 2.5v/dc 6654 f06 c load = 1f ?4ma positive or negative operation in addition to the series connection, as shown on the front page of this data sheet, the lt6654 can be operated as a negative voltage reference. the circuit in figure 7 shows an lt6654 confgured for negative operation. in this confguration, a positive volt - age is required at v in (pin 4) to bias the lt6654 internal circuitry. this voltage must be current limited with r1 to keep the output pnp transistor from turning on and driv - ing the grounded output. c1 provides stability during load transients. this connection maintains the same accuracy and temperature coeffcient of the positive connected lt6654. figure 7. using the lt6654-2.5 to build a C2.5v reference lt6654-2.5 6 4 1, 2 v ee v out = ?2.5v 0.1f 3v r1 4.7k 6654 f07 c1 1f v ee ? v out 550a + i out r
lt6654 12 6654fb a pplica t ions i n f or m a t ion similar to a real world application. the boards were then placed into a constant temperature oven with t a = 35c, their outputs scanned regularly and measured with an 8.5 digit dvm. long-term drift curves are shown in figure 8. their drift is much smaller after the frst thousand hours. long-term drift long-term drift cannot be extrapolated from accelerated high temperature testing. this erroneous technique gives drift numbers that are wildly optimistic. the only way long-term drift can be determined is to measure it over the time interval of interest. the lt6654 drift data was taken on 40 parts that were soldered into pc boards figure 8. lt6654-2.5 long term drift time (hours) 0 200 400 800 600 ?80 ?40 0 output voltage change (ppm) 80 40 6654 f08a 1000 long term drift: first thousand hours time (hours) 1000 1200 1400 1800 1600 ?80 ?40 0 output voltage change (ppm) 80 40 6654 f08b 2000 long term drift: second thousand hours (normalized to the first thousand hours)
lt6654 13 6654fb figure 11. thermal hysteresis C40c to 125c distribution (ppm) ? 150 0 number of units 10 20 30 40 50 ?1 00 ?50 6654 f11 0 1 00 1 50 50 max avg hot cycle 25c to 125c to 25c max avg cold cycle 25c to ?40c to 25c a pplica t ions i n f or m a t ion figure 9. maximum allowed power dissipation of the lt6654 figure 10. typical power dissipation of the lt6654 temperature (c) 0 0 power (w) 0.1 0.2 0.6 0.5 0.4 0.3 0.7 20 40 60 80 6654 f09 100 120 140 t = 150c ja = 192c/w 130mw v in (v) 0 0 power (w) 0.05 0.25 0.20 0.15 0.10 0.40 0.35 0.30 5 10 15 6654 f10 20 25 30 35 40 10ma load no load 335mw power dissipation the power dissipation in the lt6654 is dependent on v in , load current and the package. the lt6654 package has a thermal resistance, or e ja , of 192c/w. a curve that illustrates allowed power dissipation versus temperature for the 6-lead sot-23 package is shown in figure 9. the power dissipation of the lt6654-2.5 as a function of input voltage is shown in figure 10. the top curve shows power dissipation with a 10ma load and the bottom curve shows power dissipation with no load. when operated within its specifed limits of v in = 36v and sourcing 10ma, the lt6654-2.5 consumes about 335mw at room temperature. the power-derating curve in figure 9 shows the lt6654- 2.5 can only safely dissipate 130mw at 125c, which is less than its maximum power output. care must be taken when designing the circuit so that the maximum junction temperature is not exceeded. for best performance, junc - tion temperature should be kept below 125c. the lt6654 includes output current limit circuitry, as well as thermal limit circuitry, to protect the reference from damage in the event of excessive power dissipation. the lt6654 is protected from damage by a thermal shutdown circuit. however, changes in performance may occur as a result of operation at high temperature. hysteresis the hysteresis data is shown in figure 11. the lt6654 is capable of dissipating relatively high power. for example, with a 36v input voltage and 10ma load current applied to the lt6654-2.5, the power dissipation is p d = 33.5v ? 10ma = 335mw, which causes an increase in the die temperature of 64c. this could increase the junction temperature above 125c (t jmax is 150c) and may cause the output to shift due to thermal hysteresis.
lt6654 14 6654fb a pplica t ions i n f or m a t ion pc board layout the mechanical stress of soldering a surface mount volt - age reference to a pc board can cause the output voltage to shift and temperature coeffcient to change. these two changes are not correlated. for example, the voltage may shift but the temperature coeffcient may not. to reduce the effects of stress-related shifts, mount the reference near the short edge of the pc board or in a corner. in addition, slots can be cut into the board on two sides of the device. the capacitors should be mounted close to the lt6654. the gnd and v out traces should be as short as possible to minimize i ? r drops, since high trace resistance directly impacts load regulation. figure 12. lead free refow profle minutes temperature (c) 0 0 75 ramp down t p 30s 40s t l 130s 120s 150 225 300 2 4 6 8 6654 f12 10 ramp to 150c 380s t p = 260c t l = 217c t s(max) = 200c t s = 190c t = 150c figure 13. output voltage shift due to ir refow (%) change in output (ppm) ?140 0 number of units 2 4 6 8 10 12 14 ?120 ?100 ?80 ?60 6654 f13 ?40 0 ?20 260c 3 cycles 260c 1 cycle ir refow shift the different expansion and contraction rates of the ma - terials that make up the lt6654 package may cause the output voltage to shift after undergoing ir refow. lead free solder refow profles reach over 250c, considerably more than with lead based solder. a typical lead free ir refow profle is shown in figure 12. similar profles are found using a convection refow oven. lt6654 devices run up to three times through this refow process show that the standard deviation of the output voltage increases with a slight negative mean shift of 0.003% as shown in figure 13. while there can be up to 0.014% of output voltage shift, the overall drift of the lt6654 after ir refow does not vary signifcantly.
lt6654 15 6654fb lt6654-2.5 2n2905 220 in out 4.7f 6654 ta03 1f i out up to 300ma 4.5v < v in < 36v boosted output current reference extended supply range reference boosted output current with current limit 1 2 led1* * led cannot be ommitted the led clamps the voltage drop across the 220 and limits output current 6654 ta04 220 4.7f 1f i out up to 100ma 10 2n2905 4.5v < v in < 36v lt6654-2.5 in out octal dac reference typical a pplica t ions lt6654-2.5 bzx84c12 330k up to 160v mmbt5551 6654 ta02 1f 0.1f 2.65v < v in < 5v 6654 ta05 0.1f 10f v ref v cc cs dac e dac a dac b dac c dac d dac f dac g gnd dac h ltc2600 sck sdi clear v in 0.1f lt6654-2.5 in out
lt6654 16 6654fb p ackage descrip t ion s6 package 6-lead plastic tsot-23 (reference ltc dwg # 05-08-1636) 1.50 ? 1.75 (note 4) 2.80 bsc 0.30 ? 0.45 6 plcs (note 3) datum ?a? 0.09 ? 0.20 (note 3) s6 tsot-23 0302 rev b 2.90 bsc (note 4) 0.95 bsc 1.90 bsc 0.80 ? 0.90 1.00 max 0.01 ? 0.10 0.20 bsc 0.30 ? 0.50 ref pin one id note: 1. dimensions are in millimeters 2. drawing not to scale 3. dimensions are inclusive of plating 4. dimensions are exclusive of mold flash and metal burr 5. mold flash shall not exceed 0.254mm 6. jedec package reference is mo-193 3.85 max 0.62 max 0.95 ref recommended solder pad layout per ipc calculator 1.4 min 2.62 ref 1.22 ref
lt6654 17 6654fb 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. r evision h is t ory rev date description page number a 12/10 added voltage options (1.250v, 2.048v, 3.000v, 4.096v, 5.000v) refected throughout the data sheet. 1-18 b 3/11 revised conditions for output voltage noise in the electrical characteristics section. 4
lt6654 18 6654fb linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com linear technology corporation 2010 lt 0311 rev b ? printed in usa r ela t e d p ar t s typical a pplica t ion part number description comments LT1460 micropower series reference 0.075% max, 10ppm/c max drift, 2.5v, 5v and 10v versions, msop, pdip, s0-8, sot-23 and to-92 packages lt1461 micropower precision ldo series reference 3ppm/c max drift, 0c to 70c, C40c to 85c, C40c to 125c options in so-8 lt1790 micropower precision series references 0.05% max, 10ppm/c max, 60a supply, sot-23 package lt6650 micropower reference with buffer amplifer 0.05% max, 5.6a supply, sot-23 package ltc6652 precision low drift low noise buffered reference 0.5% max, 5ppm/c max, 2.1ppm p-p noise (0.1hz to 10hz) 100% tested at C40c, 25c and 125c lt6660 tiny micropower series reference 0.2% max, 20ppm/c max, 20ma output current, 2mm = 2mm dfn ltc6655 precision low noise reference 2ppm/c max, 650nv p-p noise (0.1hz to 10hz) 100% tested at C40c, 25c and 125c lt6656 800na precision voltage reference 800na, 10ppm/c max, 0.05% max, sot-23 package 16-bit adc reference 6654 ta06 sdo sdi f o gnd sck cs in+ in? + ? v cc v ref 4.6v < v s < 36v lt6654-4.096 ltc2480 to mcu ?2.048v < v differential < 2.048v in out 0.1f 10f

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