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LT6654 1 6654f typical application description sot-23 precision wide supply high output drive voltage reference the lt ? 6654 is a small precision voltage reference that offers high accuracy, low noise, low drift, low dropout and low power. the LT6654 operates from voltages up to 36v and is fully speci? ed from C40c 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. 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 con? gured for negative voltage output n fully speci? ed from C40c to 125c n available output voltage: 2.5v for 1.25v, 2.048v, 3v, 3.3v, 4.096v, 5v versions, consult ltc marketing n low pro? le (1mm) thinsot? package features applications 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 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. output voltage temperature drift lt 6 6 5 4 c in 0.1f (v out + 0.1v) < v in < 36v 46 12 c l 1f v out 6654 ta01a temperature (c) C50 C0.100 v out accuracy (%) C0.050 0.050 0.000 0.100 40 10 C20 6654 ta01b 130 100 70 3 typical parts
LT6654 2 6654f pin configuration absolute maximum ratings (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) order information lead free finish tape and reel part marking* package description specified temperature range LT6654ahs6-2.5#pbf LT6654ahs6-2.5#trpbf ltfjy 6-lead plastic tsot-23 C40c to 125c LT6654bhs6-2.5#pbf LT6654bhs6-2.5#trpbf ltfjy 6-lead plastic tsot-23 C40c to 125c consult ltc marketing for parts speci? ed with wider operating temperature ranges. *the performance grade is identi? ed by a label on the shipping container. consult ltc marketing for information on non-standard lead based ? nish parts. 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/ available options output voltage initial accuracy temperature coefficient part number 2.5v 0.05% 0.1% 10ppm/c 20ppm/c LT6654ahs6-2.5 LT6654bhs6-2.5 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 .......................... inde? nite operating temperature range................ C40c to 125c storage temperature range (note 2) ..... C65c to 150c lead temperature (soldering, 10 sec.) (note 9) ................................................................. 300c electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c, c l = 1f and v in = v out + 0.5v, unless otherwise noted. parameter conditions min typ max units output voltage accuracy LT6654a LT6654b C0.05 C0.10 0.05 0.10 % % output voltage temperature coef? cient (note 3) LT6654a LT6654b l l 3 6 10 20 ppm/c ppm/c line regulation v out + 0.5v v in 36v l 1.2 5 10 ppm/v ppm/v
LT6654 3 6654f electrical characteristics note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: if the parts are stored outside of the speci? ed temperature range, the output may shift due to hysteresis. note 3: temperature coef? cient is measured by dividing the maximum change in output voltage by the speci? ed temperature range. note 4: load regulation is measured on a pulse basis from no load to the speci? ed 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 3-pole highpass at 0.1hz and 4-pole lowpass ? lter 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. the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c, c l = 1f and v in = v out + 0.5v, unless otherwise noted. load regulation (note 4) i out(source) = 10ma l 38 15 ppm/ma ppm/ma i out(sink) = 10ma l 920 30 ppm/ma ppm/ma minimum operating voltage (note 5) v in C v out , v out = 0.1% i out = 0ma i out(source) = 10ma i out(sink) = C10ma l l l 55 100 120 450 50 mv mv mv mv supply current no load l 350 550 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 10hz f 1khz 1.6 1.8 ppm p-p ppm rms turn-on time 0.1% settling, c load = 1f 120 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 30 40 90 ppm ppm ppm 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 ? rst 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 re? ow recommendations, refer to the applications information section.
LT6654 4 6654f load regulation (sourcing) load regulation (sinking) output noise 0.1hz to 10hz minimum v in C v out differential (sourcing) minimum v in C v out differential (sinking) output voltage noise spectrum output voltage temperature drift supply current vs input voltage line regulation typical performance characteristics temperature (c) C70 2.498 output voltage (v) 2.499 2.500 2.501 2.502 C50 C30 C10 10 6654 g01 30 50 70 90 150 110 130 three typical parts input voltage (v) 0 0 input current (a) 100 200 300 400 500 600 5101520 6654 g02 25 30 35 40 125c C40c 25c input voltage (v) 0 2.4980 output voltage (v) 2.4985 2.4990 2.4995 2.5000 2.5015 2.5010 2.5005 2.5020 5101520 6654 g03 25 30 35 40 125c C40c 25c output current (ma) 0.1 C40 output voltage change (ppm) C30 C20 C10 0 10 1.0 6654 g04 10.0 C40c 125c 25c output current (ma) 0.1 0 output voltage change (ppm) 40 80 20 60 100 140 160 120 180 1.0 6654 g05 10.0 C40c 125c 25c time (1s/div) output noise (1v/div) 6654 g06 input-output voltage (v) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.1 output current (ma) 1.0 10.0 6654 g07 0.4 0.35 C40c 125c 25c input-output voltage (mv) C250 C200 C150 C100 C50 0 0.1 output current (ma) 1.0 10.0 6654 g08 50 C40c 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 = 0a i o = 5ma
LT6654 5 6654f typical performance characteristics turn-on characteristics line transient response load transient response (sourcing) 2.5v hysteresis plot for C40c and 125c 2.5v long term drift load transient response (sinking) integrated noise 10hz to 10khz power supply rejection ratio vs frequency output impedance vs frequency frequency (khz) 0.01 0.1 1 10 0.1 1 10 integrated noise (v rms ) 100 6654 g10 frequency (khz) 0.1 1 10 C100 C90 C80 C70 C50 C40 C30 power supply rejection ratio (db) C60 C20 6654 g11 100 1000 c l = 1f c l = 10f frequency (khz) 1 10 100 1000 0.1 1 10 output impedance () 100 6654 g12 c l = 1f c l = 10f distribution (ppm) C150 0 number of units 4 8 12 16 20 24 28 32 36 40 44 48 C125 C100 C75 C50 6654 g16 C25 0 2 5 100 125 50 75 max avg hot cycle 25c to 125c to 25c max avg cold cycle 25c to C40c to 25c time (20s/div) v out v in 2.5v 3v 1v 0v 6654 g13 time (50s/div) ac- coupled v in 2.5v 2mv div 3.5v 3v 6654 g14 time (50s/div) c l = 1f ac- coupled i out v out 2.5v 20mv div 0ma 5ma 6654 g15 time (50s/div) c l = 1f ac- coupled i out 20mv div v out 2.5v 5ma 0ma 6654 g18 time (hours) 0 C100 output voltage change (ppm) C80 C60 C40 C20 0 20 40 60 80 100 100 200 300 400 6654 g17 500 600 700 1000 800 900 t a = 35c
LT6654 6 6654f block diagram pin functions gnd (pin 1): internal function. this pin must be tied to ground. 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. C + v out 6 4 6654 bd bandgap v in 3 5 dnc dnc gnd gnd 2 1
LT6654 7 6654f 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 may be suf? cient. 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 capaci- tor affects the turn-on and settling time for the output to reach its ? nal value. applications information 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 the 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 46 1, 2 c l 1f v gen 1k 6654 f03 1v figure 4. LT6654-2.5 sourcing and sinking 0.5ma figure 2. output response to 0.5v ripple on v in figure 5. LT6654-2.5 sourcing 4ma to 5ma figure 3. response time test circuit figure 6. LT6654-2.5 sinking 4ma to 5ma time (20s/div) v out v in 2.5v 3v 6654 f01 time (50s/div) ac- coupled v in 2.5v 3.5v 3v 6654 f02 C0.5ma 2.5v sinking 0.5ma sourcing 6654 f04 2.5v 4ma 5ma 6654 f05 2.5v C4ma C5ma 6654 f06
LT6654 8 6654f positive or negative operation the LT6654 can be operated in series mode or as a negative voltage reference. a typical series connection is shown on the front page of this data sheet. the circuit in figure 7 shows an LT6654 con? gured for negative operation. in this con? guration, 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 driving the grounded output. c1 provides stability dur- ing load transients. this connection maintains nearly the same accuracy and temperature coef? cient of the positive connected LT6654. applications information dissipation is approximately 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. 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 coef? cient to change. these two changes are not correlated. for example, the voltage may shift but the temperature coef? cient 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. high trace resistance directly impacts load regulation. ir re? ow 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 re? ow. lead free solder re? ow pro? les reach over 250c, considerably more than with lead based solder. a typical lead free ir re? ow pro? le is shown in figure 8. similar pro? les are found using a convection re? ow oven. LT6654 devices run up 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 similar to a real world application. the boards were then placed into a constant temperature oven with t a = 30c, their outputs scanned regularly and measured with an 8.5 digit dvm. long-term drift curves are shown in the typical performance characteristics section. hysteresis the hysteresis data is shown in the typical performance characteristics. the LT6654 is capable of dissipating relatively high power. with a maximum input voltage and 10ma load current applied to the LT6654-2.5 the power LT6654-2.5 6 4 1, 2 v ee v out = C2. 5 0.1f 3v 4.7k 6654 f c1 1f v ee C v out 500a r1 = figure 7. using the LT6654-2.5 to build a C2.5v reference figure 8. lead free re? ow pro? le minutes temperature (c) 0 0 75 ramp down t p 30s 40s t l 130s 120s 150 225 300 2468 6654 f08 10 ramp to 150c 380s t p = 260c t l = 217c t s(max) = 200c t s = 190c t = 150c
LT6654 9 6654f applications information to three times through this re? ow process show that the standard deviation of the output voltage increases with a s l i gh t n e g a t i v e m e a n s h i f t o f 0.0 0 3% a s s h ow n i n f i gur e 9. while there can be up to 0.014% of output voltage shift, the overall drift of the LT6654 after ir re? ow does not vary signi? cantly. 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 ja , of 230c/w. a curve that illustrates allowed power dissipation versus temperature for the 6-lead sot-23 package is shown in figure 10. the power dissipation of the LT6654-2.5 as a function of input voltage is shown in figure 11. the top curve shows power dissipation with a 10ma load and the bottom curve shows power dissipation with no load. when operated within its speci? ed limits of v in = 36v and sourcing 10ma, the LT6654-2.5 consumes about 335mw at room temperature. the power-derating curve in figure 10 shows the LT6654-2.5 can only safely dissipate 108mw 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. 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. figure 9. output voltage shift due to ir re? ow (%) figure 10. maximum allowed dissipation for LT6654 figure 11. 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 f10 100 120 140 t = 150c ja = 230c/w 108mw v in (v) 0 0 power (w) 0.05 0.25 0.20 0.15 0.10 0.40 0.35 0.30 51015 6654 f11 20 25 30 35 40 10ma load no load 335mw change in output (ppm) C140 0 number of units 2 4 6 8 10 12 14 C120 C100 C80 C60 6654 f09 C40 0 C20 260c 3 cycles 260c 1 cycle
LT6654 10 6654f typical applications LT6654-2.5 bzx84c12 330k up to 160v mmbt5551 6654 ta02 c3 1f 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 limit s ou tp u t cu rrent LT6654-2.5 in out 6654 ta04 220 4.7f 1f i out up to 100ma 10 2n2905 4.5v < v in < 36v LT6654-2.5 2.65v < v in < 5v in out 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 octal dac reference
LT6654 11 6654f information furnished by linear technology corpor ation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- t i o n t h a t t h e i n t e r c o n n e c t i o n o f i t s c i r c u i t s a s d e s c r i b e d h e r e i n w i l l n o t i n f r i n g e o n e x i s t i n g p a t e n t r i g h t s . package description 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 ? 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 12 6654f 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 0710 ? printed in usa related parts typical application 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 ampli? er 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 12-bit adc reference 6654 ta06 sdo ref ref comp gnd sck cs ch0 in + ch1 in + v cc 4.75v < v cc < 5.25v LT6654-2.5 ltc2301 in out 0.1f 22f 10f 0.1f

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