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ultralow noise, ldo xfet ? voltage references with curr ent sink and source adr440/adr441/adr443/adr444/adr445 rev. a information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 www.analog.com fax: 781.461.3113 ?2006 analog devices, inc. all rights reserved. features ultralow noise (0.1 hz to 10 hz) adr440: 1 v p-p adr441: 1.2 v p-p adr443: 1.4 v p-p adr444: 1.8 v p-p adr445: 2.25 v p-p superb temperature coefficient a grade: 10 ppm/c b grade: 3 ppm/c low dropout operation: 500 mv input range: (v out + 500 mv) to 18 v high output source and sink current: +10 ma and ?5 ma wide temperature range: ?40c to +125c applications precision data acquisition systems high resolution data converters battery-powered instrumentations portable medical instruments industrial process control systems precision instruments optical control circuits pin configurations notes 1. nc = no connect 2. tp = test pin (do not connect) tp 1 v in 2 nc 3 gnd 4 tp 8 nc 7 v out 6 trim 5 adr440/ adr441/ adr443/ adr444/ adr445 top view (not to scale) 05428-001 figure 1. 8-lead soic_n (r-suffix) 05428-002 tp 1 v in 2 nc 3 gnd 4 tp 8 nc 7 v out 6 trim 5 adr440/ adr441/ adr443/ adr444/ adr445 top view (not to scale) notes 1. nc = no connect 2. tp = test pin (do not connect) figure 2. 8-lead msop (rm-suffix) general description the adr44x series is a family of xfet voltage references featuring ultralow noise, high accuracy, and low temperature drift performance. using analog devices, inc., patented temperature drift curvature correction and xfet (extra implanted junction fet) technology, voltage change vs. temperature nonlinearity in the adr44x is greatly minimized. the xfet references offer better noise performance than buried zener references, and xfet references operate off low supply voltage headroom (0.5 v). this combination of features makes the adr44x family ideally suited for precision signal conversion applications in high-end data acquisition systems, optical networks, and medical applications. the adr44x family has the capability to source up to 10 ma of output current and sink up to 5 ma. it also comes with a trim terminal to adjust the output voltage over a 0.5% range without compromising performance. offered in two electrical grades, the adr44x family is avail- able in 8-lead msop and narrow soic packages. all versions are specified over the extended industrial temperature range of ?40c to +125c. table 1. selection guide model output voltage (v) initial accuracy, (mv) temperature coefficient (ppm/c) adr440a 2.048 3 10 adr440b 2.048 1 3 adr441a 2.500 3 10 adr441b 2.500 1 3 adr443a 3.000 4 10 adr443b 3.000 1.2 3 adr444a 4.096 5 10 adr444b 4.096 1.6 3 adr445a 5.000 6 10 adr445b 5.000 2 3
adr440/adr441/adr443/adr444/adr445 rev. a | page 2 of 20 table of contents features .............................................................................................. 1 applications....................................................................................... 1 pin configurations ........................................................................... 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications..................................................................................... 3 adr440 electrical ch aracteristics............................................. 3 adr441 electrical ch aracteristics............................................. 4 adr443 electrical ch aracteristics............................................. 5 adr444 electrical ch aracteristics............................................. 6 adr445 electrical ch aracteristics............................................. 7 absolute maximum ratings............................................................ 8 thermal resistance ...................................................................... 8 esd caution.................................................................................. 8 typical performance characteristics ............................................. 9 theory of operation ...................................................................... 14 power dissipation considerations........................................... 14 basic voltage reference connections ..................................... 14 noise performance ..................................................................... 14 turn-on time ............................................................................ 14 applications..................................................................................... 15 output adjustment .................................................................... 15 bipolar outputs .......................................................................... 15 negative reference ..................................................................... 15 programmable voltage source ................................................. 16 programmable current source ................................................ 16 high voltage floating current source .................................... 16 precision output regulator (boosted reference).................. 17 outline dimensions ....................................................................... 18 ordering guide .......................................................................... 19 revision history 9/06rev. 0 to rev. a updated format..................................................................universal changes to features.......................................................................... 1 changes to pin configurations....................................................... 1 changes to the specifications section ........................................... 3 changes to figure 4 and figure 5................................................... 9 inserted figure 6 and figure 7 ........................................................ 9 changes to figure 15...................................................................... 11 changes to the power dissipation considerations section...... 14 changes to figure 35 and figure 36............................................. 15 changes to figure 38 and table 9................................................. 16 updated outline dimensions ....................................................... 18 changes to ordering guide .......................................................... 19 10/05revision 0: initial version
adr440/adr441/adr443/adr444/adr445 rev. a | page 3 of 20 specifications adr440 electrical characteristics v in = 3 v to 18 v, t a = 25c, c in = c out = 0.1 f, unless otherwise noted. table 2. parameter symbol conditions min typ max unit output voltage v o a grade 2.045 2.048 2.051 v b grade 2.047 2.048 2.049 v initial accuracy v oerr a grade 3 mv 0.15 % b grade 1 mv 0.05 % temperature drift tcv o a grade ?40c < t a < +125c 2 10 ppm/c b grade ?40c < t a < +125c 1 3 ppm/c line regulation v o /v in ?40c < t a < +125c ?20 +10 +20 ppm/v load regulation v o /i load i load = 0 ma to 10 ma, v in = 3.5 v, ?40c < t a < +125c ?50 +50 ppm/ma v o /i load i load = 0 ma to ?5 ma, v in = 3.5 v, ?40c < t a < +125c ?50 +50 ppm/ma quiescent current i in no load, ?40c < t a < +125c 3 3.75 ma voltage noise e n p-p 0.1 hz to 10 hz 1 v p-p voltage noise density e n 1 khz 45 nv/hz turn-on settling time t r 10 s long-term stability 1 v o 1000 hours 50 ppm output voltage hysteresis v o_hys 70 ppm ripple rejection ratio rrr f in = 10 khz ?75 db short circuit to gnd i sc 27 ma supply voltage operating range v in 3 18 v supply voltage headroom v in ? v o 500 mv 1 the long-term stability specif ication is noncumulative. the drift in the subseque nt 1000-hour period is si gnificantly lower th an in the first 1000-hour period.
adr440/adr441/adr443/adr444/adr445 rev. a | page 4 of 20 adr441 electrical characteristics v in = 3 v to 18 v, t a = 25c, c in = c out = 0.1 f, unless otherwise noted. table 3. parameter symbol conditions min typ max unit output voltage v o a grade 2.497 2.500 2.503 v b grade 2.499 2.500 2.501 v initial accuracy v oerr a grade 3 mv 0.12 % b grade 1 mv 0.04 % temperature drift tcv o a grade ?40c < t a < +125c 2 10 ppm/c b grade ?40c < t a < +125c 1 3 ppm/c line regulation v o /v in ?40c < t a < +125c 10 20 ppm/v load regulation v o /i load i load = 0 ma to 10 ma, v in = 4 v, ?40c < t a < +125c ?50 +50 ppm/ma v o /i load i load = 0 ma to ?5 ma, v in = 4 v, ?40c < t a < +125c ?50 +50 ppm/ma quiescent current i in no load, ?40c < t a < +125c 3 3.75 ma voltage noise e n p-p 0.1 hz to 10 hz 1.2 v p-p voltage noise density e n 1 khz 48 nv/hz turn-on settling time t r 10 s long-term stability 1 v o 1000 hours 50 ppm output voltage hysteresis v o_hys 70 ppm ripple rejection ratio rrr f in = 10 khz ?75 db short circuit to gnd i sc 27 ma supply voltage operating range v in 3 18 v supply voltage headroom v in ? v o 500 mv 1 the long-term stability specif ication is noncumulative. the drift in subsequent 1000-hour period is significantly lower than i n the first 1000-hour period.
adr440/adr441/adr443/adr444/adr445 rev. a | page 5 of 20 adr443 electrical characteristics v in = 3.5 v to 18 v, t a = 25c, c in = c out = 0.1 f, unless otherwise noted. table 4. parameter symbol conditions min typ max unit output voltage v o a grade 2.996 3.000 3.004 v b grade 2.9988 3.000 3.0012 v initial accuracy v oerr a grade 4 mv 0.13 % b grade 1.2 mv 0.04 % temperature drift tcv o a grade ?40c < t a < +125c 2 10 ppm/c b grade ?40c < t a < +125c 1 3 ppm/c line regulation v o /v in ?40c < t a < +125c 10 20 ppm/v load regulation v o /i load i load = 0 ma to 10 ma, v in = 5 v, ?40c < t a < +125c ?50 +50 ppm/ma v o /i load i load = 0 ma to ?5 ma, v in = 5 v, ?40c < t a < +125c ?50 +50 ppm/ma quiescent current i in no load, ?40c < t a < +125c 3 3.75 ma voltage noise e n p-p 0.1 hz to 10 hz 1.4 v p-p voltage noise density e n 1 khz 57.6 nv/hz turn-on settling time t r 10 s long-term stability 1 v o 1000 hours 50 ppm output voltage hysteresis v o_hys 70 ppm ripple rejection ratio rrr f in = 10 khz ?75 db short circuit to gnd i sc 27 ma supply voltage operating range v in 3.5 18 v supply voltage headroom v in ? v o 500 mv 1 the long-term stability specif ication is noncumulative. the drift in the subseque nt 1000-hour period is si gnificantly lower th an in the first 1000-hour period.
adr440/adr441/adr443/adr444/adr445 rev. a | page 6 of 20 adr444 electrical characteristics v in = 4.6 v to 18 v, t a = 25c, c in = c out = 0.1 f, unless otherwise noted. table 5. parameter symbol conditions min typ max unit output voltage v o a grade 4.091 4.096 4.101 v b grade 4.0944 4.096 4.0976 v initial accuracy v oerr a grade 5 mv 0.13 % b grade 1.6 mv 0.04 % temperature drift tcv o a grade ?40c < t a < +125c 2 10 ppm/c b grade ?40c < t a < +125c 1 3 ppm/c line regulation v o /v in ?40c < t a < +125c 10 20 ppm/v load regulation v o /i load i load = 0 ma to 10 ma, v in = 5.5 v, ?40c < t a < +125c ?50 +50 ppm/ma v o /i load i load = 0 ma to ?5 ma, v in = 5.5 v, ?40c < t a < +125c ?50 +50 ppm/ma quiescent current i in no load, ?40c < t a < +125c 3 3.75 ma voltage noise e n p-p 0.1 hz to 10 hz 1.8 v p-p voltage noise density e n 1 khz 78.6 nv/hz turn-on settling time t r 10 s long-term stability 1 v o 1000 hours 50 ppm output voltage hysteresis v o_hys 70 ppm ripple rejection ratio rrr f in = 10 khz ?75 db short circuit to gnd i sc 27 ma supply voltage operating range v in 4.6 18 v supply voltage headroom v in ? v o 500 mv 1 the long-term stability specif ication is noncumulative. the drift in the subseque nt 1000-hour period is si gnificantly lower th an in the first 1000-hour period.
adr440/adr441/adr443/adr444/adr445 rev. a | page 7 of 20 adr445 electrical characteristics v in = 5.5 v to 18 v, t a = 25c, c in = c out = 0.1 f, unless otherwise noted. table 6. parameter symbol conditions min typ max unit output voltage v o a grade 4.994 5.000 5.006 v b grade 4.998 5.000 5.002 v initial accuracy v oerr a grade 6 mv 0.12 % b grade 2 mv 0.04 % temperature drift tcv o a grade ?40c < t a < +125c 2 10 ppm/c b grade ?40c < t a < +125c 1 3 ppm/c line regulation v o /v in ?40c < t a < +125c 10 20 ppm/v load regulation v o /i load i load = 0 ma to 10 ma, v in = 6.5 v, ?40c < t a < +125c ?50 +50 ppm/ma v o /i load i load = 0 ma to ?5 ma, v in = 6.5 v, ?40c < t a < +125c ?50 +50 ppm/ma quiescent current i in no load, ?40c < t a < +125c 3 3.75 ma voltage noise e n p-p 0.1 hz to 10 hz 2.25 v p-p voltage noise density e n 1 khz 90 nv/hz turn-on settling time t r 10 s long-term stability 1 v o 1000 hours 50 ppm output voltage hysteresis v o_hys 70 ppm ripple rejection ratio rrr f in = 10 khz C75 db short circuit to gnd i sc 27 ma supply voltage operating range v in 5.5 18 v supply voltage headroom v in ? v o 500 mv 1 the long-term stability specif ication is noncumulative. the drift in the subseque nt 1000-hour period is si gnificantly lower th an in the first 1000-hour period.
adr440/adr441/adr443/adr444/adr445 rev. a | page 8 of 20 absolute maximum ratings t a = 25c, unless otherwise noted. table 7. parameter rating supply voltage 20 v output short-circuit duration to gnd indefinite storage temperature range ?65c to +125c operating temperature range ?40c to +125c junction temperature range ?65c to +150c lead temperature, soldering (60 sec) 300c stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. thermal resistance ja is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. table 8. thermal resistance package type ja jc unit 8-lead soic_n (r-suffix) 130 43 c/w 8-lead msop (rm-suffix) 190 c/w esd caution
adr440/adr441/adr443/adr444/adr445 rev. a | page 9 of 20 typical performance characteristics v in = 7 v, t a = 25c, c in = c out = 0.1 f, unless otherwise noted. temperature (c) output voltage (v) 2.5020 2.5015 2.5005 2.5010 2.5000 2.4995 2.4990 ?40 5?10?25 50 35 20 110958065 125 05428-003 figure 3. adr441 output voltage vs. temperature temperature (c) output voltage (v) 3.0020 3.0015 3.0000 3.0005 3.0010 2.9995 2.9985 2.9990 2.9980 ?40 5 ?10 ?25 50 3520 110 958065 125 unit 1 unit 2 unit 3 05428-004 figure 4. adr443 output voltage vs. temperature temperature (c) output voltage (v) 4.0980 4.0975 4.0960 4.0965 4.0970 4.0955 4.0945 4.0950 4.0940 ?40 5 ?10 ?25 50 3520 110 958065 125 05428-005 unit 1 unit 2 unit 3 figure 5. adr444 output voltage vs. temperature 2.051 2.050 2.049 2.048 2.047 2.046 2.045 ?40 ?20 0 20 100 806040 120 temperature (c) output voltage (v) 05428-042 figure 6. adr440 output voltage vs. temperature 5.006 5.004 5.002 5.000 4.998 4.996 4.994 ?40 ?20 0 20 100 806040 120 temperature (c) output voltage (v) 05428-043 figure 7. adr445 output voltage vs. temperature input voltage (v) supply current (ma) 4.0 3.5 3.0 2.5 2.0 46 10 81 14 12 18 05428-006 6 +125c ?40c +25c figure 8. adr441 supply current vs. input voltage
adr440/adr441/adr443/adr444/adr445 rev. a | page 10 of 20 temperature ( c) supply current (ma) 4.0 3.5 3.0 2.5 2.0 ?40 5?10 ?25 50 3520 110958065 125 05428-007 figure 9. adr441 supply current vs. temperature input voltage (v) supply current (ma) 3.5 3.4 3.2 3.3 3.0 2.9 2.8 2.7 2.6 3.1 2.5 5.3 9.3 7.3 13.3 11.3 17.3 15.3 19.3 05428-008 ?40 c +125 c +25 c figure 10. adr445 supply current vs. input voltage temperature (c) quiescent current (ma) 3.25 3.15 3.05 2.95 2.85 2.75 ?40 5?10?25 50 35 20 110958065 125 05428-009 figure 11. adr445 quiescent current vs. temperature temperature (c) line regul a tion (ppm/v) 10 8 6 2 4 0 ?40 5?10?25 50 35 20 110958065 125 05428-010 figure 12. adr441 line regulation vs. temperature temperature (c) load regul a tion (ppm/ma) 60 55 50 40 35 45 30 ?40 5?10?25 50 35 20 110958065 125 05428-011 v in = 18v i load = 0ma to 10ma v in = 6v figure 13. adr441 load regulation vs. temperature temperature (c) line regul a tioin (ppm/v) 7 6 5 4 1 2 3 0 ?40 5?10?25 50 35 20 110958065 125 05428-012 figure 14. adr445 line regulation vs. temperature
adr440/adr441/adr443/adr444/adr445 rev. a | page 11 of 20 temperature (c) load regul a tion (ppm/ma) 50 40 30 20 ?30 ?40 ?20 ?10 0 10 ?50 ?40 5?10?25 50 35 20 110958065 125 05428-013 i load = 0ma to +10ma i load = 0ma to ?5ma v in = 6v figure 15. adr445 load regulation vs. temperature load current (ma) differenti a l voltage (v) 0.7 0.6 0.5 0.3 0.2 0.1 0.4 0 ?10 ?5 0 5 10 05428-014 +125c ?40c +25c figure 16. adr441 minimum input/output differential voltage vs. load current temperature (c) minimum headroom (v) 0.5 0.4 0.3 0.2 0.1 0 ?40 5?10?25 50 35 20 110958065 125 05428-015 no load figure 17. adr441 minimum headroom vs. temperature load current (ma) differenti a l voltage (v) 1.0 0.9 0.8 0.7 0.6 0.5 0.3 0.2 0.1 0.4 0 ?5 0 5 10 05428-016 +125c ?40c +25c figure 18. adr445 minimum input/output differential voltage vs. load current temperature (c) minimum headroom (v) 0.5 0.4 0.3 0.2 0.1 0 ?40 5?10?25 50 35 20 110958065 125 05428-017 no load figure 19. adr445 minimum headroom vs. temperature 05428-018 v out = 1v/div v in = 5v/div c in , c out = 0.1f time = 10s/div figure 20. adr441 turn-on response
adr440/adr441/adr443/adr444/adr445 rev. a | page 12 of 20 05428-019 v out = 1v/div v in = 5v/div c in , c out = 0.1f time = 200s/div figure 21. adr441 turn-off response 05428-020 v out = 1v/div v in = 5v/div c in = 0.1f c out = 10f time = 200s/div figure 22. adr441 turn-on response 05428-021 2v/div 4v 2mv/div c in = 0.1f c out = 10f time = 100s/div figure 23. adr441 line transient response 05428-022 load off load on 5mv/div c in , c out = 0.1f time = 200s/div figure 24. adr441 load transient response 05428-023 load off load on 5mv/div c in = 0.1f c out = 10f time = 200s/div figure 25. adr441 load transient response 05428-024 ch1 p-p 1.18v 1v/div time = 1s/div figure 26. adr441 0.1 hz to 10.0 hz voltage noise
adr440/adr441/adr443/adr444/adr445 rev. a | page 13 of 20 05428-025 50v/div time = 1s/div ch1 p-p 49v figure 27. adr441 10 hz to 10 khz voltage noise 05428-026 ch1 p-p 2.24v 1v/div time = 1s/div figure 28. adr445 0.1 hz to 10.0 hz voltage noise 05428-027 50v/div time = 1s/div ch1 p-p 66v figure 29. adr445 10 hz to 10 khz voltage noise deviation (ppm) number of parts 16 0 05428-028 14 12 10 8 6 4 2 ?130 ?150 ?110 ?90 ?70 ?50 ?10 ?30 10 30 50 70 110 90 130 150 figure 30. adr441 typical output voltage hysteresis frequency (hz) output impedance ( ? ) 100k 10k 1k 100 10 05428-029 adr445 adr443 adr441 10 9 8 7 5 6 4 3 2 1 0 figure 31. output im pedance vs. frequency frequency (hz) ripple rejection r a tio (db) 100k 1m 10k 1k 100 05428-030 ?10 0 ?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100 figure 32. ripple rejection ratio vs. frequency
adr440/adr441/adr443/adr444/adr445 rev. a | page 14 of 20 theory of operation the adr44x series of references uses a new reference generation technique known as xfet (extra implanted junction fet). this technique yields a reference with low dropout, good thermal hysteresis, and exceptionally low noise. the core of the xfet reference consists of two junction field-effect transistors (jfets), one of which has an extra channel implant to raise its pinch-off voltage. by running the two jfets at the same drain current, the difference in pinch-off voltage can be amplified and used to form a highly stable voltage reference. the intrinsic reference voltage is around 0.5 v with a negative temperature coefficient of about C120 ppm/c. this slope is essentially constant to the dielectric constant of silicon, and it can be closely compensated for by adding a correction term generated in the same fashion as the proportional-to-temperature (ptat) term used to compensate band gap references. the advantage of an xfet reference is its correction term, which is approx- imately 20 times lower and requires less correction than that of a band gap reference. because most of the noise of a band gap reference comes from the temperature compensation circuitry, the xfet results in much lower noise. figure 33 shows the basic topology of the adr44x series. the temperature correction term is provided by a current source with a value designed to be proportional to absolute temperature. the general equation is ( ) ptat p out ir1vgv ?= (1) where: g is the gain of the reciprocal of the divider ratio. v p is the difference in pinch-off voltage between the two jfets. i ptat is the positive temperature coefficient correction current. adr44x devices are created by on-chip adjustment of r2 and r3 to achieve the different voltage option at the reference output. i ptat i 1 * i 1 *extra channel implant v out = g ( ? v p ? r1 i ptat ) r2 v in v out gnd r3 r1 ? v p 05428-033 adr44x figure 33. simplified schematic device por dissipation considrations the adr44x family of references is guaranteed to deliver load currents to 10 ma with an input voltage that ranges from 3 v to 18 v. when these devices are used in applications at higher currents, users should use the following equation to account for the temperature effects of increases in power dissipation: aja dj tpt + = (2) where: t j and t a are the junction and ambient temperatures, respectively. p d is the device power dissipation. ja is the device package thermal resistance. basic votage reference connections the adr44x family requires a 0.1 f capacitor on the input and the output for stability. while not required for operation, a 10 f capacitor at the input can help with line voltage transient performance. no tes 1. nc = no connect 2. tp = test pin (do not connect) 05428-034 6 v out 0.1f + v in 10f 0.1f tp 1 nc 3 4 tp 8 nc 7 trim 5 adr440/ adr441/ adr443/ adr444/ adr445 top view (not to scale) 2 gnd figure 34. basic voltage reference configuration nois prformanc the noise generated by the adr44x family of references is typically less than 1.4 v p-p over the 0.1 hz to 10.0 hz band for adr440, adr441, and adr443. figure 26 shows the 0.1 hz to 10 hz noise of the adr441, which is only 1.2 v p-p. the noise measurement is made with a band-pass filter made of a 2-pole high-pass filter with a corner frequency at 0.1 hz and a 2-pole low-pass filter with a corner frequency at 10.0 hz. turn-on time upon application of power (cold start), the time required for the output voltage to reach its final value within a specified error band is defined as the turn-on settling time . two compo- nents normally associated with this are the time for the active circuits to settle and the time for the thermal gradients on the chip to stabilize. figure 20 and figure 21 show the turn-on and turn-off settling times for the adr441.
adr440/adr441/adr443/adr444/adr445 rev. a | page 15 of 20 applications output adjustment the adr44x family features a trim pin that allows the user to adjust the output voltage of the part over a limited range. this allows errors from the reference and overall system errors to be trimmed out by connecting a potentiometer between the output and the ground, with the wiper connected to the trim pin. figure 35 shows the optimal trim configuration. r1 allows fine adjustment of the output and is not always required. r p should be sufficiently large so that the maximum output current from the adr44x is not exceeded. trim v in v o = 0.5% 0.1f 0.1f gnd r2 1k? r p 10k? 05428-035 v out 6 2 5 4 r1 100k ? adr440/ adr441/ adr443/ adr444/ adr445 figure 35. adr44x trim function using the trim function has a negligible effect on the temperature performance of the adr44x. however, all resistors need to be low temperature coefficient resistors, or errors can occur. bipolar outputs by connecting the output of the adr44x to the inverting terminal of an operational amplifier, it is possible to obtain both positive and negative reference voltages. care must be taken when choosing resistor r1 and resistor r2 (see figure 36 ). they must be matched as closely as possible to ensure minimal differences between the negative and positive outputs. in addition, care must be taken to ensure performance over temperature. use low temperature coefficient resistors if the circuit is used over temperature; otherwise, differences exist between the two outputs. adr440/ adr441/ adr443/ adr444/ adr445 6 2 4 v in v out gnd r1 10k ? r2 10k ? r3 5k? ?10v +10v ?5v +5v 0.1f 0.1f 05428-036 + v dd figure 36. adr44x bipolar outputs negative reference figure 37 shows how to connect the adr44x and a standard operational amplifier, such as the op1177, to provide negative voltage. this configuration provides two main advantages. first, it only requires two devices; therefore, it does not require excessive board space. second, and more importantly, it does not require any external resistors. this means the performance of this circuit does not rely on choosing low temperature coefficient resistors to ensure accuracy. adr440/ adr441/ adr443/ adr444/ adr445 + v dd ?v ref gnd v in v out ?v dd 05428-037 2 6 4 figure 37. adr44x negative reference v out is at virtual ground, and the negative reference is taken directly from the output of the operational amplifier. if the negative supply voltage is close to the reference output, the operational amplifier must be dual supply and have low offset and rail-to-rail capability.
adr440/adr441/adr443/adr444/adr445 rev. a | page 16 of 20 programmable voltage source to obtain different voltages than those offered by the adr44x, some extra components are needed. in figure 38, two potentiometers are used to set the desired voltage, while the buffering amplifier provides current drive. the potentiometer connected between v out and gnd, with its wiper connected to the noninverting input of the operational amplifier, takes care of coarse trim. the second potentiometer, with its wiper connected to the trim terminal of the adr44x, is used for fine adjustment. resolution depends on the end-to-end resistance value and the resolution of the selected potentiometer. adr440/ adr441/ adr443/ adr444/ adr445 6 2 4 v in v out gnd r2 10k ? adj v ref 05428-038 + v dd r1 10k ? figure 38. programmable voltage source for a completely programmable solution, replace the two potentiometers in figure 38 with one analog devices dual digital potentiometer, offered with either an spi? or an i 2 c? interface. these interfaces set the position of the wiper on both potentiometers and allow the output voltage to be set. table 9 lists compatible analog devices digital potentiometers. table 9. digital potentiometer parts part no. no. of channels no. of positions itf r (k) v dd 1 ad5251 2.00 64.00 i 2 c 1, 10, 50, 100 5.5 ad5207 2.00 256.00 spi 10, 50, 100 5.5 ad5242 2.00 256.00 i 2 c 10, 100, 1m 5.5 ad5262 2.00 256.00 spi 20, 50, 200 15 ad5282 2.00 256.00 i 2 c 20, 50, 100 15 ad5252 2.00 256.00 i 2 c 1, 10, 50, 100 5.5 ad5232 2.00 256.00 spi 10, 50, 100 5.5 ad5235 2.00 1024.00 spi 25, 250 5.5 adn2850 2.00 1024.00 spi 25, 250 5.5 1 can also use a negative supply. adding a negative supply to the operational amplifier allows the user also to produce a negative programmable reference, by connecting the reference output to the inverting terminal of the operational amplifier. choose feedback resistors to minimize errors over temperature. programmable current source it is possible to build a programmable current source using a setup similar to the programmable voltage source, as shown in figure 39. the constant voltage on the gate of the transistor sets the current through the load. varying the voltage on the gate changes the current. this circuit does not require a dual digital potentiometer. adr440/ adr441/ adr443/ adr444/ adr445 v in v out gnd i load v cc r sense ad5259 2 6 4 0.1f 0.1f 05428-039 figure 39. programmable current source high voltage floating current source use the circuit in figure 40 to generate a floating current source with minimal self heating. this particular configuration can operate on high supply voltages, determined by the breakdown voltage of the n-channel jfet. adr440/ adr441/ adr443/ adr444/ adr445 v in v out gnd op90 + v s sst111 vishay 2n3904 ?v s 05428-040 2 6 4 figure 40. floating current source
adr440/adr441/adr443/adr444/adr445 rev. a | page 17 of 20 precision output regulator (boosted reference) adr440/ adr441/ adr443/ adr444/ adr445 6 2 v in v out r l 200? c l 1f 2n7002 ?v 15v v o c in 0.1f c out 0.1f v in gnd 4 05428-041 figure 41. boosted output reference higher current drive capability can be obtained, without sacrificing accuracy, by using the circuit in figure 41 . the operational amplifier regulates the mosfet turn-on, forcing v o to equal the v ref . current is then drawn from v in , allowing increased current drive capability. the circuit allows a 50 ma load; if higher current drive is required, use a larger mosfet. for fast transient response, add a buffer at v o to aid with capacitive loading.
adr440/adr441/adr443/adr444/adr445 rev. a | page 18 of 20 outline dimensions 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 0.50 (0.0196) 0.25 (0.0099) 45 8 0 1.75 (0.0688) 1.35 (0.0532) seating plane 0.25 (0.0098) 0.10 (0.0040) 4 1 85 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2440) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarity 0.10 controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012-aa figure 42. 8-lead standard small outline package [soic_n] narrow body (r-8) dimensions shown in millimeters and (inches) 0.80 0.60 0.40 8 0 4 8 1 5 4.90 bsc pin 1 0.65 bsc 3.00 bsc seating plane 0.15 0.00 0.38 0.22 1.10 max 3.00 bsc coplanarity 0.10 0.23 0.08 compliant to jedec standards mo-187-aa figure 43. 8-lead mini small outline package [msop] (rm-8) dimensions show in millimeters
adr440/adr441/adr443/adr444/adr445 rev. a | page 19 of 20 ordering guide initial accuracy, model output voltage (v) (mv) (%) temperature coefficient package (ppm/c) package description branding temperature range package option adr440arz 1 2.048 3 0.15 10 8-lead soic_n C40c to +125c r-8 adr440arz-reel7 1 2.048 3 0.15 10 8-lead soic_n C40c to +125c r-8 adr440armz 1 2.048 3 0.15 10 8-lead msop r01 C40c to +125c rm-8 adr440armz-reel7 1 2.048 3 0.15 10 8-lead msop r01 C40c to +125c rm-8 adr440brz 1 2.048 1 0.05 3 8-lead soic_n C40c to +125c r-8 adr440brz-reel7 1 2.048 1 0.05 3 8-lead soic_n C40c to +125c r-8 adr441arz 1 2.500 3 0.12 10 8-lead soic_n C40c to +125c r-8 adr441arz-reel7 1 2.500 3 0.12 10 8-lead soic_n C40c to +125c r-8 adr441armz 1 2.500 3 0.12 10 8-lead msop r02 C40c to +125c rm-8 adr441armz-reel7 1 2.500 3 0.12 10 8-lead msop r02 C40c to +125c rm-8 adr441brz 1 2.500 1 0.04 3 8-lead soic_n C40c to +125c r-8 adr441brz-reel7 1 2.500 1 0.04 3 8-lead soic_n C40c to +125c r-8 adr443arz 1 3.000 4 0.13 10 8-lead soic_n C40c to +125c r-8 adr443arz-reel7 1 3.000 4 0.13 10 8-lead soic_n C40c to +125c r-8 adr443armz 1 3.000 4 0.13 10 8-lead msop r03 C40c to +125c rm-8 adr443armz-reel7 1 3.000 4 0.13 10 8-lead msop r03 C40c to +125c rm-8 adr443brz 1 3.000 1.2 0.04 3 8-lead soic_n C40c to +125c r-8 adr443brz-reel7 1 3.000 1.2 0.04 3 8-lead soic_n C40c to +125c r-8 adr444arz 1 4.096 5 0.13 10 8-lead soic_n C40c to +125c r-8 adr444arz-reel7 1 4.096 5 0.13 10 8-lead soic_n C40c to +125c r-8 adr444armz 1 4.096 5 0.13 10 8-lead msop r04 C40c to +125c rm-8 adr444armz-reel7 1 4.096 5 0.13 10 8-lead msop r04 C40c to +125c rm-8 adr444brz 1 4.096 1.6 0.04 3 8-lead soic_n C40c to +125c r-8 adr444brz-reel7 1 4.096 1.6 0.04 3 8-lead soic_n C40c to +125c r-8 adr445arz 1 5.000 6 0.12 10 8-lead soic_n C40c to +125c r-8 adr445arz-reel7 1 5.000 6 0.12 10 8-lead soic_n C40c to +125c r-8 adr445armz 1 5.000 6 0.12 10 8-lead msop r05 C40c to +125c rm-8 ADR445ARMZ-REEL7 1 5.000 6 0.12 10 8-lead msop r05 C40c to +125c rm-8 adr445brz 1 5.000 2 0.04 3 8-lead soic_n C40c to +125c r-8 adr445brz-reel7 1 5.000 2 0.04 3 8-lead soic_n C40c to +125c r-8 1 z = pb-free part.
adr440/adr441/adr443/adr444/adr445 rev. a | page 20 of 20 ?2006 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d05428-0-9/06(a) notes purchase of licensed i 2 c components of analog devices or one of its sublicensed associated companies conveys a license for the purchaser under the phi lips i 2 c patent rights to use these components in an i 2 c system, provided that the system conforms to the i 2 c standard specification as defined by philips.

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