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ultralow noise xfet voltage references with current sink and source capability adr430/ adr431/ adr433/ adr434/ adr435/ adr439 rev. j 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 ?2003C2011 analog devices, inc. all rights reserved. features low noise (0.1 hz to 10.0 hz): 3.5 v p-p @ 2.5 v output no external capacitor required low temperature coefficient a grade: 10 ppm/c maximum b grade: 3 ppm/c maximum load regulation: 15 ppm/ma line regulation: 20 ppm/v wide operating range adr430: 4.1 v to 18 v adr431: 4.5 v to 18 v adr433: 5.0 v to 18 v adr434: 6.1 v to 18 v adr435: 7.0 v to 18 v adr439: 6.5 v to 18 v high output source and sink current: +30 ma and ?20 ma wide temperature range: ?40c to +125c applications precision data acquisition systems high resolution data converters medical instruments industrial process control systems optical control circuits precision instruments pin configurations notes 1. nic = no internal connection 2. tp = test pin (do not connect) adr43x top view (not to scale) tp 1 v in 2 nic 3 gnd 4 tp comp v out trim 8 7 6 5 04500-001 figure 1. 8-lead msop (rm-8) notes 1. nic = no internal connection 2. tp = test pin (do not connect) adr43x top view (not to scale) tp 1 v in 2 nic 3 gnd 4 tp comp v out trim 8 7 6 5 04500-041 figure 2. 8-lead soic_n (r-8) general description the adr43x series is a family of xfet? voltage references featuring low 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 adr43x is minimized. the xfet references operate at lower current (800 a) and lower supply voltage headroom (2 v) than buried zener references. buried zener references require more than 5 v headroom for operation. the adr43x xfet references are the only low noise solutions for 5 v systems. the adr43x family has the capability to source up to 30 ma of output current and sink up to 20 ma. it also comes with a trim terminal to adjust the output voltage over a 0.5% range without compromising performance. the adr43x is available in 8-lead msop and 8-lead 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) accuracy (mv) temperature coefficient (ppm/c) adr430a 2.048 3 10 adr430b 2.048 1 3 adr431a 2.500 3 10 adr431b 2.500 1 3 adr433a 3.000 4 10 adr433b 3.000 1.5 3 adr434a 4.096 5 10 adr434b 4.096 1.5 3 adr435a 5.000 6 10 adr435b 5.000 2 3 adr439a 4.500 5.5 10 adr439b 4.500 2 3
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 2 of 24 table of contents features .............................................................................................. 1 ? applications....................................................................................... 1 ? pin configurations ........................................................................... 1 ? general description ......................................................................... 1 ? revision history ............................................................................... 3 ? specifications..................................................................................... 4 ? adr430 electrical ch aracteristics............................................. 4 ? adr431 electrical ch aracteristics............................................. 5 ? adr433 electrical ch aracteristics............................................. 6 ? adr434 electrical ch aracteristics............................................. 7 ? adr435 electrical ch aracteristics............................................. 8 ? adr439 electrical ch aracteristics............................................. 9 ? absolute maximum ratings.......................................................... 10 ? thermal resistance .................................................................... 10 ? esd caution................................................................................ 10 ? typical performance characteristics ........................................... 11 ? theory of operation ...................................................................... 16 ? basic voltage reference connections...................................... 16 ? noise performance ..................................................................... 16 ? high frequency noise ............................................................... 16 ? turn-on time ............................................................................ 17 ? applications information .............................................................. 18 ? output adjustment .................................................................... 18 ? reference for converters in optical network control circuits......................................................................................... 18 ? high voltage floating current source .................................... 18 ? kelvin connection ..................................................................... 18 ? dual polarity references ........................................................... 19 ? programmable current source ................................................ 19 ? programmable dac reference voltage .................................. 20 ? precision voltage reference for data converters.................. 20 ? precision boosted output regulator ....................................... 21 ? outline dimensions ....................................................................... 22 ? ordering guide .......................................................................... 23 ?
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 3 of 24 revision history 7/11rev. i to rev. j changes to figure 1 and figure 2....................................................1 changes to ordering guide...........................................................23 5/11rev. h to rev. i added endnote 1 in table 2.............................................................4 added endnote 1 in table 3.............................................................5 added endnote 1 in table 4.............................................................6 added endnote 1 in table 5.............................................................7 added endnote 1 in table 6.............................................................8 added endnote 1 in table 7.............................................................9 deleted negative precision reference without precision resistors section..............................................................................17 deleted figure 36; renumbered sequentially .............................18 2/11rev. g to rev. h updated outline dimensions........................................................21 changes to ordering guide...........................................................22 7/10rev. f to rev. g changes to storage temperature range in table 9.......................9 6/10rev. e to rev. f updated pin name nc to comp throughout ............................1 changes to figure 1 and figure 2....................................................1 changes to figure 30 and high frequency noise section ........15 updated outline dimensions........................................................21 changes to ordering guide...........................................................22 1/09rev. d to rev. e added high frequency noise section and equation 3; renumbered sequentially ..............................................................15 inserted figure 31, figure 32, and figure 33; renumbered sequentially ......................................................................................16 changes to the ordering guide ....................................................22 12/07rev. c to rev. d changes to initial accuracy and ripple rejection ratio parameters in table 2 through table 7...........................................3 changes to table 9 ............................................................................9 changes to theory of operation section ....................................15 updated outline dimensions........................................................20 8/06rev. b to rev. c updated format ................................................................. universal changes to table 1 ............................................................................1 changes to table 3 ............................................................................4 changes to table 4 ............................................................................5 changes to table 7 ............................................................................8 changes to figure 26 ......................................................................14 changes to figure 31 ......................................................................16 updated outline dimensions........................................................20 changes to ordering guide...........................................................21 9/04rev. a to rev. b added new grade.............................................................. universal changes to specifications ................................................................3 replaced figure 3, figure 4, figure 5 ...........................................10 updated ordering guide ...............................................................21 6/04rev. 0 to rev. a changes to format............................................................. universal changes to the ordering guide ....................................................20 12/03revision 0: initial version
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 4 of 24 specifications adr430 electrical characteristics v in = 4.1 v to 18 v, i l = 0 ma, t a = 25c, 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 1 v oerr a grade 3 mv 0.15 % b grade 1 mv 0.05 % temperature coefficient 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 v in = 4.1 v to 18 v, ?40c < t a < +125c 5 20 ppm/v load regulation ?v o /?i l i l = 0 ma to 10 ma, v in = 5.0 v, ?40c < t a < +125c 15 ppm/ma ?v o /?i l i l = ?10 ma to 0 ma, v in = 5.0 v, ?40c < t a < +125c 15 ppm/ma quiescent current i in no load, ?40c < t a < +125c 560 800 a voltage noise e n p-p 0.1 hz to 10.0 hz 3.5 v p-p voltage noise density e n 1 khz 60 nv/hz turn-on settling time t r c l = 0 f 10 s long-term stability 2 ?v o 1000 hours 40 ppm output voltage hysteresis v o_hys 20 ppm ripple rejection ratio rrr f in = 1 khz C70 db short circuit to gnd i sc 40 ma supply voltage operating range v in 4.1 18 v supply voltage headroom v in ? v o 2 v 1 initial accuracy does not include shift due to solder heat effect. 2 the long-term stability specification is noncumulative. the drift in subsequent 1000 hour periods is sign ificantly lower than in the first 1000 hour period.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 5 of 24 adr431 electrical characteristics v in = 4.5 v to 18 v, i l = 0 ma, t a = 25c, 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 1 v oerr a grade 3 mv 0.12 % b grade 1 mv 0.04 % temperature coefficient 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 v in = 4.5 v to 18 v, ?40c < t a < +125c 5 20 ppm/v load regulation ?v o /?i l i l = 0 ma to 10 ma, v in = 5.0 v, ?40c < t a < +125c 15 ppm/ma ?v o /?i l i l = ?10 ma to 0 ma, v in = 5.0 v, ?40c < t a < +125c 15 ppm/ma quiescent current i in no load, ?40c < t a < +125c 580 800 a voltage noise e n p-p 0.1 hz to 10.0 hz 3.5 v p-p voltage noise density e n 1 khz 80 nv/hz turn-on settling time t r c l = 0 f 10 s long-term stability 2 ?v o 1000 hours 40 ppm output voltage hysteresis v o_hys 20 ppm ripple rejection ratio rrr f in = 1 khz ?70 db short circuit to gnd i sc 40 ma supply voltage operating range v in 4.5 18 v supply voltage headroom v in ? v o 2 v 1 initial accuracy does not include shift due to solder heat effect. 2 the long-term stability specification is noncumulative. the drift in subsequent 1000 hour periods is sign ificantly lower than in the first 1000 hour period.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 6 of 24 adr433 electrical characteristics v in = 5.0 v to 18 v, i l = 0 ma, t a = 25c, 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 2.9985 3.000 3.0015 v initial accuracy 1 v oerr a grade 4 mv 0.13 % b grade 1.5 mv 0.05 % temperature coefficient 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 v in = 5 v to 18 v, ?40c < t a < +125c 5 20 ppm/v load regulation ?v o /?i l i l = 0 ma to 10 ma, v in = 6 v, ?40c < t a < +125c 15 ppm/ma ?v o /?i l i l = ?10 ma to 0 ma, v in = 6 v, ?40c < t a < +125c 15 ppm/ma quiescent current i in no load, ?40c < t a < +125c 590 800 a voltage noise e n p-p 0.1 hz to 10.0 hz 3.75 v p-p voltage noise density e n 1 khz 90 nv/hz turn-on settling time t r c l = 0 f 10 s long-term stability 2 ?v o 1000 hours 40 ppm output voltage hysteresis v o_hys 20 ppm ripple rejection ratio rrr f in = 1 khz ?70 db short circuit to gnd i sc 40 ma supply voltage operating range v in 5.0 18 v supply voltage headroom v in ? v o 2 v 1 initial accuracy does not include shift due to solder heat effect. 2 the long-term stability specification is noncumulative. the drift in subsequent 1000 hour periods is sign ificantly lower than in the first 1000 hour period.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 7 of 24 adr434 electrical characteristics v in = 6.1 v to 18 v, i l = 0 ma, t a = 25c, 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 4.0945 4.096 4.0975 v initial accuracy 1 v oerr a grade 5 mv 0.12 % b grade 1.5 mv 0.04 % temperature coefficient 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 v in = 6.1 v to 18 v, ?40c < t a < +125c 5 20 ppm/v load regulation ?v o /?i l i l = 0 ma to 10 ma, v in = 7 v, ?40c < t a < +125c 15 ppm/ma ?v o /?i l i l = ?10 ma to 0 ma, v in = 7 v, ?40c < t a < +125c 15 ppm/ma quiescent current i in no load, ?40c < t a < +125c 595 800 a voltage noise e n p-p 0.1 hz to 10.0 hz 6.25 v p-p voltage noise density e n 1 khz 100 nv/hz turn-on settling time t r c l = 0 f 10 s long-term stability 2 ?v o 1000 hours 40 ppm output voltage hysteresis v o_hys 20 ppm ripple rejection ratio rrr f in = 1 khz ?70 db short circuit to gnd i sc 40 ma supply voltage operating range v in 6.1 18 v supply voltage headroom v in ? v o 2 v 1 initial accuracy does not include shift due to solder heat effect. 2 the long-term stability specification is noncumulative. the drift in subsequent 1000 hour periods is sign ificantly lower than in the first 1000 hour period.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 8 of 24 adr435 electrical characteristics v in = 7.0 v to 18 v, i l = 0 ma, t a = 25c, 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 1 v oerr a grade 6 mv 0.12 % b grade 2 mv 0.04 % temperature coefficient 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 v in = 7 v to 18 v, ?40c < t a < +125c 5 20 ppm/v load regulation ?v o /?i l i l = 0 ma to 10 ma, v in = 8 v, ?40c < t a < +125c 15 ppm/ma ?v o /?i l i l = ?10 ma to 0 ma, v in = 8 v, ?40c < t a < +125c 15 ppm/ma quiescent current i in no load, ?40c < t a < +125c 620 800 a voltage noise e n p-p 0.1 hz to 10 hz 8 v p-p voltage noise density e n 1 khz 115 nv/hz turn-on settling time t r c l = 0 f 10 s long-term stability 2 ?v o 1000 hours 40 ppm output voltage hysteresis v o_hys 20 ppm ripple rejection ratio rrr f in = 1 khz ?70 db short circuit to gnd i sc 40 ma supply voltage operating range v in 7.0 18 v supply voltage headroom v in ? v o 2 v 1 initial accuracy does not include shift due to solder heat effect. 2 the long-term stability specification is noncumulative. the drift in subsequent 1000 hour periods is sign ificantly lower than in the first 1000 hour period.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 9 of 24 adr439 electrical characteristics v in = 6.5 v to 18 v, i l = 0 mv, t a = 25c, unless otherwise noted. table 7. parameter symbol conditions min typ max unit output voltage v o a grade 4.4946 4.500 4.5054 v b grade 4.498 4.500 4.502 v initial accuracy 1 v oerr a grade 5.5 mv 0.12 % b grade 2 mv 0.04 % temperature coefficient 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 v in = 6.5 v to 18 v, ?40c < t a < +125c 5 20 ppm/v load regulation ?v o /?i l i l = 0 ma to 10 ma, v in = 6.5 v, ?40c < t a < +125c 15 ppm/ma ?v o /?i l i l = ?10 ma to 0 ma, v in = 6.5 v, ?40c < t a < +125c 15 ppm/ma quiescent current i in no load, ?40c < t a < +125c 600 800 a voltage noise e n p-p 0.1 hz to 10.0 hz 7.5 v p-p voltage noise density e n 1 khz 110 nv/hz turn-on settling time t r c l = 0 f 10 s long-term stability 2 ?v o 1000 hours 40 ppm output voltage hysteresis v o_hys 20 ppm ripple rejection ratio rrr f in = 1 khz ?70 db short circuit to gnd i sc 40 ma supply voltage operating range v in 6.5 18 v supply voltage headroom v in ? v o 2 v 1 initial accuracy does not include shift due to solder heat effect. 2 the long-term stability specification is noncumulative. the drift in subsequent 1000 hour periods is sign ificantly lower than in the first 1000 hour period.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 10 of 24 absolute maximum ratings t a = 25c, unless otherwise noted. table 8. parameter rating supply voltage 20 v output short-circuit duration to gnd indefinite storage temperature range ?65c to +150c 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 9. thermal resistance package type ja jc unit 8-lead soic_n (r) 130 43 c/w 8-lead msop (rm) 142 44 c/w esd caution
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 11 of 24 typical performance characteristics default conditions: 5 v, c l = 5 pf, g = 2, r g = r f = 1 k, r l = 2 k, v o = 2 v p-p, f = 1 mhz, t a = 25c, unless otherwise noted. 2.4995 output voltage (v) 2.5009 2.5007 2.5005 2.5003 2.5001 2.4999 2.4997 temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 04500-015 figure 3. adr431 output voltage vs. temperature output vol t age (v) temperature ( c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 4.0950 4.0980 4.0975 4.0970 4.0965 4.0960 4.0955 04500-016 figure 4. adr434 output voltage vs. temperature output vol t age (v) temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 4.9990 5.0025 5.0020 5.0015 5.0010 5.0005 5.0000 4.9995 04500-017 figure 5. adr435 output voltage vs. temperature 0.3 0.4 0.5 0.6 0.7 0.8 supply current (ma) 810 4 6 12 14 16 input voltage (v) +125c +25c ?40c 04500-018 figure 6. adr435 supply current vs. input voltage 400 450 500 550 600 650 700 supply current (a) temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 04500-019 figure 7. adr435 supply current vs. temperature 0.40 0.42 0.44 0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60 supply current (ma) 10 12 6 8 14 16 18 input voltage (v) +125c +25c ?40c 04500-020 figure 8. adr431 supply current vs. input voltage
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 12 of 24 400 430 460 490 520 550 580 610 supply current (a) temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 04500-021 figure 9. adr431 supply current vs. temperature 0 3 6 9 12 15 load regul a tion (ppm/ma) i l = 0ma to 10ma temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 04500-022 figure 10. adr431 load regulation vs. temperature 0 3 6 9 12 15 load regul a tion (ppm/ma) i l = 0ma to 10ma temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 04500-023 figure 11. adr435 load regulation vs. temperature 0 0.5 1.0 1.5 2.0 2.5 differential voltage (v) load current (ma) ?5 ?10 0 5 10 ?40c +25c +125c 04500-024 figure 12. adr431 minimum input/output differential voltage vs. load current 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 minimum headroom (v) temperature (c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 no load 04500-025 figure 13. adr431 minimum headroom vs. temperature 0 0.5 1.0 1.5 2.0 2.5 differenti a l voltage (v) load current (ma) ?5 ?10 0 5 10 ?40c +25c +125c 04500-026 figure 14. adr435 minimum input/output differential voltage vs. load current
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 13 of 24 0.9 1.1 1.3 1.5 1.7 1.9 minimum headroom (v) temperature ( c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 no load 04500-027 figure 15. adr435 minimum headroom vs. temperature ?4 0 4 8 12 16 20 line regul a tion (ppm/v) v in =7vto18v temperature ( c) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 04500-028 figure 16. adr435 line regulation vs. temperature c in = 0.01f no load v o = 1v/div v in = 2v/div time = 4s/div 0 4500-030 figure 17. adr431 turn-on response c l = 0.01f no input capacitor v o = 1v/div v in = 2v/div time = 4s/div 04500-031 figure 18. adr431 turn-on resp onse, 0.01 f load capacitor c in = 0.01f no load v o = 1v/div v in = 2v/div time = 4s/div 0 4500-032 figure 19. adr431 turn-off response bypass capacitor = 0f v o = 50mv/div time = 100s/div line interruption v in = 500mv/div 04500-033 figure 20. adr431 line transient response
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 14 of 24 bypass capacitor = 0.1f v o = 50mv/div time = 100s/div line interruption v in = 500mv/div 04500-034 figure 21. adr431 line transient response, 0.1 f bypass capacitor 1v/div time = 1s/div 04500-035 figure 22. adr431 0.1 hz to 10.0 hz voltage noise time = 1s/div 50v/div 04500-036 figure 23. adr431 10 hz to 10 khz voltage noise time = 1s/div 2v/div 04500-037 figure 24. adr435 0.1 hz to 10.0 hz voltage noise time = 1s/div 50v/div 04500-038 figure 25. adr435 10 hz to 10 khz voltage noise 0 2 4 6 8 10 12 14 number of parts deviation (ppm) ?110 ?90 ?70 ?50 ?30 ?10 10 30 50 70 90 110 04500-029 figure 26. adr431 typical hysteresis
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 15 of 24 0 5 10 15 20 25 30 35 40 45 50 output impedance ( ) frequency (hz) 100 10k 1k 100k adr435 a d r 4 3 3 adr430 04500-039 figure 27. output im pedance vs. frequency ?150 ?130 ?110 ?90 ?70 ?50 ripple rejection (db) ?30 ?10 10 10 100 1k 10k 100k 1m frequency (hz) 04500-040 figure 28. ripple rejection
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 16 of 24 theory of operation the adr43x series of references uses a reference generation technique known as xfet (extra implanted junction fet). this technique yields a reference with low supply current, 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 ?120 ppm/c. this slope is essentially constant to the dielectric constant of silicon and can be compensated closely by adding a correction term generated in the same fashion as the proportional-to-temperature (ptat) term used to compensate band gap references. the primary advantage of an xfet reference is its correction term, which is ~30 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 29 shows the basic topology of the adr43x 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 v out = g ( v p C r1 i ptat ) (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. adr43x devices are created by on-chip adjustment of r2 and r3 to achieve 2.048 v or 2.500 v, respectively, 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 adr43x 04500-002 figure 29. simplified schematic device power dissipation considerations the adr43x family of references is guaranteed to deliver load currents to 10 ma with an input voltage that ranges from 4.1 v to 18 v. when these devices are used in applications at higher currents, use the following equation to account for the temperature effects due to the power dissipation increases: t j = p d ja + t a (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 voltage reference connections voltage references, in general, require a bypass capacitor connected from v out to gnd. the circuit in figure 30 illustrates the basic configuration for the adr43x family of references. other than a 0.1 f capacitor at the output to help improve noise suppression, a large output capacitor at the output is not required for circuit stability. + notes: 1. nc = no connect 2. tp = test pin (do not connect) 1 2 3 45 8 6 7 adr43x top view (not to scale) tp comp v out trim tp nc gnd v in 10f 0.1f 0.1f 04500-044 figure 30. basic voltage reference configuration noise performance the noise generated by the adr43x family of references is typically less than 3.75 v p-p over the 0.1 hz to 10.0 hz band for adr430, adr431, and adr433. figure 22 shows the 0.1 hz to 10.0 hz noise of the adr431, which is only 3.5 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. high frequency noise the total noise generated by the adr43x family of references is composed of the reference noise and the op amp noise. figure 31 shows the wideband noise from 10 hz to 25 khz. an internal node of the op amp is brought out on pin 7, and by overcompensating the op amp, the overall noise can be reduced. this is understood by considering that in a closed-loop configuration, the effective output impedance of an op amp is e vo o o a r r 1 (3) where: r o is the apparent output impedance. r o is the output resistance of the op amp. a vo is the open-loop gain at the frequency of interest. is the feedback factor.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 17 of 24 equation 3 shows that the apparent output impedance is reduced by approximately the excess loop gain; therefore, as the frequency increases, the excess loop gain decreases, and the apparent output impedance increases. a passive element whose impedance increases as its frequency increases is an inductor. when a capacitor is added to the output of an op amp or a reference, it forms a tuned circuit that resonates at a certain frequency and results in gain peaking. this can be observed by using a model of a semiperfect op amp with a single-pole response and some pure resistance in series with the output. changing capacitive loads results in peaking at different frequencies. for most normal op amp applications with low capacitive loading (<100 pf), this effect is usually not observed. however, references are used increasingly to drive the reference input of an adc that may present a dynamic, switching capacitive load. large capacitors, in the microfarad range, are used to reduce the change in reference voltage to less than one-half lsb. figure 31 shows the adr431 noise spectrum with various capacitive values to 50 f. with no capacitive load, the noise spectrum is relatively flat at approximately 60 nv/hz to 70 nv/hz. with various values of capacitive loading, the predicted noise peaking becomes evident. 10 100 1000 10 100 1k 10k 100k adr431 no compensation c l = 0f c l = 1f c l = 50f c l = 10f 04500-042 frequency (hz) noise density (nv/ hz) figure 31. noise vs. capacitive loading the op amp within the adr43x family uses the classic rc compensation technique. monolithic capacitors in an ic are limited to tens of picofarads. with very large external capacitive loads, such as 50 f, it is necessary to overcompensate the op amp. the internal compensation node is brought out on pin 7, and an external series rc network can be added between pin 7 and the output, pin 6, as shown in figure 32 . + notes 1. nc = no connec t 2 . tp = test pin (do not connect) 1 2 3 4 5 8 6 7 adr43x top view (not to scale) tp comp v out trim tp nc gnd v in 10f 0.1f 0.1f 04500-003 82k ? 10nf figure 32. compensated reference the 82 k resistor and 10 nf capacitor can eliminate the noise peaking (see figure 33 ). the comp pin should be left unconnected if unused. 10 100 10 100 1k 10k 04500-043 frequency (hz) noise density (nv/ hz) c l = 1f rc 82k ? and 10nf c l = 10f rc 82k ? and 10nf c l = 50f rc 82k ? and 10nf figure 33. noise with compensation network 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 components 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 17 and figure 18 show the turn-on settling time for the adr431.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 18 of 24 applications information output adjustment the adr43x trim terminal can be used to adjust the output voltage over a 0.5% range. this feature allows the system designer to trim system errors out by setting the reference to a voltage other than the nominal. this is also helpful if the part is used in a system at temperature to trim out any error. adjustment of the output has negligible effect on the temperature performance of the device. to avoid degrading temperature coefficients, both the trimming potentiometer and the two resistors need to be low temperature coefficient types, preferably <100 ppm/c. input output trim v in v o = 0.5% gnd r1 470k ? r2 10k ? (adr430) 15k ? (adr431) r p 10k? adr43x v out 0 4500-004 figure 34. output trim adjustment reference for converters in optical network control circuits in figure 35 , the high capacity, all optical router network employs arrays of micromirrors to direct and route optical signals from fiber to fiber without first converting them to electrical form, which reduces the communication speed. the tiny micromechanical mirrors are positioned so that each is illuminated by a single wavelength that carries unique information and can be passed to any desired input and output fiber. the mirrors are tilted by the dual-axis actuators, which are controlled by precision adcs and dacs within the system. due to the microscopic movement of the mirrors, not only is the precision of the converters important but the noise associated with these controlling converters is also extremely critical. total noise within the system can be multiplied by the number of converters employed. therefore, to maintain the stability of the control loop for this application, the adr43x, with its exceptionally low noise, is necessary. gnd source fiber gimbal + sensor destination fiber activator right mems mirror laser beam activator left ampl preamp ampl control electronics dac adc dac dsp adr431 adr431 adr431 04500-005 figure 35. all optical router network high voltage floating current source the circuit in figure 36 can be used 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. v in v out gnd op90 + v s sst111 vishay 2n3904 r l 2.1k ? ?v s adr43x 2 6 4 04500-007 figure 36. high voltage floating current source kelvin connection in many portable instrumentation applications, where printed circuit board (pcb) cost and area go hand in hand, circuit interconnects are very often of dimensionally minimum width. these narrow lines can cause large voltage drops if the voltage reference is required to provide load currents to various functions. in fact, circuit interconnects can exhibit a typical line resistance of 0.45 m/square (for example, 1 oz. cu). force and sense connections, also referred to as kelvin connections, offer a convenient method of eliminating the effects of voltage drops in circuit wires. load currents flowing through wiring resistance produce an error (v error = r i l ) at the load. however, the kelvin connection of figure 37 overcomes the problem by including the wiring resistance within the forcing loop of the operational amplifier. because the amplifier senses the load voltage, the operational amplifier loop control forces the output to compensate for the wiring error and to produce the correct voltage at the load.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 19 of 24 v in v out gnd r lw r l v out sense v out force r lw v in 2 6 4 adr43x a1 op191 + 04500-008 figure 37. advantage of kelvin connection dual polarity references dual polarity references can easily be made with an operational amplifier and a pair of resistors. to avoid defeating the accuracy obtained by the adr43x, it is imperative to match the resistance tolerance as well as the temperature coefficient of all the components. 6 2 4 5 ? 10v v in v in v out gnd trim r1 r2 u2 r3 v+ v? +10v ?5v +5v 10k ? 1f 0.1f u1 adr435 op1177 5k? 10k? 04500-009 figure 38. +5 v and ?5 v references using adr435 6 2 4 5 v in v out gnd trim r1 5.6k ? u2 v+ v? +10v u1 adr435 op1177 +2.5 v ?2.5v r2 5.6k ? ?10v 04500-010 figure 39. +2.5 v and ?2.5 v references using adr435 programmable current source together with a digital potentiometer and a howland current pump, the adr435 forms the reference source for a programmable current as w b b a l v r r1 rr2 i 2 2 (4) and ref n w v d v 2 (5) where: d is the decimal equivalent of the input code. n is the number of bits. in addition, r1' and r2' must be equal to r1 and (r2 a + r2 b ), respectively. in theory, r2 b can be made as small as needed to achieve the necessary current within the a2 output current driving capability. in this example, the op2177 can deliver a maximum output current of 10 ma. because the current pump employs both positive and negative feedback, c1 and c2 capacitors are needed to ensure that the negative feedback prevails and, therefore, avoids oscillation. this circuit also allows bidirectional current flow if the v a and v b inputs of the digital potentiometer are supplied with the dual polarity references, as shown in figure 40 . 6 2 4 5 v in v dd v out gnd trim c2 10pf u1 v+ v? i l adr435 op2177 r1 50k ? op2177 v? v+ a2 a1 i l v dd u2 ad5232 w a b v ss r1' 50k ? r2' 1k ? r2 a 1k? r2 b 10 ? v dd v ss c1 10pf + vl ? 04500-011 figure 40. programmable current source
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 20 of 24 programmable dac reference voltage by employing a multichannel dac, such as the ad7398, quad, 12-bit voltage output dac, one of its internal dacs and an adr43x voltage reference can be used as a common programmable v refx for the rest of the dacs. the circuit configuration is shown in figure 41 . v refa dac a v refb dac b v refc dac c v refd dac d v outa v outb v outc v outd v ob =v refx (d b ) v oc =v refx (d c ) v od =v refx (d d ) adr43x ad7398 v in v ref r1 0.1% r2 0.1% 04500-012 figure 41. programmable dac reference the relationship of v refx to v ref depends on the digital code and the ratio of r1 and r2, given by ? ? ? ? ? ? + ? ? ? ? ? ? + = r1 r2d r1 r2 v v n ref refx 2 1 1 (6) where: d is the decimal equivalent of the input code. n is the number of bits. v ref is the applied external reference. v refx is the reference voltage for dac a to dac d. table 10. v refx vs. r1 and r2 r1, r2 digital code v ref r1 = r2 0000 0000 0000 2 v ref r1 = r2 1000 0000 0000 1.3 v ref r1 = r2 1111 1111 1111 v ref r1 = 3r2 0000 0000 0000 4 v ref r1 = 3r2 1000 0000 0000 1.6 v ref r1 = 3r2 1111 1111 1111 v ref precision voltage reference for data converters the adr43x family has a number of features that make it ideal for use with adcs and dacs. the exceptional low noise, tight temperature coefficient, and high accuracy characteristics make the adr43x ideal for low noise applications, such as cellular base station applications. another example of an adc for which the adr431 is well suited is the ad7701. figure 42 shows the adr431 used as the precision reference for this converter. the ad7701 is a 16-bit adc with on-chip digital filtering intended for the measurement of wide dynamic range and low frequency signals, such as those representing chemical, physical, or biological processes. it contains a charge-balancing - adc, a calibration microcontroller with on-chip static ram, a clock oscillator, and a serial communications port. serial clock read (transmit) data ready +5 v a nalo g supply serial clock ranges select calibrate analog input analog ground ?5v analog supply dv dd sleep mode drdy cs sclk sdata clkin clkout sc1 sc2 dgnd dv ss av ss agnd a in cal bp/up v ref av dd v in v out gnd adr431 ad7701 0.1f 0.1f 0.1f 0.1f 10f 0.1f 10f 0.1f 2 6 4 04500-013 figure 42. voltage reference for the ad7701 16-bit adc
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 21 of 24 v? v+ + ? v in n1 v in v out trim gnd 5v u2 2n7002 ad8601 u1 adr431 v o r l 25 ? 2 6 5 4 04500-014 precision boosted output regulator a precision voltage output with boosted current capability can be realized with the circuit shown in figure 43 . in this circuit, u2 forces v o to be equal to v ref by regulating the turn-on of n1. therefore, the load current is furnished by v in . in this configuration, a 50 ma load is achievable at a v in of 5 v. moderate heat is generated on the mosfet, and higher current can be achieved with a replacement of the larger device. in addition, for a heavy capacitive load with step input, a buffer can be added at the output to enhance the transient response. figure 43. precision bo osted output regulator
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 22 of 24 outline dimensions compliant to jedec standards mo-187-aa 6 0 0.80 0.55 0.40 4 8 1 5 0.65 bsc 0.40 0.25 1.10 max 3.20 3.00 2.80 coplanarity 0.10 0.23 0.09 3.20 3.00 2.80 5.15 4.90 4.65 pin 1 identifier 15 max 0.95 0.85 0.75 0.15 0.05 10-07-2009-b figure 44. 8-lead mini small outline package [msop] (rm-8) dimensions shown in millimeters 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 012407-a 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 (0.2441) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarity 0.10 figure 45. 8-lead standard small outline package [soic_n] narrow body (r-8) dimensions shown in millimeters and (inches)
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 23 of 24 ordering guide initial accuracy, model 1 output voltage (v) (mv) (%) temperature coefficient package (ppm/c) temperature range package description package option ordering quantity branding adr430arz 2.048 3 0.15 10 ?40c to +125c 8-lead soic_n r-8 98 adr430arz-reel7 2.048 3 0.15 10 ?40c to +125c 8-lead soic_n r-8 1,000 adr430armz 2.048 3 0.15 10 ?40c to +125c 8-lead msop rm-8 50 r10 adr430armz-reel7 2.048 3 0.15 10 ?40c to +125c 8-lead msop rm-8 1,000 r10 adr430brz 2.048 1 0.05 3 ?40c to +125c 8-lead soic_n r-8 98 adr430brz-reel7 2.048 1 0.05 3 ?40c to +125c 8-lead soic_n r-8 1,000 adr431arz 2.500 3 0.12 10 ?40c to +125c 8-lead soic_n r-8 98 adr431arz-reel7 2.500 3 0.12 10 ?40c to +125c 8-lead soic_n r-8 1,000 adr431armz 2.500 3 0.12 10 ?40c to +125c 8-lead msop rm-8 50 r12 adr431armz-reel7 2.500 3 0.12 10 ?40c to +125c 8-lead msop rm-8 1,000 r12 adr431br 2.500 1 0.04 3 ?40c to +125c 8-lead soic_n r-8 98 adr431br-reel7 2.500 1 0.04 3 ?40c to +125c 8-lead soic_n r-8 1,000 adr431brz 2.500 1 0.04 3 ?40c to +125c 8-lead soic_n r-8 98 adr431brz-reel7 2.500 1 0.04 3 ?40c to +125c 8-lead soic_n r-8 1,000 adr433arz 3.000 4 0.13 10 ?40c to +125c 8-lead soic_n r-8 98 adr433arz-reel7 3.000 4 0.13 10 ?40c to +125c 8-lead soic_n r-8 1,000 ADR433ARMZ 3.000 4 0.13 10 ?40c to +125c 8-lead msop rm-8 50 r14 ADR433ARMZ-reel7 3.000 4 0.13 10 ?40c to +125c 8-lead msop rm-8 1,000 r14 adr433brz 3.000 1.5 0.05 3 ?40c to +125c 8-lead soic_n r-8 98 adr433brz-reel7 3.000 1.5 0.05 3 ?40c to +125c 8-lead soic_n r-8 1,000 adr434arz 4.096 5 0.12 10 ?40c to +125c 8-lead soic_n r-8 98 adr434arz-reel7 4.096 5 0.12 10 ?40c to +125c 8-lead soic_n r-8 1,000 adr434armz 4.096 5 0.12 10 ?40c to +125c 8-lead msop rm-8 50 r16 adr434armz-reel7 4.096 5 0.12 10 ?40c to +125c 8-lead msop rm-8 1,000 r16 adr434brz 4.096 1.5 0.04 3 ?40c to +125c 8-lead soic_n r-8 98 adr434brz-reel7 4.096 1.5 0.04 3 ?40c to +125c 8-lead soic_n r-8 1,000 adr435arz 5.000 6 0.12 10 C40c to +125c 8-lead soic_n r-8 98 adr435arz-reel7 5.000 6 0.12 10 C40c to +125c 8-lead soic_n r-8 1,000 adr435armz 5.000 6 0.12 10 C40c to +125c 8-lead msop rm-8 50 r18 adr435armz-reel7 5.000 6 0.12 10 C40c to +125c 8-lead msop rm-8 1,000 r18 adr435brmz 5.000 2 0.04 3 C40c to +125c 8-lead msop rm-8 50 r19 adr435brmz-r7 5.000 2 0.04 3 C40c to +125c 8-lead msop rm-8 1,000 r19 adr435brz 5.000 2 0.04 3 C40c to +125c 8-lead soic_n r-8 98 adr435brz-reel7 5.000 2 0.04 3 C40c to +125c 8-lead soic_n r-8 1,000 adr439arz-reel7 4.500 5.5 0.12 10 C40c to +125c 8-lead soic_n r-8 1,000 adr439armz-reel7 4.500 5.5 0.12 10 C40c to +125c 8-lead msop rm-8 1,000 r1c adr439brz-reel7 4.500 2 0.04 3 C40c to +125c 8-lead soic_n r-8 1,000 1 z = rohs compliant part.
adr430/adr431/adr433/adr434/adr435/adr439 rev. j | page 24 of 24 notes ?2003C2011 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d04500-0-7/11(j)

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