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10 a, rail-to-rail i/o, zero input crossover distortion amplifiers ADA4505-1/ada4505-2/ada4505-4 rev. d 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 ?2008C20 10 analog devices, inc. all rights reserved. supplies. features psrr: 100 db minimum cmrr: 105 db typical very low supply current: 10 a per amplifier maximum 1.8 v to 5 v single-supply or 0.9 v to 2.5 v dual-supply operation rail-to-rail input and output 3 mv offset voltage maximum very low input bias current: 0.5 pa typical applications pressure and position sensors remote security medical monitors battery-powered consumer equipment hazard detectors general description the ADA4505-1/ada4505-2/ada4505-4 are single, dual, and quad micropower amplifiers featuring rail-to-rail input and output swings while operating from a single 1.8 v to 5 v power supply or from dual 0.9 v to 2.5 v power supplies. employing a new circuit technology, these low cost amplifiers offer zero input crossover distortion (excellent psrr and cmrr performance) and very low bias current, while operating with a supply current of less than 10 a per amplifier. this combination of features makes the ada4505-x amplifiers ideal choices for battery-powered applications because they minimize errors due to power supply voltage variations over the lifetime of the battery and maintain high cmrr even for a rail- to-rail op amp. remote battery-powered sensors, handheld instrumentation and consumer equipment, hazard detectors (for example, smoke, fire, and gas), and patient monitors can benefit from the features of the ada4505-x amplifiers. the ada4505-x family is specified for both the industrial temperature range (?40c to +85c) and the extended industrial temperature range (?40c to +125c). the ADA4505-1 single amplifier is available in a tiny 5-lead sot-23 and a 6-ball wlcsp. the ada4505-2 dual amplifier is available in a standard 8-lead msop and a 8-ball wlcsp. the ada4505-4 quad amplifier is available in a 14-lead tssop and a 14-ball wlcsp. the ada4505-x family is a member of a growing series of zero crossover op amps offered by analog devices, inc., including the ad8505/ ad8506/ ad8508 , which also operate from a single 1.8 v to 5 v power supply or from dual 0.9 v to 2.5 v power pin configurations out 1 +in 3 v? 2 v+ 5 ?in 4 ADA4505-1 top view (not to scale) 07416-001 07416-004 out a 1 ?in a 2 +in a 3 v? 4 v+ 8 out b 7 ?in b 6 +in b 5 ada4505-2 top view (not to scale) figure 1. 5-lead sot-23 (rj-5) figure 2. 8-lead msop (rm-8) 07416-068 out v+ v? +in ?in top view (ball side down) not to scale a1 a2 b1 b2 c1 c2 ball a 1 indic ator nc ADA4505-1 nc = no connect 0 7416-003 ada4505-2 top view (ball side down) ball a1 corner out b v+ out a a1 a2 a3 +in b v? +in a c1 c2 c3 ?in b ?in a b1 b3 figure 3. 6-ball wlcsp (cb-6-7) figure 4. 8-ball wlcsp (cb-8-2) 07416-005 ada4505-4 1 2 3 4 5 6 7 ?in a +in a v+ o ut b ?in b +i n b o ut a 14 13 12 11 10 9 8 ?in d +in d v? out c ?in c +in c out d top view (not to scale) ada4505-4 top view (ball side down) not to scale 07416-061 c1 c3 a1 b1 d1 e1 a2 b2 d2 e2 a3 b3 d3 e3 ball a 1 indic ator out d out a ?in a ?in d v? +in a +in d +in b +in c v+ ?in b ?in c out c out b figure 5. 14-lead tssop (ru-14) figure 6. 14-ball wlcsp (cb-14-1)
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 2 of 24 table of contents features .............................................................................................. 1 ? applications ....................................................................................... 1 ? general description ......................................................................... 1 ? pin configurations ........................................................................... 1 ? revision history ............................................................................... 2 ? specifications ..................................................................................... 3 ? electrical characteristics1.8 v operation ............................ 3 ? electrical characteristics5 v operation................................ 4 ? absolute maximum ratings ............................................................ 5 ? thermal resistance ...................................................................... 5 ? esd caution...................................................................................5 ? typical performance characteristics ..............................................6 ? theory of operation ...................................................................... 14 ? applications information .............................................................. 16 ? pulse oximeter current source ............................................... 16 ? four-pole, low-pass butterworth filter for glucose monitor ....................................................................................................... 17 ? outline dimensions ....................................................................... 18 ? ordering guide .......................................................................... 21 ? revision history 7/10 rev. c to rev. d added 6-ball wlcsp, ADA4505-1 .................................. universal moved electrical characteristics1.8 v operation section .... 3 changes to large signal voltage gain parameter, table 1 .......... 3 moved electrical characteristics5 v operation section ....... 4 changes to large signal voltage gain parameter, table 2 .......... 4 changes to thermal resistance section and table 4 ................... 5 updated outline dimensions ....................................................... 18 changes to ordering guide .......................................................... 21 7/09rev. b to rev. c added 5-lead sot-23 (ADA4505-1) ......................... throughout changes to supply current per amplifier parameter, table 1 ... 3 changes to supply current per amplifier parameter, table 2 ... 4 changes to figure 26 and figure 29 ............................................... 9 changes to figure 31 and figure 34 ............................................. 10 changes to figure 42 and figure 45 ............................................. 12 added figure 49 and figure 51; renumbered sequentially ..... 13 updated outline dimensions ....................................................... 18 changes to ordering guide .......................................................... 20 2/09rev. a to rev. b added 14-ball wlcsp (ada4505-4) ........................ throughout changes to thermal resistance section ........................................ 5 changes to figure 17, figure 18, figure 20, and figure 21 ......... 8 changes to figure 42 and figure 45 ............................................. 12 updated outline dimensions ....................................................... 18 changes to ordering guide .......................................................... 20 10/08rev. 0 to rev. a added 8-ball wlcsp (ada4 505-2) and 14-lead tssop (ada4505-4) ................................................................. throughout change to features section .............................................................. 1 added figure 2 and figure 3; renumbered sequentially ............ 1 changes to table 1 ............................................................................. 3 changes to table 2 ............................................................................. 4 changes to thermal resistance section ........................................ 5 changes to figure 22 and figure 25................................................ 9 changes to figure 40 and figure 43............................................. 12 deleted figure 46 and figure 48; renumbered sequentially ... 13 change to theory of operation section ..................................... 14 changes to figure 52 ...................................................................... 16 change to four-pole low-pass butterworth filter for glucose monitor section ......................................................... 17 updated outline dimensions ....................................................... 18 changes to ordering guide .......................................................... 19 7/08revision 0: initial version
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 3 of 24 specifications electrical characteristics1.8 v operation v sy = 1.8 v, v cm = v sy /2, t a = 25c, r l = 100 k to gnd, unless otherwise specified. table 1. parameter symbol test conditions/comments min typ max unit input characteristics offset voltage v os 0 v v cm 1.8 v 0.5 3 mv ?40c t a +125c 4 mv input bias current i b 0.5 2 pa ?40c t a +85c 50 pa ?40c t a +125c 375 pa input offset current i os 0.05 1 pa ?40c t a +85c 25 pa ?40c t a +125c 130 pa input voltage range ?40c t a +125c 0 1.8 v common-mode rejection ratio cmrr 0 v v cm 1.8 v 85 100 db ?40c t a +85c 85 db ?40c t a +125c 80 db large signal voltage gain a vo 0.05 v v out 1.75 v, r l = 100 k to v cm 95 115 db ?40c t a +125c 95 db offset voltage drift v os / t ?40c t a +125c 2.5 v/c input resistance r in 220 g input capacitance differential mode c indm 2.5 pf input capacitance common mode c incm 4.7 pf output characteristics output voltage high v oh r l = 100 k to gnd 1.78 1.79 v ?40c t a +125c 1.78 v r l = 10 k to gnd 1.65 1.75 v ?40c t a +125c 1.65 v output voltage low v ol r l = 100 k to v sy 2 5 mv ?40c t a +125c 5 mv r l = 10 k to v sy 12 25 mv ?40c t a +125c 25 mv short-circuit limit i sc v out = v sy or gnd 3.8 ma power supply power supply rejection ratio psrr v sy = 1.8 v to 5 v 100 110 db ?40c t a +85c 100 db ?40c t a +125c 95 db supply current per amplifier i sy v out = v sy /2 ADA4505-1 10 11.5 a C40c t a +125c 15 a ada4505-2/ada4505-4 7 10 a ?40c t a +125c 15 a dynamic performance slew rate sr r l = 100 k, c l = 20 pf, g = 1 6.5 mv/s gain bandwidth product gbp r l = 1 m, c l = 20 pf, g = 1 50 khz phase margin m r l = 1 m, c l = 20 pf, g = 1 52 degrees noise performance voltage noise e n p-p f = 0.1 hz to 10 hz 2.95 v p-p voltage noise density e n f = 1 khz 65 nv/hz current noise density i n f = 1 khz 20 fa/hz
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 4 of 24 electrical characteristics5 v operation v sy = 5 v, v cm = v sy /2, t a = 25c, r l = 100 k to gnd, unless otherwise specified. table 2. parameter symbol test conditions/comments min typ max unit input characteristics offset voltage v os 0 v v cm 5 v 0.5 3 mv ?40c t a +125c 4 mv input bias current i b 0.5 2 pa ?40c t a +85c 50 pa ?40c t a +125c 375 pa input offset current i os 0.05 1 pa ?40c t a +85c 25 pa ?40c t a +125c 130 pa input voltage range ?40c t a +125c 0 5 v common-mode rejection ratio cmrr 0 v v cm 5 v 90 105 db ?40c t a +85c 90 db ?40c t a +125c 85 db large signal voltage gain a vo 0.05 v v out 4.95 v, r l = 100 k to v cm 105 120 db ?40c t a +125c 100 db offset voltage drift v os / t ?40c t a +125c 2 v/c input resistance r in 220 g input capacitance differential mode c indm 2.5 pf input capacitance common mode c incm 4.7 pf output characteristics output voltage high v oh r l = 100 k to gnd 4.98 4.99 v ?40c t a +125c 4.98 v r l = 10 k to gnd 4.9 4.95 v ?40c t a +125c 4.9 v output voltage low v ol r l = 100 k to v sy 2 5 mv ?40c t a +125c 5 mv r l = 10 k to v sy 10 25 mv ?40c t a +125c 25 mv short-circuit limit i sc v out = v sy or gnd 40 ma power supply power supply rejection ratio psrr v sy = 1.8 v to 5 v 100 110 db ?40c t a +85c 100 db ?40c t a +125c 95 db supply current per amplifier i sy v out = v sy /2 ADA4505-1 9 10.5 a C40c t a +125c 15 a ada4505-2/ada4505-4 7 10 a ?40c t a +125c 15 a dynamic performance slew rate sr r l = 100 k, c l = 20 pf, g = 1 6 mv/s gain bandwidth product gbp r l = 1 m, c l = 20 pf, g = 1 50 khz phase margin m r l = 1 m, c l = 20 pf, g = 1 52 degrees noise performance voltage noise e n p-p f = 0.1 hz to 10 hz 2.95 v p-p voltage noise density e n f = 1 khz 65 nv/hz current noise density i n f = 1 khz 20 fa/hz
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 5 of 24 absolute maximum ratings thermal resistance table 3. parameter rating supply voltage 5.5 v input voltage v sy 0.1 v input current 1 10 ma differential input voltage 2 v sy 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 ja is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages with its exposed paddle soldered to a pad (if applicable). simulated thermal numbers on a 4-layer (2s/2p) jedec standard thermal test board, unless otherwise specified. table 4. package type ja jc unit 5-lead sot-23 (rj-5) 190 92 c/w 6-ball wlcsp (cb-6-7) 105 2.6 c/w 8-lead msop (rm-8) 142 45 c/w 8-ball wlcsp (cb-8-2) 82 n/a c/w 14-lead tssop (ru-14) 112 35 c/w 14-ball wlcsp (cb-14-1) 64 n/a c/w 1 input pins have clamp diodes to the supply pins. limit input current to 10 ma or less whenever the input signal exceeds the power supply rail by 0.1 v. 2 differential input voltage is limited to 5 v or the supply voltage, whichever is less. 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. esd caution
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 6 of 24 typical performance characteristics t a = 25c, unless otherwise noted. 140 120 100 80 60 40 20 0 number of amplifiers ?3.0 ?2.5 ?2.0 ?1.5 ?1.0 ?0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 v os (mv) 07416-007 v sy = 1.8v v cm = v sy /2 figure 7. input offset voltage distribution 14 12 10 8 6 4 2 0 number of amplifiers v sy = 1.8v ?40c t a 125c 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 tcv os (v/c) 07416-009 figure 8. input offset voltage drift distribution 1500 1000 500 0 ?500 ?1000 ?1500 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 v cm (v) v os (v) 07416-011 v sy = 1.8v device 1 device 2 device 3 device 4 device 5 device 6 device 7 device 8 device 9 device 10 figure 9. input offset voltage vs. common-mode voltage 140 120 100 80 60 40 20 0 number of amplifiers ?3.0 ?2.5 ?2.0 ?1.5 ?1.0 ?0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 v os (mv) 07416-008 v sy = 5v v cm = v sy /2 figure 10. input offset voltage distribution 14 12 10 8 6 4 2 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 tcv os (v/c) number of amplifiers 07416-010 v sy = 5v ?40c t a 125c figure 11. input offset voltage drift distribution 1500 1000 500 0 ?500 ?1000 ?1500 012345 v cm (v) v os (v) 07416-012 device 1 device 2 device 3 device 4 device 5 device 6 device 7 device 8 device 9 device 10 v sy = 5v figure 12. input offset voltage vs. common-mode voltage
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 7 of 24 t a = 25c, unless otherwise noted. 1000 100 10 1 0.1 0 25 50 75 100 125 temperature (c) i b (pa) 07416-013 v sy = 1.8v i b+ i b? figure 13. input bias current vs. temperature 1000 100 10 1 0.1 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 v cm (v) i b (pa) 07416-014 v sy = 1.8v i b+ and i b? 125c 105c 85c 25c figure 14. input bias current vs. common-mode voltage and temperature 10k 1k 100 10 1 0.1 0.01 0.001 0.01 0.1 load current (ma) 11 01 output voltage (v oh ) to supply rail (mv) 07416-017 0 0 v sy = 1.8v ?40c +25c +85c +125c figure 15. output voltage (v oh ) to supply rail vs. load current and temperature 1000 100 10 1 0.1 0 25 50 75 100 125 temperature (c) i b (pa) 07416-015 v sy = 5v i b+ i b? figure 16. input bias current vs. temperature 1000 100 10 1 0.1 012 345 v cm (v) i b (pa) 07416-016 125c 105c 85c 25c v sy = 5v i b+ and i b? figure 17. input bias current vs. common-mode voltage and temperature 10k 1k 100 10 1 0.1 0.01 0.001 0.01 0.1 load current (ma) 11 01 output voltage (v oh ) to supply rail (mv) 07416-018 0 0 v sy = 5v ?40c +25c +85c +125c figure 18. output voltage (v oh ) to supply rail vs. load current and temperature
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 8 of 24 t a = 25c, unless otherwise noted. 10k 1k 100 10 1 0.1 0.01 0.001 0.01 0.1 load current (ma) 1 10 100 output voltage (v ol ) to supply rail (mv) 07416-019 v sy = 1.8v ?40c +25c +85c +125c figure 19. output voltage (v ol ) to supply rail vs. load current and temperature 1.800 1.795 1.790 1.785 1.780 1.775 ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 temperature (c) output voltage [v oh ] (v) 07416-021 v sy = 1.8v r l = 100k ? r l = 10k ? figure 20. output voltage (v oh ) vs. temperature 25 20 15 10 5 0 ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 temperature (c) output voltage [v ol ] (mv) 07416-023 v sy = 1.8v r l = 100k ? r l = 10k ? figure 21. output voltage (v ol ) vs. temperature 10k 1k 100 10 1 0.1 0.01 0.001 0.01 0.1 load current (ma) 1 10 100 output voltage (v ol ) to supply rail (mv) 07416-020 v sy = 5v ?40c +25c +85c +125c figure 22. output voltage (v ol ) to supply rail vs. load current and temperature 5.000 4.995 4.990 4.985 4.980 4.975 4.970 ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 temperature (c) output voltage [v oh ] (v) 07416-022 v sy = 5v r l = 100k ? r l = 10k ? figure 23. output voltage (v oh ) vs. temperature 25 20 15 10 5 0 ?40?25?105 203550658095110125 temperature (c) output voltage [v ol ] (mv) 07416-024 v sy = 5v r l = 100k ? r l = 10k ? figure 24. output voltage (v ol ) vs. temperature
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 9 of 24 t a = 25c, unless otherwise noted. 100 80 60 40 20 0 ?20 ?40 ?60 ?80 ?100 225 180 135 90 45 0 ?45 ?90 ?135 ?180 ?225 100 1k 10k 100k 1m frequency (hz) open-loop gain (db) phase (degrees) 07416-025 v sy = 1.8v phase gain figure 25. open-loop gain and phase vs. frequency 60 50 40 30 20 10 0 ?10 ?20 ?30 ?40 ?50 ?60 100 1k 10k 100k 1m frequency (hz) closed-loop gain (db) 07416-027 v sy = 1.8v g = ?1 g = ?10 g = ?100 figure 26. closed-loop gain vs. frequency 10k 1k 100 10 1 0.1 10 100 1k 10k 100k 1m frequency (hz) z out ( ? ) 07416-062 v sy = 1.8v g = ?10 g = ?100 g = ?1 figure 27. output im pedance vs. frequency 100 80 60 40 20 0 ?20 ?40 ?60 ?80 ?100 100 1k 10k 100k 1m frequency (hz) open-loop gain (db) v sy = 5v 225 180 135 90 45 0 ?45 ?90 ?135 ?180 ?225 phase (degrees) 07416-026 phase gain figure 28. open-loop gain and phase vs. frequency 60 50 40 30 20 10 0 ?10 ?20 ?30 ?40 ?50 ?60 100 1k 10k 100k 1m frequency (hz) closed-loop gain (db) 07416-028 v sy = 5v g = ?1 g = ?10 g = ?100 figure 29. closed-loop gain vs. frequency 10k 1k 100 10 1 0.1 10 100 1k 10k 100k 1m frequency (hz) z out ( ? ) 07416-063 v sy = 5v g = ?1 g = ?10 g = ?100 figure 30. output im pedance vs. frequency
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 10 of 24 t a = 25c, unless otherwise noted. 120 100 80 60 40 20 0 100 1k 10k 100k 1m frequency (hz) cmrr (db) 07416-031 v sy = 1.8v figure 31. cmrr vs. frequency 120 100 80 60 40 20 0 10 100 1k 10k 100k 1m frequency (hz) psrr (db) 07416-033 v sy = 1.8v psrr+ psrr? figure 32. psrr vs. frequency 140 130 120 110 100 90 80 ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 temperature (c) psrr (db) 07416-035 1.8v v sy 5v figure 33. psrr vs. temperature 120 100 80 60 40 20 0 100 1k 10k 100k 1m frequency (hz) cmrr (db) 07416-032 v sy = 5v figure 34. cmrr vs. frequency 120 100 80 60 40 20 0 10 100 1k 10k 100k 1m frequency (hz) psrr (db) 07416-034 v sy = 5v psrr+ psrr? figure 35. psrr vs. frequency 1k 100 10 1 10 100 1000 frequency (hz) e n (nv/ hz) 07416-050 v sy = 1.8v v sy = 5v figure 36. voltage noise density vs. frequency
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 11 of 24 t a = 25c, unless otherwise noted. 80 70 60 50 40 30 20 10 0 10 100 1000 capacitance (pf) overshoot (%) 07416-036 v sy = 1.8v v in = 10mv p-p r l = 100k ? os+ os? figure 37. small signal overshoot vs. load capacitance 07416-038 t voltage (500mv/div) time (200s/div) load = 100k ? || 100pf v sy = 1.8v 1.490v p-p figure 38. large signal transient response 07416-040 t vol t age (2mv/div) time (200s/div) load = 100k ? || 100pf v sy = 1.8v figure 39. small signal transient response 80 70 60 50 40 30 20 10 0 10 100 1000 capacitance (pf) overshoot (%) 07416-037 v sy = 5v v in = 10mv p-p r l = 100k ? os+ os? figure 40. small signal overshoot vs. load capacitance 07416-039 t voltage (1v/div) time (200s/div) load = 100k ? || 100pf v sy = 5v 3.959v p-p figure 41. large signal transient response 07416-041 t voltage (2mv/div) time (200s/div) load = 100k ? || 100pf v sy = 5v figure 42. small signal transient response
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 12 of 24 t a = 25c, unless otherwise noted. 07416-064 0 5 10 15 20 25 30 35 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 i sy ( a) v sy (v) ada4505-4 ada4505-2 ADA4505-1 figure 43. supply current vs. supply voltage 07416-052 input voltage noise (0.5v/div) time (s) v sy = 1.8v 2.95v p-p figure 44. input voltage noise, 0.1 hz to 10 hz noise 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 100 1k 10k 100k frequency (hz) channel separation (db) 07416-057 v sy = 1.8v r l = 100k ? g = ?100 v in = 0.5v p-p v in = 1v p-p v in = 1.7v p-p 100k ? 1k? figure 45. channel separation vs. frequency 07416-065 0 5 10 15 20 25 30 40 35 i sy ( a) ?40 ?25 ?10 5 20 35 50 65 80 95 110 125 ADA4505-1, v sy = 1.8v ada4505-2, v sy = 1.8v ADA4505-1, v sy = 5v ada4505-4, v sy = 5v temperature (c) ada4505-4, v sy = 1.8v ada4505-2, v sy = 5v figure 46. total supply current vs. temperature 07416-053 input voltage noise (0.5v/div) time (s) v sy = 5v 2.95v p-p figure 47. input voltage noise, 0.1 hz to 10 hz noise 0 ?20 ?40 ?60 ?80 ?100 ?120 ?140 100 1k 10k 100k frequency (hz) channel separation (db) 07416-058 v sy = 5v r l = 100k ? g = ?100 v in = 1v p-p v in = 2v p-p v in = 3v p-p v in = 4v p-p v in = 4.99v p-p 100k ? 1k ? figure 48. channel separation vs. frequency
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 13 of 24 t a = 25c, unless otherwise noted. 1.8 1.5 1.2 0.9 0.6 0.3 0 10 100 1k 10k 100k frequency (hz) output swing (v) 07416-059 v sy = 1.8v v in = 1.7v g = 1 r l = 100k ? figure 49. output swing vs. frequency 07416-066 v sy = 0.9v g = 1 r l = 100k ? c l = no load v in v out time (400s/div) figure 50. no phase reversal 6 5 4 3 2 1 0 10 100 1k 10k 100k frequency (hz) output swing (v) 07416-060 v sy = 5v v in = 4.9v g = 1 r l = 100k ? figure 51. output swing vs. frequency 07416-067 1 2 time (400s/div) v out v sy = 2.5v g = 1 r l = 100k ? c l = no load v in figure 52. no phase reversal
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 14 of 24 theory of operation the ADA4505-1/ada4505-2/ada4505-4 are unity-gain stable cmos rail-to-rail input/output operational amplifiers designed to optimize performance in current consumption, psrr, cmrr, and zero crossover distortion, all embedded in a small package. the typical offset voltage is 500 v, with a low peak-to-peak voltage noise of 2.95 v from 0.1 hz to 10 hz and a voltage noise density of 65 nv/hz at 1 khz. the ada4505-x amplifiers are designed to solve two key problems in low voltage battery-powered applications: battery voltage decrease over time and rail-to-rail input stage distortion. in battery-powered applications, the supply voltage available to the ic is the voltage of the battery. unfortunately, the voltage of a battery decreases as it discharges itself through the load. this voltage drop over the lifetime of the battery causes an error in the output of the op amps. some applications requiring precision measurements during the entire lifetime of the battery use voltage regulators to power up the op amps as a solution. if a design uses standard battery cells, the op amps experience a supply voltage change from roughly 3.2 v to 1.8 v during the lifetime of the battery. this means that for a psrr of 70 db minimum in a typical op amp, the input-referred offset error is approximately 440 v. if the same application uses the ada4505-x with a 100 db minimum psrr, the error is only 14 v. it is possible to calibrate this error out or to use an external voltage regulator to power the op amp, but these solutions can increase system cost and complexity. the ada4505-x amplifiers solve the impasse with no additional cost or error-nullifying circuitry. the second problem with battery-powered applications is the distortion caused by the standard rail-to-rail input stage. using a cmos nonrail-to-rail input stage (that is, a single differential pair) limits the input voltage to approximately one v gs (gate- source voltage) away from one of the supply lines. because v gs for normal operation is commonly over 1 v, a single differential pair, input stage op amp greatly restricts the allowable input voltage range when using a low supply voltage. this limitation restricts the number of applications where the nonrail-to-rail input op amp was originally intended to be used. to solve this problem, a dual differential pair input stage is usually implemented (see figure 53 ); however, this technique has its own drawbacks. one differential pair amplifies the input signal when the common- mode voltage is on the high end, whereas the other pair amplifies the input signal when the common-mode voltage is on the low end. this method also requires control circuitry to operate the two differential pairs appropriately. unfortunately, this topology leads to a very noticeable and undesirable problem; if the signal level moves through the range where one input stage turns off and the other one turns on, noticeable distortion occurs (see figure 54 ). 07416-043 i b i b v in? v in+ v ss v dd q2 q3 q1 q4 v bias figure 53. typical dual differential pair input stage op amp (dual pmos q1 and q2 transistors form the lower end of the input voltage range; dual nmos q3 and q4 tr ansistors form the upper end) v cm (v) v os (v) 0 ?300 ?100 100 300 1.5 3.5 5.0 1.0 0.5 2.5 4.54.0 3.0 2.0 ?200 ?150 ?250 ?50 0 50 150 200 250 07416-044 v sy = 5v t a = 25c figure 54. typical input offset voltage vs. common-mode voltage response in a dual differential pair input stage op amp (powered by a 5 v supply; results of approximately 1 00 units per graph are displayed) this distortion forces the designer to devise impractical ways to avoid the crossover distortion areas, thereby narrowing the common-mode dynamic range of the operational amplifier. the ada4505-x family solves this crossover distortion problem by using an on-chip charge pump to power the input differential pair. the charge pump creates a supply voltage higher than the voltage of the battery, allowing the input stage to handle a wide range of input signal voltages without using a second differential pair. with this solution, the input voltage can vary from one supply extreme to the other with no distortion, thereby restoring the full common-mode dynamic range of the op amp. the charge pump has been carefully designed so that switching noise components at any frequency, both within and beyond the amplifier bandwidth, are much lower than the thermal noise floor. therefore, the spurious-free dynamic range (sfdr) is limited only by the input signal and the thermal or flicker noise. there is no intermodulation between input signal and switching noise.
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 15 of 24 figure 55 displays a typical front-end section of an operational amplifier with an on-chip charge pump. 07416-045 q2 q1 v pp v bias +in ?in out cascode stage and rail-to-rail output stage v dd v ss v pp = positive pumped voltage = v dd + 1.8 v figure 55. typical front-end section of an op amp with embedded charge pump figure 56 shows the typical response of two devices from figure 12 , which shows the input offset voltage vs. input common-mode voltage for 10 devices. figure 56 is expanded to make it easier to compare with figure 54 , which shows the typical input offset voltage vs. common-mode voltage response in a dual differential pair input stage op amp. v cm (v) v os (v) 0 ?300 ?100 100 300 1.5 3.5 5.0 1.00.5 2.5 4.54.0 3.0 2.0 ?200 ?150 ?250 ?50 0 50 150 200 250 07416-046 v sy = 5v t a = 25c figure 56. input offset voltage vs. input common-mode voltage response (powered by a 5 v supply; results of two units are displayed) this solution improves the cmrr performance tremendously. for example, if the input varies from rail to rail on a 2.5 v supply rail, using a part with a cmrr of 70 db minimum, an input-referred error of 790 v is introduced. another part with a cmrr of 52 db minimum generates a 6.3 mv error. the ada4505-x family cmrr of 90 db minimum causes only a 79 v error. as with the psrr error, there are complex ways to minimize this error, but the ada4505-x family solves this problem without incurring unnecessary circuitry complexity or increased cost.
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 16 of 24 applications information pulse oximeter current source a pulse oximeter is a noninvasive medical device used for continuously measuring the percentage of hemoglobin (hb) saturated with oxygen and the pulse rate of a patient. hemo- globin that is carrying oxygen (oxyhemoglobin) absorbs light in the infrared (ir) region of the spectrum; hemoglobin that is not carrying oxygen (deoxyhemoglobin) absorbs visible red (r) light. in pulse oximetry, a clip containing two leds (sometimes more, depending on the complexity of the measurement algorithm) and the light sensor (photodiode) is placed on the finger or earlobe of the patient. one led emits red light (600 nm to 700 nm), and the other emits light in the near ir (800 nm to 900 nm) region. the clip is connected by a cable to a processor unit. the leds are rapidly and sequentially excited by two current sources (one for each led) whose dc levels depend on the led being driven, based on manufacturer requirements; the detector is synchronized to capture the light from each led as it is transmitted through the tissue. an example design of a dc current source driving the red and infrared leds is shown in figure 57 . these dc current sources allow 62.5 ma and 101 ma to flow through the red and infrared leds, respectively. first, to prolong battery life, the leds are driven only when needed. one third of the adg733 spdt analog switch is used to disconnect/connect the 1.25 v voltage reference from/to each current circuit. when driving the leds, the adr1581 1.25 v voltage reference is buffered by one half of the ada4505-2; the presence of this voltage on the noninverting input forces the output of the op amp (due to the negative feed- back) to maintain a level that causes its inverting input to track the noninverting pin. therefore, the 1.25 v appears in parallel with the 20 r1 or 12.4 r5 current source resistor, creating the flow of the 62.5 ma or 101 ma current through the red or infrared led as the output of the op amp turns on the q1 or q2 n-mosfet irlms2002. the maximum total quiescent currents for one half of the ada4505-2, the adr1581 , and the adg733 are 15 a, 70 a, and 1 a, respectively, for a total of 86 a current consumption (430 w power consumption) per circuit, which is good for a system powered by a battery. if the accuracy and temperature drift of the total design need improvement, use a more accurate and low temperature coefficient drift voltage reference and current source resistor. c3 and c4 are used to improve stabilization of u1; r3 and r7 are used to provide some current limit into the u1 inverting pin; and r2 and r6 are used to slow the rise time of the n-mosfet when it turns on. these elements may not be needed, or some bench adjustments may be required. 07416-047 8 4 6 7 5 c1 0.1f +5v c3 22pf r2 22? r3 1k? v out1 u1 1/2 ada4505-2 62.5ma connect to red led r1 20? 0.1% 1/4 w min red current source 8 4 2 1 3 +5v c4 22pf r6 22 ? r7 1k? v out2 101ma connect to infrared led r5 12.4 ? 0.1% 1/2 w min infrared current source q2 irlms2002 q1 irlms2002 s1a s1b d1 s2a s2b d2 s3a s3b d3 gnd a2 a1 a0 en v ss v dd i_bit2 i_bit1 i_bit0 i_ena r4 53.6k ? u3 adr1581 c2 0.1f +5 v u2 adg733 v ref = 1.25v +5v 14 15 4 16 8 12 13 2 1 5 3 9 10 11 6 7 v+ v? u1 1/2 ada4505-2 v+ v? figure 57. pulse oximeter red and infrared current sources using the ada4505-2 as a buffer to the voltage reference device
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 17 of 24 four-pole, low-pass butterworth filter for glucose monitor there are several methods of glucose monitoring: spectroscopic absorption of infrared light in the 2 m to 2.5 m range, reflec- tance spectrophotometry, and the amperometric type using electrochemical strips with glucose oxidase enzymes. the amperometric type generally uses three electrodes: a reference electrode, a control electrode, and a working electrode. although this is a very old and widely used technique, signal-to-noise ratio and repeatability can be improved using the ada4505-x family, with its low peak-to-peak voltage noise of 2.95 v from 0.1 hz to 10 hz and voltage noise density of 65 nv/hz at 1 khz. another consideration is operation from a 3.3 v battery. glucose signal currents are usually less than 3 a full scale; therefore, the i-to-v converter requires low input bias current. the ada4505-x family is an excellent choice because it provides 0.5 pa typical and 2 pa maximum input bias current at ambient temperature. a low-pass filter with a cutoff frequency of 80 hz to 100 hz is desirable in a glucose meter device to remove extraneous noise; this can be a simple two-pole or four-pole butterworth filter. low power op amps with bandwidths of 50 khz to 500 khz should be adequate. the ada4505-x family, with its 50 khz gbp and 7 a typical current consumption, meets these requirements. a circuit design of a four-pole butterworth filter (preceded by a one-pole low-pass filter) is shown in figure 58 . with a 3.3 v battery, the total power consumption of this design is 198 w typical at ambient temperature. 07416-048 8 4 2 1 3 +3.3v v out c4 0.1f c5 0.047f r5 22.6k ? r4 22.6k ? 8 4 6 7 5 r2 22.6k ? +3.3v c2 0.1f c3 0.047f r3 22.6k ? 8 4 2 1 3 +3.3v duplicate of circuit above control working reference r1 5m ? c1 1000pf u2 1/2 ada4505-2 u1 1/2 ada4505-2 u1 1/2 ada4505-2 v+ v? v+ v? v+ v? figure 58. four-pole butterworth filter that can be used in a glucose meter
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 18 of 24 outline dimensions compliant to jedec standards mo-178-aa 121608-a 10 5 0 seating plane 1.90 bsc 0.95 bsc 0.20 bsc 5 123 4 3.00 2.90 2.80 3.00 2.80 2.60 1.70 1.60 1.50 1.30 1.15 0.90 0 .15 max 0 .05 min 1.45 max 0.95 min 0.20 max 0.08 min 0.50 max 0.35 min 0.55 0.45 0.35 figure 59. 5-lead small outline transistor package [sot-23] (rj-5) dimensions shown in millimeters 081709-a 0.40 bsc 0.80 bsc 1.425 1.385 1.345 0.945 0.905 0.865 seating plane 0.645 0.600 0.555 0.415 0.400 0.385 0.40 bsc a 12 b c top view (ball side down) bottom view (ball side up) ball a1 identifier 0.05 nom coplanarity 0.230 0.200 0.170 0.287 0.267 0.247 figure 60. 6-ball wafer level chip scale package [wlcsp] (cb-6-7) dimensions shown in millimeters
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 19 of 24 011008-b seating plane 0.50 ball pitch 1.460 1.420 sq 1.380 0.270 0.240 0.210 0.380 0.355 0.330 0.340 0.320 0.300 0.650 0.595 0.540 bottom view (ball side up) top view a 123 b c ball 1 identifier coplanarity 0.075 figure 61. 8-ball wafer level chip scale package [wlcsp] (cb-8-2) dimensions shown in millimeters compliant to jedec standards mo-187-aa 100709-b 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 figure 62. 8-lead mini small outline package [msop] (rm-8) dimensions shown in millimeters
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 20 of 24 compliant to jedec standards mo-153-ab-1 061908-a 8 0 4.50 4.40 4.30 14 8 7 1 6.40 bsc pin 1 5.10 5.00 4.90 0.65 bsc 0.15 0.05 0.30 0.19 1.20 max 1.05 1.00 0.80 0.20 0.09 0.75 0.60 0.45 coplanarity 0.10 seating plane figure 63. 14-lead thin shrink small outline package [tssop] (ru-14) dimensions shown in millimeters 061208-a a b c d e 0.650 0.595 0.540 1.50 1.46 1.42 3.00 2.96 2.92 1 2 3 bottom view (ball side up) top view (ball side down) 0.340 0.320 0.300 2.00 bsc ball 1 identifier seating plane 1.00 bsc 0.50 bsc 0.50 bsc 0.25 bsc 0.25 bsc 0.25 bsc 0.25 bsc 0.50 bsc 0.50 bsc 0.380 0.355 0.330 0.270 0.240 0.210 0.10 max coplanarity figure 64. 14-ball wafer level chip scale package [wlcsp] (cb-14-1) dimensions shown in millimeters
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 21 of 24 ordering guide model 1 temperature range package description package option branding ADA4505-1arjz-r2 ?40c to +125c 5-lead sot-23 rj-5 a2d ADA4505-1arjz-rl ?40c to +125c 5-lead sot-23 rj-5 a2d ADA4505-1arjz-r7 ?40c to +125c 5-lead sot-23 rj-5 a2d ADA4505-1acbz-r7 ?40c to +125c 6-ball wlcsp cb-6-7 a2f ADA4505-1acbz-rl ?40c to +125c 6-ball wlcsp cb-6-7 a2f ada4505-2acbz-rl ?40c to +125c 8-ball wlcsp cb-8-2 a21 ada4505-2acbz-r7 ?40c to +125c 8-ball wlcsp cb-8-2 a21 ada4505-2armz ?40c to +125c 8-lead msop rm-8 a21 ada4505-2armz-rl ?40c to +125c 8-lead msop rm-8 a21 ada4505-4aruz ?40c to +125c 14-lead tssop ru-14 ada4505-4aruz-rl ?40c to +125c 14-lead tssop ru-14 ada4505-4acbz-rl ?40c to +125c 14-ball wlcsp cb-14-1 a2a ada4505-4acbz-r7 ?40c to +125c 14-ball wlcsp cb-14-1 a2a 1 z = rohs compliant part.
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 22 of 24 notes
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 23 of 24 notes
ADA4505-1/ada4505-2/ada4505-4 rev. d | page 24 of 24 notes ?2008C2010 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d07416-0-7/1 0(d)

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