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micropower, low noise precision voltage references with shutdown adr390/ADR391/adr392/adr395 rev. f 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 ri ghts of analog devices. trademarks and registered trademarks are the prop erty 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 ? 2005 analog devices, inc. all rights reserved. features compact tsot-23-5 packages low temperature coefficient b grade: 9 ppm/c a grade: 25 ppm/c initial accuracy b grade: 4 mv maximum a grade: 6 mv maximum ultralow output noise: 5 v p-p (0.1 hz to 10 hz) low dropout: 300 mv low supply current 3 a maximum in shutdown 120 a maximum in operation no external capacitor required output current: 5 ma wide temperature range ?40c to + 125c applications battery-powered instrumentation portable medical instrumentation data acquisition systems industrial process controls automotive functional block diagram 1 2 3 adr390/ ADR391/ adr392/ adr395 5 4 shdn v in v out (sense) gnd v out (force) (not to scale) 00419-d-001 figure 1. 5-lead tsot (uj suffix) table 1. model v out (v) temperature coefficient (ppm/c) accuracy (mv) adr390b 2.048 9 4 adr390a 2.048 25 6 ADR391b 2.5 9 4 ADR391a 2.5 25 6 adr392b 4.096 9 5 adr392a 4.096 25 6 adr395b 5.0 9 5 adr395a 5.0 25 6 general description the adr390, ADR391, adr392, and adr395 are precision 2.048 v, 2.5 v, 4.096 v, and 5 v band gap voltage references, respectively, featuring low power and high precision in a tiny footprint. using adis patented temperature drift curvature correction techniques, the adr39x references achieve a low 9 ppm/c of temperature drift in the tsot package. the adr39x family of micropower, low dropout voltage references provides a stable output voltage from a minimum supply of 300 mv above the output. their advanced design eliminates the need for external capacitors, which further reduces board space and system cost. the combination of low power operation, small size, and ease of use makes the adr39x precision voltage references ideally suited for battery- operated applications.
adr390/ADR391/adr392/adr395 rev. f | page 2 of 20 table of contents adr390 specifications .................................................................... 3 ADR391 specifications .................................................................... 4 adr392 specifications .................................................................... 5 adr395 specifications .................................................................... 6 absolute maximum ratings............................................................ 7 thermal resistance ...................................................................... 7 esd caution.................................................................................. 7 terminology .......................................................................................8 typical performance characteristics ..............................................9 theory of operation ...................................................................... 16 applications..................................................................................... 17 basic voltage reference connection ....................................... 17 outline dimensions ....................................................................... 19 ordering guide .......................................................................... 19 revision history 5/05rev. e to rev. f changes to table 5........................................................................... 7 changes to figure 2......................................................................... 9 4/04rev. d to rev. e changes to adr390specifications............................................ 3 changes to ADR391specifications............................................ 4 changes to adr392specifications............................................ 5 changes to adr395specifications............................................ 6 4/04rev. c to rev. d updated format................................................................ universal changes to title ............................................................................... 1 changes to features......................................................................... 1 changes to applications ................................................................. 1 changes to general description ................................................... 1 changes to table 1........................................................................... 1 changes to adr390specifications............................................ 3 changes to ADR391specifications............................................ 4 changes to adr392specifications............................................ 5 changes to adr395specifications............................................ 6 changes to absolute maximum ratings ...................................... 7 changes to thermal resistance..................................................... 7 moved esd caution........................................................................ 7 changes to figure 3, figure 4, figure 7, and figure 8 ................ 9 changes to figure 11, figure 12, figure 13, and figure 14...... 10 changes to figure 15, figure 16, figure 19, and figure 20...... 11 changes to figure 23 and figure 24............................................ 12 changes to figure 27..................................................................... 13 changes to ordering guide ......................................................... 19 updated outline dimensions...................................................... 19 10/02rev. b to rev. c add parts adr392 and adr395 ....................................universal changes to features ........................................................................ 1 changes to general description ................................................... 1 additions to table i......................................................................... 1 changes to specifications............................................................... 2 changes to ordering guide ........................................................... 4 changes to absolute maximum ratings...................................... 4 new tpcs 3, 4, 7, 8, 11, 12, 15, 16, 19, and 20 ............................ 6 new figures 4 and 5...................................................................... 13 deleted a negative precision reference without precision resistors section ............................................ 13 edits to general-purpose current source section ................... 13 updated outline dimensions...................................................... 15 5/02rev. a to rev. b edits to layout ...................................................................universal changes to figure 6....................................................................... 13 revision 0: initial version
adr390/ADR391/adr392/adr395 rev. f | page 3 of 20 adr390 specifications electrical characteristics, v in = 2.5 v to 15 v, t a = 25c, unless otherwise noted. table 2. parameter symbol conditions min typ max unit output voltage v o a grade 2.042 2.048 2.054 v v o b grade 2.044 2.048 2.052 v initial accuracy v oerr a grade 6 mv v oerr a grade 0.29 % v oerr b grade 4 mv v oerr b grade 0.19 % a grade: ?40c < t a < +125c 25 ppm/c temperature coefficient tcv o b grade: ?40c < t a < +125c 9 ppm/c supply voltage headroom v in ? v o 300 mv line regulation ?v o /?v in v in = 2.5 v to 15 v, ?40c < t a < +125c 10 25 ppm/v i load = 0 ma to 5 ma, ?40c < t a < +85c, v in = 3 v 60 ppm/ma load regulation ?v o /?i load i load = 0 ma to 5 ma, ?40c < t a < +125c, v in = 3 v 140 ppm/ma no load 120 a quiescent current i in ?40c < t a < +125c 140 a voltage noise en p-p 0.1 hz to 10 hz 5 v p-p turn-on settling time t r 20 s long-term stability 1 ?v o 1000 hours 50 ppm output voltage hysteresis ?v o_hys 100 ppm ripple rejection ratio rrr f in = 60 khz 80 db v in = 5 v 25 ma short circuit to gnd i sc v in = 15 v 30 ma shutdown pin shutdown supply current i shdn 3 a shutdown logic input current i logic 500 na shutdown logic low v inl 0.8 v shutdown logic high v inh 2.4 v 1 the long-term stability specification is noncumulative. the drift of subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
adr390/ADR391/adr392/adr395 rev. f | page 4 of 20 ADR391 specifications electrical characteristics, v in = 2.8 v to 15 v, t a = 25c, unless otherwise noted. table 3. parameter symbol conditions min typ max unit output voltage v o a grade 2.494 2.5 2.506 v v o b grade 2.496 2.5 2.504 v v oerr a grade 6 mv initial accuracy v oerr a grade 0.24 % v oerr b grade 4 mv v oerr b grade 0.16 % a grade, ?40c < t a < +125c 25 ppm/c temperature coefficient tcv o b grade, ?40c < t a < +125c 9 ppm/c supply voltage headroom v in ? v o 300 mv line regulation ?v o /?v in v in = 2.8 v to 15 v, ?40c < t a < +125c 10 25 ppm/v i load = 0 ma to 5 ma, ?40c < t a < +85c, v in = 3 v 60 ppm/ma load regulation ?v o /?i load i load = 0 ma to 5 ma, ?40c < t a < +125c, v in = 3 v 140 ppm/ma no load 120 a quiescent current i in ?40c < t a < +125c 140 a voltage noise en p-p 0.1 hz to 10 hz 5 v p-p turn-on settling time t r 20 s long-term stability 1 ?v o 1000 hours 50 ppm output voltage hysteresis ?v o_hys 100 ppm ripple rejection ratio rrr f in = 60 khz 80 db v in = 5 v 25 ma short circuit to gnd i sc v in = 15 v 30 ma shutdown pin shutdown supply current i shdn 3 a shutdown logic input current i logic 500 na shutdown logic low v inl 0.8 v shutdown logic high v inh 2.4 v 1 the long-term stability specification is noncumulative. the drift of subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
adr390/ADR391/adr392/adr395 rev. f | page 5 of 20 adr392 specifications electrical characteristics, v in = 4.3 v to 15 v, t a = 25c, unless otherwise noted. table 4. parameter symbol conditions min typ max unit output voltage v o a grade 4.090 4.096 4.102 v v o b grade 4.091 4.096 4.101 v v oerr a grade 6 mv initial accuracy v oerr a grade 0.15 % v oerr b grade 5 mv v oerr b grade 0.12 % a grade, ?40c < t a < +125c 25 ppm/c temperature coefficient tcv o b grade, ?40c < t a < +125c 9 ppm/c supply voltage headroom v in ? v o 300 mv line regulation ?v o /?v in v in = 4.3 v to 15 v, ?40c < t a < +125c 10 25 ppm/v load regulation ?v o /?i load i load = 0 ma to 5 ma, ?40c < t a < +125c, v in = 5 v 140 ppm/ma no load 120 a quiescent current i in ?40c < t a < +125c 140 a voltage noise en p-p 0.1 hz to 10 hz 7 v p-p turn-on settling time t r 20 s long-term stability 1 ?v o 1000 hours 50 ppm output voltage hysteresis ?v o_hys 100 ppm ripple rejection ratio rrr f in = 60 khz 80 db v in = 5 v 25 ma short circuit to gnd i sc v in = 15 v 30 ma shutdown pin shutdown supply current i shdn 3 a shutdown logic input current i logic 500 na shutdown logic low v inl 0.8 v shutdown logic high v inh 2.4 v 1 the long-term stability specification is noncumulative. the drift of subsequent 1000 hour periods is significantly lower than in the first 1000 hour period.
adr390/ADR391/adr392/adr395 rev. f | page 6 of 20 adr395 specifications electrical characteristics, v in = 5.3 v to 15 v, t a = 25c, unless otherwise noted. table 5. parameter symbol conditions min typ max unit output voltage v o a grade 4.994 5.000 5.006 v v o b grade 4.995 5.000 5.005 v v oerr a grade 6 mv initial accuracy v oerr b grade 0.12 % v oerr b grade 5 mv v oerr b grade 0.10 % a grade, ?40c < t a < +125c 25 ppm/c temperature coefficient tcv o b grade, ?40c < t a < +125c 9 ppm/c supply voltage headroom v in ? v o 300 mv line regulation ?v o /?v in v in = 4.3 v to 15 v, ?40c < t a < +125c 10 25 ppm/v load regulation ?v o /?i load i load = 0 ma to 5 ma, ?40c < t a < +125c, v in = 6 v 140 ppm/ma no load 120 a quiescent current i in ?40c < t a < +125c 140 a voltage noise en p-p 0.1 hz to 10 hz 8 v p-p turn-on settling time t r 20 s long-term stability 1 ?v o 1, 000 hours 50 ppm output voltage hysteresis ?v o_hys 100 ppm ripple rejection ratio rrr f in = 60 khz 80 db v in = 5 v 25 ma short circuit to gnd i sc v in = 15 v 30 ma shutdown pin shutdown supply current i shdn 3 a shutdown logic input current i logic 500 na shutdown logic low v inl 0.8 v shutdown logic high v inh 2.4 v 1 the long-term stability specif ication is noncumulative. the drift of subsequent 1, 000 hour periods is sign ificantly lower than in the first 1,000 hour period.
adr390/ADR391/adr392/adr395 rev. f | page 7 of 20 absolute maximum ratings at 25c, unless otherwise noted. table 6. parameter rating supply voltage 18 v output short-circuit duration to gnd see derating curves storage temperature range C65c to +125c operating temperature range C40c to +125c junction temperature range C65c to +125c lead temperature range (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 and 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, ja is specified for a device soldered in a circuit board for surface- mount packages. table 7. thermal resistance package type ja jc unit tsot-23-5 (uj-5) 230 146 c/w esd caution esd (electrostatic discharge) sensitive device. electrosta tic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without de tection. although th is product features proprietary esd protection circuitry, permanent dama ge may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality.
adr390/ADR391/adr392/adr395 rev. f | page 8 of 20 terminology temperature coefficient the change of output voltage with respect to operating temp- erature changes normalized by the output voltage at 25c. this parameter is expressed in ppm/c and can be determined by the following equation: [] () () () () 6 10 C 25 C = 1 2 o 1 o 2 o o t t c v t v t v c / ppm tcv where: v o (25c) = v o at 25c v o ( t 1 ) = v o at temperature 1 v o ( t 2 ) = v o at temperature 2 line regulation the change in output voltage due to a specified change in input voltage. this parameter accounts for the effects of self-heating. line regulation is expressed in either percent per volt, parts- per-million per volt, or microvolts per volt change in input voltage. load regulation the change in output voltage due to a specified change in load current. this parameter accounts for the effects of self-heating. load regulation is expressed in either microvolts per milli- ampere, parts-per-million per milliampere, or ohms of dc output resistance. long-term stability typical shift of output voltage at 25c on a sample of parts subjected to a test of 1,000 hours at 25c. ? v o = v o ( t 0 ) C v o ( t 1 ) [] () () () ? ? ? ? ? ? ? ? = ? 6 10 C 0 o 1 o 0 o o t v t v t v ppm v where: v o ( t 0 ) = v o at 25c at time 0 v o ( t 1 ) = v o at 25c after 1,000 hours operation at 25c thermal hysteresis the change of output voltage after the device is cycled through temperatures from +25c to C40c to +125c and back to +25c. this is a typical value from a sample of parts put through such a cycle. v o_hys = v o (25c) C v o_tc [] ( ) () 6 10 25 C 25 = c v v c v ppm v o o_tc o o_hys where: v o (25c) = v o at 25c v o_tc = v o at 25c after a temperature cycle from + 25c to C40c to +125c and back to +25c notes input capacitor input capacitors are not required on the adr39x. there is no limit for the value of the capacitor used on the input, but a 1 f to 10 f capacitor on the input improves transient response in applications where the supply suddenly changes. an additional 0.1 f in parallel also helps reduce noise from the supply. output capacitor the adr39x does not require output capacitors for stability under any load condition. an output capacitor, typically 0.1 f, filters out any low level noise voltage and does not affect the operation of the part. on the other hand, the load transient response can improve with the addition of a 1 f to 10 f output capacitor in parallel. a capacitor here acts as a source of stored energy for a sudden increase in load current. the only parameter that degrades by adding an output capacitor is the turn-on time, and it depends on the size of the capacitor chosen. ?150 drift (ppm) 150 time (hours) 0 ?100 ?50 0 50 100 100 200 300 400 500 600 700 1000 00419-d-002 900 800 figure 2. ADR391 typical long-term drift over 1,000 hours
adr390/ADR391/adr392/adr395 rev. f | page 9 of 20 typical performance characteristics temperature ( c) 2.040 ?40 ?5 output voltage (v) 30 65 100 125 2.044 2.048 2.052 2.056 2.060 sample 3 sample 2 sample 1 00419-d-003 figure 3. adr390 output voltage vs. temperature 2.494 ?40 ?5 v out (v) 30 65 100 125 2.496 2.498 2.500 2.502 2.504 2.506 sample 1 sample 2 sample 3 00419-d-004 temperature ( c) figure 4. ADR391 output voltage vs. temperature temperature ( c) 4.100 ?40 0 40 80 125 v out (v) 4.098 4.096 4.094 4.090 4.088 4.092 sample 1 sample 2 sample 3 00419-d-005 figure 5. adr392 output voltage vs. temperature 5.006 ?40 ?5 30 65 125 v out (v) 5.004 5.002 5.000 4.996 4.994 4.998 100 sample 1 sample 2 sample 3 00419-d-006 temperature ( c) figure 6. adr395 output voltage vs. temperature input voltage (v) 140 120 40 2.5 15.0 5.0 supply current ( a) 7.5 10.0 12.5 100 80 60 +125 c +25 c ?40 c 00419-d-007 +85 c figure 7. adr390 supply current vs. input voltage input voltage (v) 140 120 40 2.5 15.0 5.0 supply current ( a) 7.5 10.0 12.5 100 80 60 +85 c +25 c ?40 c 00419-d-008 figure 8. ADR391 supply current vs. input voltage
adr390/ADR391/adr392/adr395 rev. f | page 10 of 20 input voltage (v) 140 57911 15 supply current ( a) 120 100 60 40 80 13 +125 c +25 c ?40 c 00419-d-009 figure 9. adr392 supply current vs. input voltage input voltage (v) 140 5.5 7.0 8.5 10.0 14.5 supply current ( a) 120 100 60 40 80 13.0 +125 c +25 c ?40 c 11.5 00419-d-010 figure 10. adr395 supply current vs. input voltage temperature ( c) 0 ?40 ?10 load regulation (ppm/ma) 20 50 80 125 20 40 60 80 100 120 00419-d-011 110 v in = 3.0v v in = 5.0v i l = 0ma to 5ma figure 11. adr390 load regulation vs. temperature temperature ( c) 80 ?40 ?10 load regulation (ppm/ma) 50 80 110 125 100 120 140 160 180 00419-d-012 v in = 5.0v v in = 3.0v i l = 0ma to 5ma 20 figure 12. ADR391 load regulation vs. temperature temperature ( c) 90 ?40 ?5 30 65 125 load regulation (ppm/ma) 80 70 50 40 60 v in = 7.5v 100 v in = 5v 00419-d-013 i l = 0ma to 5ma figure 13. adr392 load regulation vs. temperature temperature ( c) 80 ?40 ?5 30 65 125 load regulation (ppm/ma) 70 60 40 30 50 v in = 7.5v 100 v in = 5v 00419-d-014 i l = 0ma to 5ma figure 14. adr395 load regulation vs. temperature
adr390/ADR391/adr392/adr395 rev. f | page 11 of 20 temperature ( c) 0 ? 40 ? 10 line regulation (ppm/v) 20 80 110 125 25 5 10 15 20 00419-d-015 50 figure 15. adr390 line regulation vs. temperature temperature ( c) 0 line regulation (ppm/v) 25 5 10 15 20 00419-d-016 ? 40 ? 10 20 80 110 125 50 figure 16. ADR391 line regulation vs. temperature temperature ( c) 14 ?40?53065 125 line regulation (ppm/v) 10 6 2 0 4 100 12 8 v in = 4.4v to 15v 00419-d-017 figure 17. adr392 line regulation vs. temperature temperature ( c) 14 ?40?53065 125 line regulation (ppm/v) 10 6 2 0 4 100 12 8 v in = 5.3v to 15v 00419-d-018 figure 18. adr395 line regulation vs. temperature load current (ma) 3.0 2.0 01 vin_min (v) 234 2.6 2.4 2.2 ?40 c +85 c +25 c 00419-d-019 5 2.8 +125 c figure 19. adr390 minimum input voltage vs. load current load current (ma) 3.6 2.6 01 3.4 3.2 2.8 ?40 c +85 c +25 c vin_min (v) 00419-d-020 2345 3.0 +125 c figure 20. ADR391 minimum input voltage vs. load current
adr390/ADR391/adr392/adr395 rev. f | page 12 of 20 load current (ma) 4.8 0123 5 vin_min (v) 4.4 4.0 3.8 4.2 4 4.6 +125 c +25 c ?40 c 00419-d-021 figure 21. adr392 minimum input voltage vs. load current load current (ma) 6.0 0123 5 vin_min (v) 5.2 4.8 4.6 5.0 4 5.6 +125 c +25 c ?40 c 5.8 5.4 00419-d-022 figure 22. adr395 minimum input voltage vs. load current v out deviation (mv) 60 50 0 ?0.24 0.30 ?0.12 frequency 0 0.06 0.18 40 30 20 10 ?0.18 ?0.06 0.12 0.24 00419-d-023 temperature: +25 c ?40 c +125 c +25 c figure 23. adr390 v out hysteresis distribution v out deviation (mv) 70 50 0 ?0.56 ?0.26 frequency 0.04 0.19 40 30 20 10 ?0.41 ?0.11 0.34 60 temperature: +25 c ?40 c +125 c +25 c 00419-d-024 figure 24. ADR391 v out hysteresis distribution frequency (hz) 1k 100 10 10k 100 voltage noise density (nv/ hz) 1k adr390 ADR391 v in = 5v 00419-d-025 figure 25. voltage noise density vs. frequency voltage (2 v/div) time (1 sec/div) 0 0 0 0 0 0 0 0 0 00419-d-026 figure 26. ADR391 typical voltage noise 0.1 hz to 10 hz
adr390/ADR391/adr392/adr395 rev. f | page 13 of 20 voltage (100 v/div) time (10 s/div) figure 27. ADR391 voltage noise 10 hz to 10 khz voltage time (10 s/div) c bypass = 0 f line interruption v out 0.5v/div 1v/div 00419-d-028 figure 28. ADR391 line transient response voltage time (10 s/div) c bypass = 0.1 f line interruption v out 0.5v/div 1v/div 00419-d-029 figure 29. ADR391 line transient response voltage (1v/div) time (200 s/div) c l = 0nf v load on v out load off 00419-d-030 figure 30. ADR391 load transient response voltage (1v/div) time (200 s/div) c l = 1nf v out v load on load off 00419-d-031 figure 31. ADR391 load transient response voltage (1v/div) time (200 s/div) c l = 100nf v out v load on load off 00419-d-032 figure 32. ADR391 load transient response
adr390/ADR391/adr392/adr395 rev. f | page 14 of 20 voltage time (20 s/div) v out v in v in = 15v 5v/div 2v/div 00419-d-033 figure 33. ADR391 turn-on response time at 15 v voltage time (40 s/div) v out v in v in = 15v 5v/div 2v/div 00419-d-034 figure 34. ADR391 turn-off response at 15 v voltage time (200 s/div) c bypass = 0.1 f v in v out 5v/div 2v/div 00419-d-035 figure 35. ADR391 turn-on/turn-off response at 5 v voltage time (200 s/div) r l = 500 ? v out v in 5v/div 2v/div 00419-d-036 figure 36. ADR391 turn-on/turn-off response at 5 v voltage (5v/div) time (200 s/div) r l = 500 ? c l = 100nf v out v in 5v/div 2v/div 00419-d-037 figure 37. ADR391 turn-on/turn-off response at 5 v frequency (hz) 10 1m 100 ripple rejection (db) 1k 10k 100k 80 60 ?120 40 20 0 ?20 ?40 ?60 ?80 ?100 00419-d-038 figure 38. ripple rejection vs. frequency
adr390/ADR391/adr392/adr395 rev. f | page 15 of 20 frequency (hz) 10 1m 100 output impedance ( ? ) 1k 10k 100k 100 90 0 80 70 60 50 40 30 20 10 c l = 0 f c l = 0.1 f c l = 1 f 00419-d-039 figure 39. output impedance vs. frequency
adr390/ADR391/adr392/adr395 rev. f | page 16 of 20 theory of operation band gap references are the high performance solution for low supply voltage and low power voltage reference applications, and the adr390/ADR391/adr392/adr395 are no exception. the uniqueness of these devices lies in the architecture. as shown in figure 40, the ideal zero tc band gap voltage is referenced to the output, not to ground. therefore, if noise exists on the ground line, it is greatly attenuated on v out . the band gap cell consists of the pnp pair, q51 and q52, running at unequal current densities. the difference in v be results in a voltage with a positive tc, which is amplified by a ratio of r54 r58 2 this ptat voltage, combined with v be s of q51 and q52, produces a stable band gap voltage. reduction in the band gap curvature is performed by the ratio of the resistors r44 and r59, one of which is linearly temperature dependent. precision laser trimming and other patented circuit techniques are used to further enhance the drift performance. shdn r60 q51 r54 r61 r53 q52 r58 r59 r44 r48 r49 q1 v in v out (force) v out (sense) gnd 00419-d-040 figure 40. simplified schematic device power dissipation considerations the adr390/ADR391/adr392/adr395 are capable of deli- vering load currents to 5 ma, with an input voltage that ranges from 2.8 v (ADR391 only) to 15 v. when these devices are used in applications with large input voltages, care should be taken to avoid exceeding the specified maximum power dissipation or junction temperature because it could result in premature device failure. the following formula should be used to calcu-late a devices maximum junction temperature or dissipation: ja a j d t C t p = in this equation, t j and t a are, respectively, the junction and ambient temperatures. p d is the device power dissipation, and ja is the device package thermal resistance. shutdown mode operation the adr390/ADR391/adr392/adr395 include a shutdown feature that is ttl/cmos level compatible. a logic low or a zero volt condition on the shdn pin is required to turn the devices off. during shutdown, the output of the reference becomes a high impedance state, where its potential would then be determined by external circuitry. if the shutdown feature is not used, the shdn pin should be connected to v in (pin 2).
adr390/ADR391/adr392/adr395 rev. f | page 17 of 20 applications basic voltage reference connection the circuit shown in figure 41 illustrates the basic configuration for the adr39x family. decoupling capacitors are not required for circuit stability. the adr39x family is capable of driving capacitive loads from 0 f to 10 f. however, a 0.1 f ceramic output capacitor is recommended to absorb and deliver the charge, as required by a dynamic load. shutdown input c b 0.1 f c b 0.1 f * * output *not required adr39x shdn v in v out(s) gnd v out(f) 00419-d-041 figure 41. basic configuration for the adr39x family stacking reference ics for arbitrary outputs some applications may require two reference voltage sources, which are a combined sum of standard outputs. figure 42 shows how this stacked output reference can be implemented. v out(f) v out(s) gnd v in v out2 v out1 u2 1 2 3 4 5 u1 c2 0.1 f v in 3 4 1 2 c2 0.1 f v out(f) v out(s) gnd v in 5 output table u1/u2 adr390/adr390 ADR391/ADR391 adr392/adr392 adr395/adr395 v out1 (v) 2.048 2.5 4.096 5 v out2 (v) 4.096 5.0 8.192 10 00419-d-042 shdn shdn figure 42. stacking voltage references with the adr390/ADR391/adr392/adr395 two reference ics are used, fed from an unregulated input, v in . the outputs of the individual ics are simply connected in series, which provides two output voltages, v out1 and v out2 . v out1 is the terminal voltage of u1, while v out2 is the sum of this voltage and the terminal voltage of u2. u1 and u2 are simply chosen for the two voltages that supply the required outputs (see the output table in figure 42). for example, if both u1 and u2 are ADR391s, v out1 is 2.5 v and v out2 is 5.0 v. while this concept is simple, a precaution is required. since the lower reference circuit must sink a small bias current from u2 plus the base current from the series pnp output transistor in u2, either the external load of u1 or r1 must provide a path for this current. if the u1 minimum load is not well defined, the r1 resistor should be used and set to a value that will conservatively pass 600 a of current with the applicable v out1 across it. note that the two u1 and u2 reference circuits are treated locally as macrocells; each has its own bypasses at input and output for best stability. both u1 and u2 in this circuit can source dc currents up to their full rating. the minimum input voltage, v in , is determined by the sum of the outputs, v out2 , plus the dropout voltage of u2. a negative precision refe rence without precision resistors a negative reference can be easily generated by adding an a1 op amp and is configured as shown in figure 43. v outf and v outs are at virtual ground and, therefore, the negative reference can be taken directly from the output of the op amp. the op amp must be dual-supply, low offset, and rail-to-rail if the negative supply voltage is close to the reference output. +v dd ?v dd ?v ref v out(s) v out(f) v in gnd a1 2 4 3 5 1 00419-d-043 shdn figure 43. negative reference
adr390/ADR391/adr392/adr395 rev. f | page 18 of 20 general-purpose current source many times in low power applications, the need arises for a precision current source that can operate on low supply vol- tages. adr390/ADR391/adr392/adr395 can be configured as a precision current source. as shown in figure 45, the circuit configuration is a floating current source with a grounded load. the references output voltage is bootstrapped across r set , which sets the output current into the load. with this configuration, circuit precision is maintained for load currents in the range from the references supply current, typically 90 a to approximately 5 ma. v in adr39x gnd v out i out = i set + i sy (i set ) r1 i sy adjust r set p1 r l v out v in r1 0.1 f i sy (i set ) i set 00419-d-044 shdn figure 44. a general-purpose current source high power performance with current limit in some cases, the user may want higher output current delivered to a load and still achieve better than 0.5% accuracy out of the adr39x. the accuracy for a reference is normally specified on the data sheet with no load. however, the output voltage changes with load current. the circuit shown in figure 45 provides high current without compromising the accuracy of the adr39x. the series pass transistor q1 provides up to 1 a load current. the adr39x delivers only the base drive to q1 through the force pin. the sense pin of the adr39x is a regulated output and is connected to the load. the transistor q2 protects q1 during short-circuit limit faults by robbing its base drive. the maximum current is i lmax 0.6 v/ r s i l v in r1 4.7k ? q2 q2n2222 q2n4921 q1 r s r l shdn v in v out (sense) v out (force) gnd u1 adr39x 00419-d-045 figure 45. adr39x for high power performance with current limit a similar circuit function can also be achieved with the darlington transistor configuration, as shown in figure 46. adr39x v in r1 4.7k ? q2 q2n2222 q2n4921 r s r l v in v out (sense) v out (force) gnd q1 u1 00419-d-046 shdn figure 46. adr39x for high output current with darlington drive configuration
adr390/ADR391/adr392/adr395 rev. f | page 19 of 20 outline dimensions pin 1 1.60 bsc 2.80 bsc 1.90 bsc 0.95 bsc 13 4 5 2 0.20 0.08 0.60 0.45 0.30 8 4 0.50 0.30 0.10 max seating plane 1.00 max 0.90 0.87 0.84 compliant to jedec standards mo-193ab 2.90 bsc figure 47. 5-lead thin small outline transistor package [tsot] (uj-5) dimensions shown in millimeters ordering guide models output voltage (v o ) initial accuracy (mv) (%) temperature coefficient (ppm/c) package description package option branding number of parts per reel temperature range adr390aujz-reel7 1 2.048 6 0.29 25 tsot uj-5 r0a 3,000 C40c to +125c adr390aujz-r2 1 2.048 6 0.29 25 tsot uj-5 r0a 250 C40c to +125c adr390bujz-reel7 1 2.048 4 0.19 9 tsot uj-5 r0b 3,000 C40c to +125c adr390bujz-r2 1 2.048 4 0.19 9 tsot uj-5 r0b 250 C40c to +125c ADR391aujz-reel7 1 2.5 6 0.24 25 tsot uj-5 r1a 3,000 C40c to +125c ADR391aujz-r2 1 2.5 6 0.24 25 tsot uj-5 r1a 250 C40c to +125c ADR391bujz-reel7 1 2.5 4 0.16 9 tsot uj-5 r1b 3,000 C40c to +125c ADR391bujz-r2 1 2.5 4 0.16 9 tsot uj-5 r1b 250 C40c to +125c adr392aujz-reel7 1 4.096 6 0.15 25 tsot uj-5 rca 3,000 C40c to +125c adr392aujz-r2 1 4.096 6 0.15 25 tsot uj-5 rca 250 C40c to +125c adr392bujz-reel7 1 4.096 5 0.12 9 tsot uj-5 rcb 3,000 C40c to +125c adr392bujz-r2 1 4.096 5 0.12 9 tsot uj-5 rcb 250 C40c to +125c adr395aujz-reel7 1 5.0 6 0.12 25 tsot uj-5 rda 3,000 C40c to +125c adr395aujz-r2 1 5.0 6 0.12 25 tsot uj-5 rda 250 C40c to +125c adr395bujz-reel7 1 5.0 5 0.10 9 tsot uj-5 rdb 3,000 C40c to +125c adr395bujz-r2 1 5.0 5 0.10 9 tsot uj-5 rdb 250 C40c to +125c 1 z = pb-free part.
adr390/ADR391/adr392/adr395 rev. f | page 20 of 20 notes ? 2005 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. c00419C0C5/05(f)

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