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rev. e a adm1485 5 v low power eia rs-485 transceiver one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ?2003 analog devices, inc. all rights reserved. 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. 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. functional block diagram 8-lead adm1485 r d ro re di v cc b a gnd de features meets eia rs-485 standard 30 mbps data rate single 5 v supply ? v to +12 v bus common-mode range high speed, low power bicmos thermal shutdown protection short-circuit protection driver propagation delay: 10 ns receiver propagation delay: 15 ns high-z outputs with power off superior upgrade for ltc1485 applications low power rs-485 systems dte-dce interface packet switching local area networks data concentration data multiplexers integrated services digital network (isdn) general description the adm1485 is a differential line transceiver suitable for high speed bidirectional data communication on multipoint bus trans- mission lines. it is designed for balanced data transmission and complies with both rs-485 and rs-422 eia standards. the part contains a differential line driver and a differential line receiver. both the driver and the receiver may be enabled independently. when disabled, the outputs are three-stated. the adm1485 operates from a single 5 v power supply. excessive power dissipation caused by bus contention or by output shorting is prevented by a thermal shutdown circuit. this feature forces the driver output into a high impedance state if, during fault condi- tions, a significant temperature increase is detected in the internal driver circuitry. up to 32 transceivers may be connected simultaneously on a bus, but only one driver should be enabled at any time. it is important, therefore, that the remaining disabled drivers do not load the bus. to ensure this, the adm1485 driver features high output im pedance when disabled and also when powered down. this minimizes the loading effect when the transceiver is not being used. the high impedance driver output is maintained over the entire common-mode voltage range from ? v to +12 v. the receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating). the adm1485 is fabricated on bicmos, an advanced mixed technology process combining low power cmos with fast switching bipolar technology. all inputs and outputs contain protection against esd; all driver outputs feature high source and sink current capability. an epitaxial layer is used to guard against latch-up. the adm1485 features extremely fast switching speeds. minimal driver propagation delays permit transmission at data rates up to 5 mbps while low skew minimizes emi interference. the part is fully specified over the commercial and industrial temperature range and is available in pdip, soic, and small msop packages.
rev. e e2e adm1485especifications (v cc = 5 v 5%. all specifications t min to t max , unless otherwise noted.) parameter min typ max unit test conditions/comments driver differential output voltage, v od 5.0 v r = ? ? ? ? ? ? ? ? ? ? ? ? re ? o/p e r ? ? ? ? ? ? ? ? 5%. all specifications t min to t max , unless otherwise noted.)
rev. e adm1485 e3e absolute maximum ratings * (t a = 25 re r o o ro pop re roe ro e oe r/ o r /o p re r
rev. e e4e adm1485 t est circuits v od r r v oc test circuit 1. driver voltage measurement v od3 60 375 375 v tst test circuit 2. driver voltage measurement r ldiff a b c l1 c l2 test circuit 3. driver propagation delay de 0v or 3v de in a b s1 c l v out r l s2 v cc test circuit 4. driver enable/disable re a b c l v out test circuit 5. receiver propagation delay re +1.5v re in s1 c l v out r l s2 v cc e1.5v test circuit 6. receiver enable/disable switching characteristics 3v 0v b a 0v ev o v o 90% point 10% point t r t skew = t plh e t phl 1/2vo t plh 1.5v 1.5v t phl 90% point 10% point t f v o figure 1. driver propagation delay, rise/fall timing de a, b a, b 1.5v 2.3v 2.3v t zh t zl 1.5v 3v 0v v ol v oh 0v v ol + 0.5v v oh e 0.5v t hz t lz figure 2. driver enable/disable timing a, b ro 0v t plh 1.5v 0v t phl 1.5v v oh v ol t skew = t plh e t phl figure 3. receiver propagation delay re r r 1.5v 1.5v 1.5v t zh t zl 1.5v 3v 0v v ol v oh v ol + 0.5v v oh e 0.5v t hz t lz o/p low o/p high 0v figure 4. receiver enable/disable timing
rev. e t ypical performance characteristicseadm1485 e5e output voltage e v output current e ma 50 0 45 30 25 20 15 10 5 0 0.50 1.00 1.75 40 35 0.25 0.75 1.25 1.50 2.00 tpc 1. output current vs. receiver output low voltage output voltage e v output current e ma 0 3.50 e2 e4 e6 e8 e10 e12 e14 e16 e18 4.00 4.75 5.00 4.25 3.75 4.50 tpc 2. output current vs. receiver output high voltage temperature e c output voltage e v 4.55 e50 e25 125 025507 5 100 i = 8ma 4.50 4.45 4.40 4.35 4.30 4.25 4.20 4.15 tpc 3. receiver output high voltage vs. temperature temperature e c output voltage e v 0.40 0.35 0.15 e50 0.20 e25 0 25 50 75 100 125 i = 8ma 0.25 0.30 tpc 4. receiver output low voltage vs. temperature output voltage e v 90 0 output current e ma 0 10 20 30 40 50 60 70 80 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 tpc 5. output current vs. driver differential output voltage temperature e c 2.15 e50 differential voltage e v 1.90 1.95 2.00 2.05 2.10 e25 0 25 50 75 100 125 tpc 6. driver differential output voltage vs. temperature, r l = 26.8 ?
rev. e e6e adm1485 output voltage e v output current e ma 100 0 0 4.0 1.0 2.0 3.0 90 60 50 30 10 80 70 40 20 0.5 1.5 2.5 3.5 4.5 tpc 7. output current vs. driver output low voltage output voltage e v output current e ma 0 0 e10 e20 e30 e40 e50 e60 e70 e80 e90 e100 1.0 2.0 3.0 4.0 5.0 e110 e120 0.5 1.5 2.5 3.5 4.5 tpc 8. output current vs. driver output high voltage temperature e c e50 supply current e ma 1.0 e25 0 25 50 75 100 125 0.9 0.7 0.5 driver enabled driver disabled 1.1 0.8 0.6 tpc 9. supply current vs. temperature | t plh e t phl | temperature e c time e ns e50 0.7 0.6 0.5 0.4 e25 0 25 50 75 100 125 0.3 0.2 0.1 0 tpc 10. rx skew vs. temperature temperature e c time e ns e50 1 e25 0 25 50 75 100 125 0 2 3 4 5 6 | t phla e t phlb | | t plha e t plhb | tpc 11. tx skew vs. temperature temperature e c pwd 1.2 e50 0.8 0.6 0.4 e25 0 25 50 75 100 125 0.2 0 1.0 1.4 150 | t plh e t phl | tpc 12. tx pulse width distortion
rev. e adm1485 e7e 1, 2 a b tpc 13. unloaded driver differential outputs 1, 2 a b tpc 14. loaded driver differential outputs 4 1, 2 3 a b di ro tpc 15. driver/receiver propagation delays low to high 4 1, 2 3 a b di ro tpc 16. driver/receiver propagation delays high to low 1, 2 a b tpc 17. driver output at 30 mbps
rev. e e8e adm1485 as with any transmission line, it is important that reflections are minimized. this can be achieved by terminating the extreme ends of the line using resistors equal to the characteristic impedance of the line. stub lengths of the main line should also be kept as short as possible. a properly terminated transmission line appears purely resistive to the driver. rt rt d r dd r r d r figure 5. typical rs-485 network thermal shutdown the adm1485 contains thermal shutdown circuitry that protects the part from excessive power dissipation during fault conditions. shorting the driver outputs to a low impedance source can result in high driver currents. the thermal sensing circuitry detects the increase in die temperature and disables the driver outputs. the thermal sensing circuitry is designed to disable the driver outputs when a die temperature of 150 ? ? ? ?
rev. e adm1485 e9e outline dimensions 8-lead standard small outline package [soic] narrow body (r-8) dimensions shown in millimeters and (inches) 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) 85 4 1 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2440) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarity 0.10 controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012aa 8-lead mini small outline package [msop] (rm-8) dimensions shown in millimeters 0.80 0.60 0.40 8 0 85 4 1 4.90 bsc pin 1 0.65 bsc 3.00 bsc seating plane 0.15 0.00 0.38 0.22 1.10 max 3.00 bsc coplanarity 0.10 0.23 0.08 compliant to jedec standards mo-187aa 8-lead plastic dual in-line package [pdip] (n-8) dimensions shown in inches and (millimeters) seating plane 0.180 (4.57) max 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) 0.060 (1.52) 0.050 (1.27) 0.045 (1.14) 8 1 4 5 0.295 (7.49) 0.285 (7.24) 0.275 (6.98) 0.100 (2.54) bsc 0.375 (9.53) 0.365 (9.27) 0.355 (9.02) 0.150 (3.81) 0.135 (3.43) 0.120 (3.05) 0.015 (0.38) 0.010 (0.25) 0.008 (0.20) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) controlling dimensions are in inches; millimeter dimensions (in parentheses) are rounded-off inch equivalents for reference only and are not appropriate for use in design compliant to jedec standards mo-095aa 0.015 (0.38) min
rev. e e10e adm1485 revision history location page 9/03?data sheet changed from rev. d to rev. e. change to specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 changes to ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 updated outline dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7/03?data sheet changed from rev. c to rev. d. changes to specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 changes to absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 updated ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1/03?data sheet changed from rev. b to rev. c. change to specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 change to ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 12/02?data sheet changed from rev. a to rev. b. deleted q-8 package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . universal edits to features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 edits to general description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 edits, additions to specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 edits, additions to absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 additions to ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 tpcs updated and reformatted . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 addition of 8-lead msop package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 update to outline dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
e11e
c00063e0e9/03(e) e12e

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