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february 2008 rev 15 1/19 19 ST485B st485c low power rs-485/rs-422 transceiver features low quiescent current: 300 a designed for rs-485 interface application -7 v to 12 v common mode input voltage range driver maintains high impedance in 3-state or with the power off 70 mv typical input hysteresis 30 ns propagation delay, 5 ns skew operate from a single 5 v supply current limiting and thermal shutdown for driver overload protection allows up to 64 transceivers on the bus description the st485 is al low power transceiver for rs-485 and rs-422 communication. each part contains one driver and one receiver. this transceiver draw 300 a (typ.) of supply current when unloaded or fully loaded with disabled drivers. it operates from a single 5 v supply. driver is short-circuit current limited and is protected against excessive power dissipation by thermal shutdown circuitry that placed the driver outputs into a high-impedance state. the st485 is designed for bi-directional data communications on multipoint bus transmission line (half-duplex applications). the st485 is available in three temperature range: commercial (0 c to 70 c), industrial (-40 c to 85 c) and automotive (-55 c to 125 c). dip-8 so-8 table 1. device summary order code temperature range package packaging st485cn 0 to 70 c dip-8 50 parts per tube / 40 tube per box ST485Bn -40 to 85 c dip-8 50 parts per tube / 40 tube per box st485cdr 0 to 70 c so-8 (tape and reel) 2500 parts per reel ST485Bdr -40 to 85 c so-8 (tape and reel) 2500 parts per reel www.st.com
contents ST485B - st485c 2/19 contents 1 pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 truth tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1 driver switching characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2 receiver switching characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 test circuit and typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
ST485B - st485c pin configuration 3/19 1 pin configuration figure 1. pin connections table 2. pin description pin n symbol name and function 1 ro receiver output 2 re receiver output enable 3 de driver output enable 4didriver input 5 gnd ground 6 a non-inverting receiver input and non-inverting driver output 7 b inverting receiver input and inverting driver output 8v cc supply voltage
truth tables ST485B - st485c 4/19 2 truth tables note: x = don?t care; z = high impedance note: x = don?t care; z = high impedance table 3. truth table (driver) inputs outputs re de di b a xhhlh xhlhl xlxzz table 4. truth table (receiver) inputs outputs re de a-b ro ll +0.2v h ll -0.2v l l l inputs open h hlx z
ST485B - st485c maximum ratings 5/19 3 maximum ratings note: absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these condition is not implied. v+ and v- can have a maximum magnitude of +7 v, but their absolute addition can not exceed 13 v. table 5. absolute maximum ratings symbol parameter value unit v cc supply voltage 7 v v i control input voltage (re , de) -0.5 to (v cc + 0.5) v v di driver input voltage (di) -0.5 to (v cc + 0.5) v v do driver output voltage (a, b) 14 v v ri receiver input voltage (a, b) 14 v v ro receiver output voltage (ro) -0.5 to (v cc + 0.5) v
electrical characteristics ST485B - st485c 6/19 4 electrical characteristics table 6. dc electrical characteristics v cc = 5 v 5 %, t a = t min to t max , unless otherwise specified. typical values are referred to t a = 25 c) symbol parameter test conditions (1) value unit -40 to 85 c -55 to 125 c min. typ. max. min. max. v od1 differential driver output (no load) 55v v od2 differential driver output (with load) r l = 27 (rs-485) figure 2 r l = 50 (rs-422) figure 2 1.5 5 5 1.4 5 5 v v v od change in magnitude of driver differential output voltage for complementary output states r l = 27 or 50 figure 2 0.2 0.2 v v oc driver common-mode output voltage r l = 27 or 50 figure 2 33v v oc change in magnitude of driver common-mode output voltage for complementary output states r l = 27 or 50 figure 2 0.2 0.2 v v ih input high voltage re , de, di 2.0 2.0 v v il input low voltage re , de, di 0.8 0.8 v i in1 input current re , de, di 2 2a i in2 input current (a, b) v cm = 0v or 5.25v, v de = 0v v in = 12v v in = -7v 1 -0.8 1 -0.8 ma ma v th receiver differential threshold voltage v cm = -7 to 12v -0.2 0.2 -0.2 0.2 v v th receiver input hysteresis v cm = 0v 70 mv v oh receiver output high voltage i o = -4ma, v id = 200mv 3.5 3.4 v v ol receiver output low voltage i o = 4ma, v id = -200mv 0.4 0.55 v i ozr 3-state (high impedance) output current at receiver v o = 0.4 to 2.4v 1 1a r in receiver input resistance v cm = -7 to 12v 24 24 k i cc no load supply current (2) v re = 0v or v cc v de = v cc v de = 0v 400 300 900 500 900 500 a a
ST485B - st485c electrical characteristics 7/19 i osd1 driver short-circuit current, v o =high v o = -7 to 12v (3) 35 25035250ma i osd2 driver short-circuit current, v o =low v o = -7 to 12v (3) 35 25035250ma i osr receiver short-circuit current v o = 0v to v cc 7 95795ma 1. all currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to devi ce ground unless specified. 2. supply current specification is valid for loaded transmitters when v de = 0v 3. applies to peak current. see ty pical operating characteristics. table 6. dc electrical characteristics (continued) v cc = 5 v 5 %, t a = t min to t max , unless otherwise specified. typical values are referred to t a = 25 c) symbol parameter test conditions (1) value unit -40 to 85 c -55 to 125 c min. typ. max. min. max. table 7. driver switching characteristics v cc = 5 v 5 %, t a = t min to t max , unless otherwise specified. typical values are referred to t a = 25 c symbol parameter test conditions (1) value unit -40 to 85 c -55 to 125c min. typ. max. min. max. t plh t phl propagation delay input to output r diff = 54 , c l1 = c l2 = 100pf (see figure 4 and figure 6 ) 10 30 60 70 ns t sk output skew to output r diff = 54 , c l1 = c l2 = 100pf (see figure 4 and figure 6 ) 510 10ns t tlh t thl rise or fall time r diff = 54 , c l1 = c l2 = 100pf (see figure 4 and figure 6 ) 3 15 40 3 45 ns t pzh output enable time c l = 100pf, s2 = closed (see figure 5 and figure 7 ) 70 90 90 ns t pzl output enable time c l = 100pf, s1 = closed (see figure 5 and figure 7 ) 70 90 90 ns t plz output disable time c l = 15pf, s1 = closed (see figure 5 and figure 7 ) 70 90 90 ns t phz output disable time c l = 15pf, s2 = closed (see figure 5 and figure 7 ) 70 90 90 ns 1. all currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to devi ce ground unless specified.
electrical characteristics ST485B - st485c 8/19 table 8. receiver switching characteristics v cc = 5 v 5%, t a = t min to t max , unless otherwise specified. typical values are referred to t a = 25 c) symbol parameter test conditions (1) value unit -40 to 85 c -55 to 125c min. typ. max. min. max. t plh t phl propagation delay input to output r diff =54 , c l1 = c l2 = 100pf (see figure 4 and figure 8 ) 20 130 210 230 ns t skd differential receiver skew r diff =54 , c l1 = c l2 = 100pf (see figure 4 and figure 8 ) 13 ns t pzh output enable time c rl = 15pf, s1 = closed (see fig. 2 and figure 9 ) 20 50 56 ns t pzl output enable time c rl = 15pf, s2 = closed (see fig. 2 and figure 9 ) 20 50 56 ns t plz output disable time c rl = 15pf, s1 = closed (see fig. 2 and figure 9 ) 20 50 56 ns t phz output disable time c rl = 15pf, s2 = closed (see fig. 2 and figure 9 ) 20 50 56 ns f max maximum data rate 2.5 2.5 mbps 1. all currents into device pins are positive; all cuttents out of device pins are negative; all voltages are referenced to devi ce ground unless specified
ST485B - st485c test circuit and typical characteristics 9/19 5 test circuit and typical characteristics figure 2. driver dc test load figure 3. receiver timing test load figure 4. drive/receiver timing test circuit figure 5. driver timing test load
test circuit and typical characteristics ST485B - st485c 10/19 figure 6. driver propagation delay figure 7. driver enable and disable time
ST485B - st485c test circuit and typical characteristics 11/19 figure 8. receiver propagation delay figure 9. receiver enable and disable time
test circuit and typical characteristics ST485B - st485c 12/19 figure 10. receiver output current vs output low voltage figure 11. receiver output current vs output high voltage figure 12. driver output current vs output low voltage figure 13. driver output current vs output high voltage figure 14. supply current vs temperature figure 15. receiver high level output voltage vs temperature
ST485B - st485c test circuit and typical characteristics 13/19 figure 16. receiver low level output voltage vs temperature figure 17. differential driver output voltage vs temperature
package mechanical data ST485B - st485c 14/19 6 package mechanical data in order to meet environmental requirements, st offers these devices in ecopack? packages. these packages have a lead-free second level interconnect. the category of second level interconnect is marked on the package and on the inner box label, in compliance with jedec standard jesd97. the maximum ratings related to soldering conditions are also marked on the inner box label. ecopack is an st trademark. ecopack specifications are available at: www.st.com
ST485B - st485c package mechanical data 15/19 dim. mm. inch. min. typ. max. min. typ. max. a 3 . 3 0.1 3 0 a 1 0.7 0.02 8 b1. 39 1.65 0.055 0.065 b1 0. 9 1 1.04 0.0 3 6 0.041 b 0.5 0.020 b 10. 38 0.5 0.015 0.020 d 9 . 8 0. 38 6 e 8 . 8 0. 3 46 e 2.54 0.100 e 3 7.62 0. 3 00 e4 7.62 0. 3 00 f 7.1 0.2 8 0 i4. 8 0.1 89 l 3 . 3 0.1 3 0 z 0.44 1.6 0.017 0.06 3 pla s tic dip- 8 mechanical data p001f
package mechanical data ST485B - st485c 16/19 dim. mm. inch. min. typ. max. min. typ. max. a1. 3 5 1.75 0.05 3 0.06 9 a1 0.10 0.25 0.04 0.010 a2 1.10 1.65 0.04 3 0.065 b0. 33 0.51 0.01 3 0.020 c0.1 9 0.25 0.007 0.010 d4. 8 0 5.00 0.1 89 0.1 9 7 e 3 . 8 0 4.00 0.150 0.157 e 1.27 0.050 h5. 8 0 6.20 0.22 8 0.244 h 0.25 0.50 0.010 0.020 l 0.40 1.27 0.016 0.050 k 8 (m a x.) ddd 0.1 0.04 s o- 8 mechanical data 001602 3 /c
ST485B - st485c package mechanical data 17/19 dim. mm. inch. min. typ. max. min. typ. max. a 33 0 12. 99 2 c 12. 8 1 3 .2 0.504 0.51 9 d 20.2 0.7 9 5 n60 2. 3 62 t 22.4 0. 88 2 ao 8 .1 8 .5 0. 3 1 9 0. 33 5 bo 5.5 5. 9 0.216 0.2 3 2 ko 2.1 2. 3 0.0 8 2 0.0 9 0 po 3 . 9 4.1 0.15 3 0.161 p7. 98 .1 0. 3 11 0. 3 1 9 tape & reel s o- 8 mechanical data
revision history ST485B - st485c 18/19 7 revision history table 9. document revision history date revision changes 21-mar-2006 12 order codes has been updated and new template. 02-aug-2006 13 mistake in cover page first row ma ==> a. 08-nov-2006 14 added: ta b l e 1 . 07-feb-2008 15 modified: table 1 on page 1 .
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