exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 description ? rs-485 and rs-422 transceiver ? operates from a single +3.3v supply ? interoperable with +5.0v logic ? driver/receiver enable ? -7v to + 2v common-mode input voltage range ? allows up to 32 transceivers on the serial bus ? compatibility with industry standard 7576 pinout ? driver output short-circuit protection sp3485 +3.3v low power half-duplex rs-485 transceiver with 10mbps data rate the sp3485 device is a +3.3v low power half-duplex transceiver that meets the specifca - tions of the rs-485 and rs-422 serial protocols. this device is pin-to-pin compatible with the exar sp48 , sp483 and sp485 devices as well as popular industry standards. the sp3485 features the exar bicmos process, allowing low power operation without sacrifcing performance. the sp3485 can meet the electrical specifcations of the rs-485 and rs-422 serial protocols up to 0mbps under load.
2 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 absolute maximum ratings these are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifcations below is not implied. exposure to absolute maximum rating conditions for extended periods of time may affect reliability. v cc .....................................................................+6.0v input voltages logic....................................-0.3v to +6.0v drivers.................................-0.3v to +6.0v receivers.........................................+/-5v output voltages drivers.............................................+/-5v receivers............................-0.3v to +6.0v storage temperature.......................-65?c to +150?c power dissipation 8-pin nsoic...................................................600mw (derate 6.90mw/oc above +70oc) electrical characteristics t amb = t min to t max and v cc = +3.3v +/-5% unless otherwise noted. parameters min. typ. max. units conditions sp3485 driver dc characteristics differential output voltage gnd vcc volts unloaded; r = ? ; figure 1 differential output voltage 2 vcc volts with load; r = 50? (rs-422); figure differential output voltage .5 vcc volts with load; r = 27? (rs-485); figure change in magnitude of driver differential output voltage for complimentary states 0.2 volts r = 27? or r = 50?; figure 1 driver common mode output voltage 3 volts r = 27? or r = 50?; figure 1 input high voltage 2.0 volts applies to de, di, re input low voltage 0.8 volts applies to de, di, re input current +/-0 a applies to de, di, re driver short circuit current v out = high +/-250 ma -7v v o +12v; figure 8 driver short circuit current v out = low +/-250 ma -7v v o +12v; figure 8 sp3485 driver ac characteristics maximum data rate 0 mbps re = v cc , de = v cc driver input to output, t plh 20 40 60 ns figures 2 & 9 driver input to output, t phl 20 40 60 ns figures 2 & 9 differential driver skew 2 0 ns |t do - t do2 |, figures 2 and 0 driver rise or fall time 5 20 ns from 0%-90%; figures 3 and 0
3 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 parameters min. typ. max. units conditions sp3485 driver ac characteristics continued driver enable to output high 52 20 ns figures 4 and driver enable to output low 60 20 ns figures 5 and driver disable time from low 40 20 ns figures 5 and driver disable time from high 60 20 ns figures 4 and sp3485 receiver dc characteristics differential input threshold -0.2 +0.2 volts -7v v cm +12v input hysteresis 20 mv v cm = 0v output voltage high vcc-0.4 volts v id = +200mv, - .5ma output voltage low 0.4 volts v id = -200mv, 2.5ma three-state (high impedance) output current +/- a 0v v o v cc ; re = v cc input resistance 2 5 k? -7v v cm +12v input current (a, b); v in = 2v +.0 ma de = 0v, v cc = 0v or 3.6v, v in = 2v input current (a, b); v in = -7v -0.8 ma de = 0v, v cc = 0v or 3.6v, v in = -7v short circuit current 7 60 ma 0v v cm v cc sp3485 receiver ac characteristics maximum data rate 0 mbps re = 0v, de = 0v receiver input to output, t plh 40 70 00 ns figures 6 and 2 receiver input to output, t plh 70 ns t amb = +25c, vcc = 3.3v, figures 6 and 2 receiver input to output, t phl 40 70 00 ns figures 6 and 2 receiver input to output, t phl 70 ns t amb = +25c, vcc = 3.3v, figures 6 and 2 differential receiver skew 4 ns t rskew = |t rphl - t rplh |, figures 6 and 2 receiver enable to output low 35 60 ns figures 7 and 3, s closed, s 2 open receiver enable to output high 35 60 ns figures 7 and 3, s 2 closed, s open receiver disable from low 35 60 ns figures 7 and 3, s closed, s 2 open receiver disable from high 35 60 ns figures 7 and 3, s 2 closed, s open power requirements supply current , no load 000 2000 a re, di = 0v or v cc ; de = v cc supply current , no load 800 500 a re = 0v, di = 0v or v cc , de = 0v electrical characteristics t amb = t min to t max and v cc = +3.3v +/-5% unless otherwise noted.
4 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 pin function pin - ro - receiver output pin 2 - re - receiver output enable active low pin 3 - de - driver output enable active high pin 4 - di - driver input pin 5 - gnd - ground connection pin 6 - a - non-inverting driver output/receiver input pin 7 - b - inverting driver output/receiver input pin 8 - vcc - positive supply pin function sp3485
5 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 test circuits r r v oc d vcc v od figure . driver dc test load circuit generator (note 1) 50? c l out d v cc r l = 60? c l = 15pf (note 2) figure 3. driver differential output delay and transition time circuit. generator (note 1) 50? s1 r l = 110? out c l = 50pf (note 2) v om = 1.5v v oh + v ol 2 d figure 4. driver enable and disable timing circuit, output high figure 2. driver propagation delay test circuit generator (note 1) 50? v cc s1 v dm r l = 27? ou t c l = 15p f (note 2) v om = 1.5 v v oh + v ol 2 d figure 5. driver enable and disable timing circuit, output low generato r (note 1) 50? s1 r l = 110? out c l = 50p f (note 2) d 0v or 3v v cc generator (note 1) 50? 1.5v 0v v id r ou t c l = 15pf (note 2 ) v om = v cc 2 figure 6. receiver propagation delay test circuit 1.5v -1.5v s3 v id generato r (note 1) 50? c l = 15pf (note 2) r 1k s1 s2 v cc a/y d di = 0 or vcc b/z de = 0 or vcc i os d 100? -7v to +12v v figure 7. receiver enable and disable timing circuit figure 8. driver short circuit current limit test note : the input pulse is supplied by a generator with the following characteristics: prr = 250khz, 50% duty cycle, t r < 6.0ns, z o = 50?. note 2: c l includes probe and stray capacitance.
6 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 figure 9. driver propagation delay waveforms 0v v oh t plh t phl v om t phl t plh 3v v ol v oh 1.5v 1.5v input y output v om z output v ol v om v om v om = v oh + v ol 2 1.5v switching waveforms figure 3. receiver enable and disable waveforms in 1.5v t do1 1.5v t do2 3v 0v out 50% 50% 10% 10% 90% 90% t td t td 2.0v -2.0v figure 0. driver differential output delay and transition time waveforms 0v v oh t pzh 0.25v t phz v om t pzl t plz 3v v ol v cc 1.5v 1.5v de output high v om 0.25v 0v output lo w v om = v oh + v ol 2 1.5v 3v 0v v cc t rplh 1.5v t rphl v om v om 0v 1.5v input output v om = v cc 2 figure 2. receiver propagation delay waveforms figure . driver enable and disable timing waveforms 3v 0v t prhz 1.5v t przh t prsh 1.5v 1.5v 10% 0v v oh re output s1 is open s2 is closed s3 = 1.5 v 3v 0v t prlz 1.5v t przl t prsl 1.5v 1.5v 10% v cc re output s1 is closed s2 is open s3 = -1.5v v ol
7 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 the sp3485 is a member in the family of +3.3v low power half-duplex transceivers that meet the electrical specifcations of the rs-485 and rs-422 serial protocols. this device is pin-to-pin compatible with the exar sp48 , sp483 and sp485 devices as well as popular industry standards. the sp3485 feature exar's bicmos process allowing low power operation without sacrifcing performance. driver the driver outputs of the sp3485 are dif - ferential outputs meeting the rs-485 and rs-422 standards. the typical voltage output swing with no load will be 0 volts to +3.3 volts. with a load of 54? across the differential outputs, the drivers can maintain greater than .5v voltage levels. the driver of the sp3485 has a driver enable control line which is active high. a logic high on de (pin 3) will enable the differential driver outputs. a logic low on the de (pin 3) will tri-state the driver outputs. the driver of the sp3485 operates up to 0mbps. the 250ma i sc maximum limit on the driver output allows the sp3485 to withstand an infnite short circuit over the -7.0v to + 2v common mode range without catastrophic damage to the ic. receiver the sp3485 receiver has differential inputs with an input sensitivity of 200mv. input impedance of the receiver is typically 15k? (12k? minimum). a wide common mode range of -7v to + 2v allows for large ground potential differences between systems. the receiver is equipped with a fail-safe feature that guarantees the receiver output will be in a high state when the input is left uncon - nected. the receiver of the sp3485 operates up to 0mbps. the receiver of the sp3485 has an enable control line which is active low. a logic low on re (pin 2) will enable the differential receiver. a logic high on re (pin 2) of the sp3485 will disable the receiver. description inputs outputs re de di line condition b a x no fault 0 x 0 no fault 0 x 0 x x z z inputs outputs re de a - b r 0 0 +0.2v 0 0 -0.2v 0 0 0 inputs open 0 x z table . transmit function truth table table 2. receive function truth table
8 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692
9 exar corporation 48720 kato road, fremont ca, 94538 ? 50-668-70 7 ? www.exar.com sp3485_00_0692 ordering information model temperature range package types sp3485cn-l ....................................................................... 0c to +70c ................................................................................................ 8-pin nsoic sp3485cn-l/tr ................................................................. 0c to +70c ................................................................................................ 8-pin nsoic SP3485EN-L...................................................................... -40c to +85c..............................................................................................8-pin nsoic SP3485EN-L/tr................................................................ -40c to +85c..............................................................................................8-pin nsoic revision histor y date revision description 0/5/02 -- legacy sipex datasheet 06/9/2 .0.0 convert to exar format. update ordering information and add new figure 8 - driver short circuit current limit test circuit. remove eol device sp348 . notice exar corporation reserves the right to make changes to any products contained in this publication in order to improve design, performance or reliabil - ity. exar corporation assumes no representation that the circuits are free of patent infringement. charts and schedules contained herein are only for illustration purposes and may vary depending upon a user's specifc application. while the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. exar corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to signifcantly af fect its safety or effectiveness. products are not authorized for use in such applications unless exar corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized ; (b) the user assumes all such risks; (c) potential liability of exar corporation is adequately protected under the circumstances. copyright 202 exar corporation datasheet june 202 for technical support please email exar's serial technical support group at: serialtechsupport@exar.com reproduction, in part or whole, without the prior written consent of exar corporation is prohibited. note: /tr = tape and reel
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