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rev. 0 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 which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a adm483e one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 617/329-4700 world wide web site: http://www.analog.com fax: 617/326-8703 ? analog devices, inc., 1997 6 15 kv esd protected, emc compliant slew rate limited, eia rs-485 transceiver functional block diagram features robust rs-485 transceiver 15 kv esd protection using hbm 2 kv eft protection meets iec1000-4-4 high em immunity meets iec1000-4-3 reduced slew rate for low em interference 250 kbps data rate single +5 v 6 10% supply C7 v to +12 v bus common-mode range 12 k v input impedance short circuit protection excellent noise immunity 36 m a supply current 0.1 m a shutdown current applications low power rs-485 systems electrically harsh environments emi sensitive applications dte-dce interface packet switching local area networks d r a b di de re ro adm483e general description the adm483e is a robust, low power differential line trans- ceiver suitable for communication on multipoint bus transmis- sion lines. internal protection against electrostatic discharge (esd), electrical fast transient (eft) and electromagnetic immunity (emi) allows operation in electrically harsh environ- ments. esd protection on the i-o lines meets 15 kv when tested using the human body model. eft protection meets 2 kv in accordance with iec1000-4-4, while emi immunity is in excess of 10 v/m meeting iec1000-4-3. the level of unwanted emissions is also carefully controlled using slew limiting on the driver outputs. this reduces reflec- tions with improperly terminated cables and also minimizes electromagnetic interference. the controlled slew rate limits the data rate to 250 kbps. the adm483e is intended for balanced data transmission and complies with both eia standards rs-485 and rs-422. it contains a differential line driver and a differential line receiver and is suitable for half duplex data transmission, as the driver and receiver share the same differential pins. the input impedance on the adm483e is 12 k w , allowing up to 32 transceivers on the bus. the adm483e operates from a single +5 v 10% power sup- ply. 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 conditions, a significant temperature increase is detected in the internal driver circuitry. the receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating). the adm483e is fabricated on bicmos, an advanced mixed technology process combining low power cmos with robust bipolar technology. it is fully specified over the industrial temperature range and is available in 8-lead dip and soic packages.
C2C rev. 0 adm483eCspecifications parameter min typ max units test conditions/comments driver differential output voltage, v od 5.0 v v cc = 5.25 v. r = , figure 1 2.0 5.0 v r = 50 w (rs-422), figure 1 1.5 5.0 v r = 27 w (rs-485), figure 1 1.5 5.0 v v tst = C7 v to +12 v, figure 2, v cc 3 4.75 v d |v od | for complementary output states 0.2 v r = 27 w or 50 w , figure 1 common-mode output voltage v oc 3 v r = 27 w or 50 w , figure 1 d |v oc | for complementary output states 0.2 v r = 27 w or 50 w output short circuit current (v out = high) 250 ma C7 v v o +12 v output short circuit current (v out = low) 250 ma C7 v v o +12 v cmos input logic threshold low, v inl 1.4 0.8 v cmos input logic threshold high, v inh 2.0 1.4 v logic input current (de, di) 1.0 m a receiver differential input threshold voltage, v th C0.2 +0.2 v C7 v v cm +12 v input voltage hysteresis, d v th 70 mv v cm = 0 v input resistance 12 k w C7 v v cm +12 v input current (a, b) +1 ma v in = 12 v C0.8 ma v in = C7 v logic enable input current ( re ) 1 m a cmos output voltage low, v ol 0.4 v i out = +4.0 ma cmos output voltage high, v oh 4.0 v i out = C4.0 ma short circuit output current 7 85 ma v out = gnd or v cc three-state output leakage current 1.0 m a 0.4 v v out +2.4 v power supply current outputs unloaded, receivers enabled i cc (adm483e) 36 60 m a de = 0 v (disabled) re = 0 v 270 360 m a de = 5 v (enabled) = re = 0 v supply current in shutdown 0.1 10 m a de = 0 v, re = v cc esd/eft immunity esd protection 15 kv hbm air discharge. a, b pins 3.5 kv hbm 3015.7 contact discharge. all pins eft protection 2 kv iec1000-4-4, a, b pins emi immunity 10 v/m iec1000-4-3 specifications subject to change without notice. timing specifications parameter min typ max units test conditions/comments driver propagation delay input to output t plh , t phl 250 2000 ns r l diff = 54 w c l1 = c l2 = 100 pf, figure 5 driver o/p to o/p t skew 100 800 ns r l diff = 54 w c l1 = c l2 = 100 pf, figure 5 driver rise/fall time t r , t f 250 2000 ns r l diff = 54 w c l1 = c l2 = 100 pf, figure 5 driver enable to output valid 250 2000 ns r l = 500 w , c l = 100 pf, figure 3 driver disable timing 300 3000 ns r l = 500 w , c l = 15 pf, figure 3 receiver propagation delay input to output t plh , t phl 250 2000 ns c l = 15 pf, figure 5 skew |t plh Ct phl | 200 ns receiver enable t en1 10 50 ns r l = 1 k w , c l = 15 pf, figure 4 receiver disable t en2 10 50 ns r l = 1 k w , c l = 15 pf, figure 4 shutdown time to shutdown 50 200 600 ns driver enable from shutdown 2000 ns r l = 500 w , c l = 100 pf, figure 3 receiver enable from shutdown 2500 ns r l = 1 k w , c l = 15 pf, figure 4 specifications subject to change without notice. (v cc = +5 v 6 10%. all specifications t min to t max unless otherwise noted) (v cc = +5 v 6 10%. all specifications t min to t max unless otherwise noted.)
adm483e C3C rev. 0 absolute maximum ratings* (t a = +25 c unless otherwise noted) v cc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+7 v inputs driver input (di) . . . . . . . . . . . . . . . . C0.5 v to v cc + 0.5 v control inputs (de, re) . . . . . . . . . . C0.5 v to v cc + 0.5 v receiver inputs (a, b) . . . . . . . . . . . . . . . . . C14 v to +14 v outputs driver outputs . . . . . . . . . . . . . . . . . . . . C12.5 v to +12.5 v receiver output . . . . . . . . . . . . . . . . . C0.5 v to v cc +0.5 v esd rating: air (human body model) (a, b pins) . . 15 kv esd r ating: contact (human body model) (a, b pins) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 kv esd rating mil-std-883b method 3015 (except a, b) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 kv eft rating (iec1000-4-4) (a, b pins) . . . . . . . . . . . . 2 kv emi immunity (iec1000-4-3) . . . . . . . . . . . . . . . . . . 10 v/m power dissipation 8-pin dip . . . . . . . . . . . . . . . . . . . 727 mw q ja , thermal impedance . . . . . . . . . . . . . . . . . . +135 c/w power dissipation 8-pin soic . . . . . . . . . . . . . . . . . 470 mw q ja , thermal impedance . . . . . . . . . . . . . . . . . . +110 c/w operating temperature range industrial (a version) . . . . . . . . . . . . . . . . C40 c to +85 c storage temperature range . . . . . . . . . . . C65 c to +150 c lead temperature (soldering, 10 sec) . . . . . . . . . . . . +300 c vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220 c *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 sections of this specification is not implied. exposure to absolute maximum ratings for extended periods may affect device reliability. ordering guide model temperature range package option ADM483EAN C40 c to +85 c n-8 adm483ear C40 c to +85 c so-8 pin function description pin mnemonic function 1 ro receiver output. when enabled if a > b by 200 mv, then ro = high. if a < b by 200 mv, then ro = low. 2 re receiver output enable. a low level enables the receiver output, ro. a high level places it in a high impedance state. 3 de driver output enable. a high level enables the driver differential outputs, a and b. a low level places it in a high impedance state. 4 di driver input. when the driver is enabled a logic low on di forces a low and b high while a logic high on di forces a high and b low. 5 gnd ground connection, 0 v. 6 a noninverting receiver input a/driver output a. 7 b inverting receiver input b/driver output b. 8v cc power supply, 5 v 10%. pin configuration re de di v cc b a gnd 1 2 3 4 8 7 6 5 top view (not to scale) adm483e ro table i. selection table part no. duplex data rate low power tx/rx i cc no of tx/rx esd eft emi kb/s shutdown enable m a on bus kv kv v/m adm483e half 250 yes yes 36 32 15 210
C4C rev. 0 adm483e v od v oc r r figure 1. driver voltage measurement test circuit v od3 v tst 60 w 375 w 375 w figure 2. driver voltage measurement test circuit 2 r l s1 s2 v cc c l v out a b 0v or 3v de in de figure 3. driver enable/disable test circuit r l s2 v cc c l v out re in re s1 +15v ?5v figure 4. receiver enable/disable test circuit test circuits ?o vo 1/2vo 0v 3v 1.5v 1.5v t plh t skew vo 0v 90% point 10% point 90% point 10% point t phl b a t skew t r t f figure 6. driver propagation delay, rise/fall timing t plh t phl 0v 0v 1.5v 1.5v a? ro v ol v oh figure 8. receiver propagation delay switching characteristics rl diff c l1 c l2 d r ro re a b di figure 5. receiver propagation delay test circuit t zh 1.5v de 1.5v 3v 0v 2.3v t hz v oh v oh ?0.5v 0v a, b v ol + 0.5v t zl 2.3v t lz v ol a, b figure 7. driver enable/disable timing t zh 1.5v 1.5v 3v 0v 1.5v t hz v oh v oh ?0.5v 0v r v ol + 0.5v t zl 1.5v t lz v ol r re o/p low o/p high figure 9. receiver enable/disable timing
typical performance characteristicsCadm483e rev. 0 C5C output voltage ?volts 40 35 0 0 0.5 2.5 1.0 1.5 2.0 20 15 10 5 30 25 output current ?ma figure 11. receiver output low voltage vs. output current output voltage ?volts 0 0.5 5.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 output current ?ma ?0 ?0 ?0 ?0 ?0 ?0 ?0 ?0 ?0 figure 14. driver output high voltage vs. output current 10 0% 100 90 10db/div 500khz/div 0 5mhz figure 17. driver output waveform and fft plot transmitting @ 150 khz output voltage ?volts 0 ? ?0 3.4 3.6 5.0 3.8 4.0 4.2 4.4 4.6 4.8 ?0 ?5 output current ?ma figure 12. receiver output high voltage vs. output current output voltage ?volts 80 0 0 0.5 4.5 1.0 1.5 2.0 3.0 3.5 4.0 2.5 70 40 30 20 10 60 50 output current ?ma figure 15. driver differential output voltage vs. output current limit 30 200 frequency ?mhz 80 70 60 50 40 30 20 10 0 db? figure 18. radiated emissions output voltage ?volts 0 output current ?ma 0.5 3.0 1.0 1.5 2.0 2.5 90 80 0 40 30 20 10 70 50 60 figure 13. driver output low voltage vs. output current 10 0% 100 90 t t t ro di figure 16. adm483e driving 4000 ft. of cable log frequency (0.15?0) ?mhz 0.3 0.6 1361030 80 0 70 40 30 20 10 60 50 limit db? figure 19. conducted emissions
C6C rev. 0 adm483e general information the adm483e is a ruggedized rs-485 transceiver that operates from a single +5 v supply. it contains protection against radiated and conducted interfer- ence, including high levels of electrostatic discharge. it is ideally suited for operation in electrically harsh environ- ments or where cables may be plugged/unplugged. it is also immune to high rf field strengths without special shielding precautions. it is intended for balanced data transmission and complies with both eia standards rs-485 and rs-422. it con- tains a differential line driver and a differential line receiver, and is suitable for half duplex data transmission as the driver and receiver share the same differential pins. the input impedance on the adm483e is 12 k w , allowing up to 32 transceivers on the differential bus. the adm483e operates from a single +5 v 10% 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 conditions, a significant temperature increase is detected in the internal driver circuitry. the receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating). a high level of robustness is achieved using internal protection circuitry, eliminating the need for external protection compo- nents such as tranzorbs or surge suppressors. low electromagnetic emissions are achieved using slew limited drivers, minimizing interference both conducted and radiated. the adm483 can transmit at data rates up to 250 kbps. a typical application for the adm483e is illustrated in figure 20. this shows a half-duplex link where data may be transferred at rates up to 250 kbps. a terminating resistor is shown at both ends of the link. this termination is not critical since the slew rate is co ntrolled by the adm483e and reflections are minimized. the communications network may be extended to include multipoint connections as shown in figure 30. up to 32 transceivers may be connected to the bus. adm483e adm483e rs485/rs-422 link +5v +5v 0.1? 0.1? v cc v cc re ro di de di de b a gnd b a gnd re ro figure 20. typical half-duplex link application tables ii and iii show the truth tables for transmitting and receiving. table ii. transmitting truth table inputs outputs re de di b a x1101 x1010 0 0 x hi-z hi-z 1 0 x hi-z hi-z x = dont care. table iii. receiving truth table inputs outputs re de a-b ro 00 3 +0.2 v 1 00 C0.2 v 0 0 0 inputs o/c 1 1 0 x hi-z x = dont care. esd/eft transient protection scheme the adm483e uses protective clamping structures on its inputs and outputs that clamp the voltage to a safe level and dissipates the energy present in esd (electrostatic) and eft (electrical fast transients) discharges. the protection structure achieves esd protection up to 15 kv according to the human body model, and eft protection up to 2 kv on all i-o lines. esd testing two coupling methods are used for esd testing, contact discharge and air-gap discharge. contact discharge calls for a direct connection to the unit being tested. air-gap discharge uses a higher test voltage but does not make direct contact with the unit under test. with air discharge, the discharge gun is moved toward the unit under test, developing an arc across the air gap, hence the term air-discharge. this method is influenced by humidity, temperature, barometric pressure, distance and rate of closure of the discharge gun. the contact-discharge method, while less realistic, is more repeatable and is gaining acceptance and preference over the air-gap method. although very little energy is contained within an esd pulse, the extremely fast rise time, coupled with high voltages, can cause failures in unprotected semiconductors. catastrophic destruction can occur immediately as a result of arcing or heating. even if catastrophic failure does not occur immedi- ately, the device may suffer from parametric degradation, which may result in degraded performance. the cumulative effects of continuous exposure can eventually lead to complete failure. high voltage generator device under test esd test method r2 c1 human body model 1.5k 100pf c1 r2 figure 21. esd generator
adm483e C7C rev. 0 i-o lines are particularly vulnerable to esd damage. simply touching or plugging in an i-o cable can result in a static discharge that can damage or completely destroy the interface product connected to the i-o port. it is, therefore, extremely important to have high levels of esd protection on the i-o lines. it is possible that the esd discharge could induce latchup in the device under test. it is therefore important that esd testing on the i-o pins be carried out while device power is applied. this type of test ing is more representative of a real world i-o discharge where the equipment is operating normally when the discharge occurs. 100% 90% 36.8% 10% i peak t rl t dl time t figure 22. human body model esd current waveform table iv. adm483e esd test results esd test method i-o pins other pins human body model: air 15 kv human body model: contact 8 kv 3.5 v fast transient burst immunity (iec1000-4-4) iec1000-4-4 (previously 801-4) covers electrical fast-transient/ burst (eft) immunity. electrical fast transients occur as a result of arcing contacts in switches and relays. the tests simulate the interference generated when, for example, a power relay disconnects an inductive load. a spark is generated due to the well known back emf effect. in fact, the spark consists of a burst of sparks as the relay contacts separate. the voltage appearing on the line, therefore, consists of a burst of extremely fast transient impulses. a similar effect occurs when switching on fluorescent lights. the fast transient burst test, defined in iec1000-4-4, simulates this arcing and its waveform is illustrated in figure 23. it consists of a burst of 2.5 khz to 5 khz transients repeating at 300 ms intervals. it is specified for both power and data lines. four severity levels are defined in terms of an open-circuit voltage as a function of installation environment. the installa- tion environments are defined as 1. well-protected 2. protected 3. typical industrial 4. severe industrial 300ms 16ms v t v 0.2/0.4ms t 5ns 50ns figure 23. iec1000-4-4 fast transient waveform table v shows the peak voltages for each of the environments. table v. level v peak (kv) v peak (kv) psu i-o 1 0.5 0.25 2 1 0.5 32 1 44 2 a simplified circuit diagram of the actual eft generator is illustrated in figure 24. these transients are coupled onto the signal lines using an eft coupling clamp. the clamp is 1 m long and completely sur- rounds the cable, providing maximum coupling capacitance (50 pf to 200 pf typ) between the clamp and the cable. high energy transients are capacitively coupled onto the signal lines. fast rise times (5 ns) as specified by the standard result in very effective coupling. this test is very severe since high voltages are coupled onto the signal lines. the repetitive transients can often cause problems, where single pulses do not. destructive latchup may be induced due to the high energy content of the transients. note that this stress is applied while the interface products are powered up and are transmitting data. the eft test applies hundreds of pulses with higher energy than esd. worst case transient current on an i-o line can be as high as 40 a. high voltage source r c r m c c z s l c d 50 w output figure 24. eft generator test results are classified according to the following 1. normal performance within specification limits. 2. temporary degradation or loss of performance that is self- recoverable. 3. temporary degradation or loss of function or performance that requires operator intervention or system reset. 4. degradation or loss of function that is not recoverable due to damage.
C8C rev. 0 adm483e the adm483e has been tested under worst case conditions using unshielded cables, and meets classification 2 at severity level 4. data transmission during the transient condition is corrupted, but it may be resumed immediately following the eft event without user intervention. radiated immunity (iec1000-4-3) iec1000-4-3 (previously iec801-3) describes the measurement method and defines the levels of immunity to radiated electro- magnetic fields. it was originally intended to simulate the electro- magnetic fields generated by portable radio transceivers or any other device that gene rates continuous wave radiated electromag- netic energy. its scope has since been broadened to include spurious em energy, which can be radiated from fluorescent lights, thyristor drives, inductive loads, etc. testing for immunity involves irradiating the device with an em field. there are various methods of achieving this including use of anechoic chamber, stripline cell, tem cell and gtem cell. these consist essentially of two parallel plates with an electric field develo ped between them. the device under test is placed between the plates and exposed to the electric field. there are three severity levels having field strengths ranging from 1 v to 10 v/m. results are classified in a similar fashion to those for iec1000-4-2. 1. normal operation. 2. temporary degradation or loss of function that is self- recoverable when the interfering signal is removed. 3. temporary degradation or loss of function that requires operator intervention or system reset when the interfering signal is removed. 4. degradation or loss of function that is not recoverable due to damage. the adm483e comfortably meets classification 1 at the most stringent (level 3) requirement. in fact, field strengths up to 30 v/m showed no performance degradation and error-free data transmission continued even during irradiation. table vi. level field strength v/m 11 23 310 emi emissions the adm483e contains internal slew rate limiting in order to minimize the level of electromagnetic interference generated. figure 25 shows an fft plot when transmitting a 150 khz data stream. 10 0% 100 90 10db/div 500khz/div 0 5mhz figure 25. driver output waveform and fft plot trans- mitting @ 150 khz as may be seen, the slew limiting attenuates the high frequency components. emi is therefore reduced, as are reflections due to improperly terminated cables. en55022, cispr22 defines the permitted limits of radiated and conducted interference from information technology equipment (ite). the objective is to control the level of emissions, both con- ducted and radiated. for ease of measurement and analysis, conducted emissions are assumed to predominate below 30 mhz, while radiated emissions predominate above this frequency. conducted emissions this is a measure of noise that is conducted onto the mains power supply. the noise is measured using a lisn (linc impedance stabilizing network) and a spectrum analyzer. the test setup is illustrated in figure 26. the spectrum analyzer is set to scan the spectrum from 0 mhz to 30 mhz. figure 27 shows that the level of conducted emissions from the adm483e are well below the allowable limits. spectrum analyser dut lisn psu figure 26. conducted emissions test setup
adm483e C9C rev. 0 log frequency (0.15?0) ?mhz 0.3 0.6 1361030 80 0 70 40 30 20 10 60 50 limit db? figure 27. conducted emissions radiated emissions radiated emissions are measured at frequencies in excess of 30 mhz. a typical test setup for monitoring radiated emissions is illustrated in figure 28. out turntable radiated noise to receiver adjustable antenna figure 28. radiated emissions test setup figure 29 shows that the level of radiated emissions is also well below the allowable limit. limit 30 200 frequency ?mhz 80 70 60 50 40 30 20 10 0 db? figure 29. radiated emissions applications information differential data transmission differential data transmission is used to reliably transmit data at high rates over long distances and through noisy environments. differential transmission nullifies the effects of ground shifts and noise signals that appear as common-mode voltages on the line. th ere are two main standards approved by the electron- ics industries association (eia) that specify the electrical characteristics of transceivers used in differential data transmission. the rs-422 standard specifies data rates up to 10 mbaud and line lengths up to 4000 ft. a single driver can drive a transmis- sion line with up to 10 receivers. in order to cater for true multipoint communications, the rs- 485 standard was defined. this standard meets or exceeds all the requirements of rs-422, but also allows for up to 32 drivers and 32 receivers to be connected to a single bus. an extended common-mode range of C7 v to +12 v is defined. the most significant difference between rs-422 and rs-485 is the fact that the drivers may be disabled, thereby allowing more than one (32 in fact) to be connected to a single line. only one driver should be enabled at a time, but the rs-485 standard contains additional specifications to guarantee device safety in the event of line contention. cable and data rate the transmission line of choice for rs-485 communications is a twisted pair. twisted pair cable tends to cancel common-mode noise and also causes cancellation of the magnetic fields generated by the current flowing through each wire, thereby reducing the effective inductance of the pair. a typical application showing a multipoint transmission network is illustrated in figure 30. an rs-485 transmission line can have as many as 32 transceivers on the bus. only one driver can transmit at a particular time, but multiple receivers may be enabled simultaneously. rt rt d r d r d r r d figure 30. typical rs-485 network
C10C rev. 0 adm483e outline dimensions dimensions shown in inches and (mm). 8-lead soic (so-8) 0.1968 (5.00) 0.1890 (4.80) 8 5 4 1 0.2440 (6.20) 0.2284 (5.80) pin 1 0.1574 (4.00) 0.1497 (3.80) 0.0688 (1.75) 0.0532 (1.35) seating plane 0.0098 (0.25) 0.0040 (0.10) 0.0192 (0.49) 0.0138 (0.35) 0.0500 (1.27) bsc 0.0098 (0.25) 0.0075 (0.19) 0.0500 (1.27) 0.0160 (0.41) 8 0 0.0196 (0.50) 0.0099 (0.25) x 45 8-pin plastic dip (n-8) 8 14 5 0.430 (10.92) 0.348 (8.84) 0.280 (7.11) 0.240 (6.10) pin 1 seating plane 0.022 (0.558) 0.014 (0.356) 0.060 (1.52) 0.015 (0.38) 0.210 (5.33) max 0.130 (3.30) min 0.070 (1.77) 0.045 (1.15) 0.100 (2.54) bsc 0.160 (4.06) 0.115 (2.93) 0.325 (8.25) 0.300 (7.62) 0.015 (0.381) 0.008 (0.204) 0.195 (4.95) 0.115 (2.93)
C11C
C12C c2934C12C1/97 printed in u.s.a.

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