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for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim?s website at www.maxim integrated .com. general description the max481e, max483e, max485e, max487e?max491e, and max1487e are low-power transceivers for rs-485 and rs-422 communications in harsh environ- ments. each driver output and receiver input is protected against 15kv electro-static discharge (esd) shocks, without latchup. these parts contain one driver and one receiver. the max483e, max487e, max488e, and max489e feature reduced slew-rate drivers that minimize emi and reduce reflections caused by improperly termi- nated cables, thus allowing error-free data transmission up to 250kbps. the driver slew rates of the max481e, max485e, max490e, max491e, and max1487e are not limited, allowing them to transmit up to 2.5mbps. these transceivers draw as little as 120a supply cur- rent when unloaded or when fully loaded with disabled drivers (see selector guide ). additionally, the max481e, max483e, and max487e have a low-current shutdownmode in which they consume only 0.5a. all parts oper- ate from a single +5v supply. drivers are short-circuit current limited, and are protected against excessive power dissipation by thermal shutdown circuitry that places their outputs into a high-impedance state. the receiver input has a fail-safe feature that guar- antees a logic-high output if the input is open circuit. the max487e and max1487e feature quarter-unit-load receiver input impedance, allowing up to 128 trans- ceivers on the bus. the max488e?max491e are designed for full-duplex communications, while the max481e, max483e, max485e, max487e, and max1487e are designed for half-duplex applications. for applications that are not esd sensitive see the pin- and function-compatible max481, max483, max485, max487?max491, and max1487. applications low-power rs-485 transceiverslow-power rs-422 transceivers level translators transceivers for emi-sensitive applications industrial-control local area networks next-generation device features ? for fault-tolerant applications:max3430: 80v fault-protected, fail-safe, 1/4- unit load, +3.3v, rs-485 transceiver max3080?max3089: fail-safe, high-speed (10mbps), slew-rate-limited, rs-485/rs-422 transceivers ? for space-constrained applications:max3460?max3464: +5v, fail-safe, 20mbps, profibus, rs-485/rs-422 transceivers max3362: +3.3v, high-speed, rs-485/rs-422 transceiver in a sot23 package max3280e?max3284e: 15kv esd-protected, 52mbps, +3v to +5.5v, sot23, rs-485/rs-422 true fail-safe receivers max3030e?max3033e: 15kv esd-protected, +3.3v, quad rs-422 transmitters ? for multiple transceiver applications:max3293/max3294/max3295: 20mbps, +3.3v, sot23, rs-485/rs-422 transmitters ? for fail-safe applications:max3440e?max3444e: 15kv esd-protected, 60v fault-protected, 10mbps, fail-safe rs-485/j1708 transceivers ? for low-voltage applications:max3483e/max3485e/max3486e/max3488e/ max3490e/max3491e: +3.3v powered, 15kv esd-protected, 12mbps, slew-rate-limited, true rs-485/rs-422 transceivers 15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers ordering information part temp range pin-package max481e cpa 0c to +70c 8 plastic dip max481ecsa 0c to +70c 8 so max481eepa -40c to +85c 8 plastic dip max481eesa -40c to +85c 8 so max483e cpa 0c to +70c 8 plastic dip max483ecsa 0c to +70c 8 so max483eepa -40c to +85c 8 plastic dip max483eesa -40c to +85c 8 so ordering information continued at end of data sheet.selector guide appears at end of data sheet . 19-0410; rev 4; 10/03 max481e/max483e/max485e/ max487eCmax491e/max1487e downloaded from: http:/// available
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers supply voltage (v cc ) .............................................................12v control input voltage ( ?r ? e ? , de)...................-0.5v to (v cc + 0.5v) driver input voltage (di).............................-0.5v to (v cc + 0.5v) driver output voltage (y, z; a, b) ..........................-8v to +12.5v receiver input voltage (a, b).................................-8v to +12.5v receiver output voltage (ro)....................-0.5v to (v cc + 0.5v) continuous power dissipation (t a = +70c) 8-pin plastic dip (derate 9.09mw/c above +70c) ....727mw 14-pin plastic dip (derate 10.00mw/c above +70c) ..800mw 8-pin so (derate 5.88mw/c above +70c).................471mw 14-pin so (derate 8.33mw/c above +70c)...............667mw operating temperature ranges max4_ _c_ _/max1487ec_ a .............................0c to +70c max4_ _e_ _/max1487ee_ a...........................-40c to +85c storage temperature range .............................-65c to +160c lead temperature (soldering, 10sec) .............................+300c dc electrical characteristics(v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. absolute maximum ratings parameter symbol min typ max units driver common-mode outputvoltage v oc 3 v change in magnitude of driverdifferential output voltage for complementary output states v od 0.2 v change in magnitude of drivercommon-mode output voltage for complementary output states v od 0.2 v input high voltage v ih 2.0 v input low voltage v il 0.8 v input current i in1 2 a differential driver output (no load) v od1 5 v 2 v differential driver output(with load) v od2 1.5 5 1.0 -0.8 ma 0.25 ma -0.2 receiver differential thresholdvoltage -0.2 0.2 v receiver input hysteresis v th 70 mv receiver output high voltage v oh 3.5 receiver output low voltage v ol 0.4 v three-state (high impedance)output current at receiver i ozr 1 a 12 k conditions de = 0v;v cc = 0v or 5.25v, all devices exceptmax487e/max1487e r = 27 or 50 , figure 8 r = 27 or 50 , figure 8 r = 27 or 50 , figure 8 de, di, ?r ? e ? max487e/max1487e,de = 0v, v cc = 0v or 5.25v de, di, ?r ? e ? de, di, ?r ? e ? -7v v cm 12v v cm = 0v i o = -4ma, v id = 200mv i o = 4ma, v id = -200mv r = 50 (rs-422) 0.4v v o 2.4v r = 27 (rs-485), figure 8 -7v v cm 12v, all devices except max487e/max1487e receiver input resistance r in -7v v cm 12v, max487e/max1487e 48 k v th i in2 input current(a, b) v in = 12v v in = -7v v in = 12v v in = -7v v max481e/max483e/max485e/ max487eCmax491e/max1487e 2 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers switching characteristics?max481e/max485e, max490e/max491e, max1487e(v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) dc electrical characteristics (continued)(v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) ma 79 5 0v v o v cc i osr receiver short-circuit current ma 35 250 -7v v o 12v (note 4) i osd2 driver short-circuit current,v o = low ma 35 250 -7v v o 12v (note 4) i osd1 driver short-circuit current,v o = high max1487e,? r ? e ? = 0v or v cc 250 400 350 650 conditions units min typ max symbol parameter 230 400 300 500 max481e/max485e,? r ? e ? = 0v or v cc 500 900 max490e/max491e,de, di, ? r ? e ? = 0v or v cc 300 500 max488e/max489e,de, di, ? r ? e ? = 0v or v cc 120 250 de = v cc 300 500 de = 0v de = v cc de = 0v a max481e/483e/487e, de = 0v, ?r ? e ? = v cc 0.5 10 i shdn supply current in shutdown 120 250 i cc no-load supply current(note 3) de = v cc de = 0v max483e max487e max483e/max487e,? r ? e ? = 0v or v cc a 52 02 5 max490ec/e, max491ec/e max481e, max485e, max1487e driver rise or fall time t r , t f 32 04 0 figures 10 and 12,r diff = 54 , c l1 = c l2 = 100pf max490ec/e, max491ec/e figures 11 and 13, c l = 15pf, s2 closed figures 11 and 13, c l = 15pf, s1 closed figures 11 and 13, c l = 100pf, s1 closed figures 11 and 13, c l = 100pf, s2 closed parameter symbol min typ max units driver enable to output high t zh 45 70 receiver input to output t plh , t phl driver output skew to output ns driver enable to output low t zl 45 70 ns driver disable time from low t lz 45 70 ns | t plh - t phl | differential receiver skew driver disable time from high t skd t hz 45 70 5 ns 20 60 200 receiver enable to output low t zl 20 50 ns receiver enable to output high driver input to output t zh 20 50 ns receiver disable time from low t lz 20 50 t plh 10 40 60 ns receiver disable time from high t hz 20 50 mbps maximum data rate f max 2.5 ns time to shutdown t shdn 50 200 600 t skew 51 0 ns conditions figures 10 and 14,r diff = 54 , c l1 = c l2 = 100pf figures 10 and 14, r diff = 54 , c l1 = c l2 = 100pf figures 9 and 15, c rl = 15pf, s1 closed figures 9 and 15, c rl = 15pf, s2 closed figures 9 and 15, c rl = 15pf, s1 closed figures 9 and 15, c rl = 15pf, s2 closed max481e (note 5) figures 10 and 12, r diff = 54 , c l1 = c l2 = 100pf max481e, max485e, max1487e ns figures 10 and 12, r diff = 54 , c l1 = c l2 = 100pf t phl 10 40 60 ns ns ns 20 60 150 ns kv 15 a, b, y and z pins, tested using human body model esd protection max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 3 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers switching characteristics?max483e, max487e/max488e/max489e(v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) switching characteristics? max481e/max485e, max490e/max491e, max1487e (continued) (v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) 225 1000 figures 11 and 13, c l = 100pf, s2 closed figures 11 and 13, c l = 100pf, s1 closed figures 9 and 15, c l = 15pf, s2 closed, a - b = 2v conditions ns 45 100 t zh(shdn) driver enable from shutdown tooutput high (max481e) ns figures 9 and 15, c l = 15pf, s1 closed, b - a = 2v t zl(shdn) receiver enable from shutdownto output low (max481e) ns 45 100 t zl(shdn) driver enable from shutdown tooutput low (max481e) ns 225 1000 t zh(shdn) receiver enable from shutdownto output high (max481e) units min typ max symbol parameter t plh t skew figures 10 and 12, r diff = 54 , c l1 = c l2 = 100pf t phl figures 10 and 12, r diff = 54 , c l1 = c l2 = 100pf driver input to output driver output skew to output ns 20 800 ns ns 2000 max483e/max487e, figures 11 and 13,c l = 100pf, s2 closed t zh(shdn) driver enable from shutdown tooutput high 250 2000 ns 2500 max483e/max487e, figures 9 and 15, c l = 15pf, s1 closed t zl(shdn) receiver enable from shutdownto output low ns 2500 max483e/max487e, figures 9 and 15, c l = 15pf, s2 closed t zh(shdn) receiver enable from shutdownto output high ns 2000 max483e/max487e, figures 11 and 13,c l = 100pf, s1 closed t zl(shdn) driver enable from shutdown tooutput low ns 50 200 600 max483e/max487e (note 5) t shdn time to shutdown t phl t plh , t phl < 50% of data period figures 9 and 15, c rl = 15pf, s2 closed figures 9 and 15, c rl = 15pf, s1 closed figures 9 and 15, c rl = 15pf, s2 closed figures 9 and 15, c rl = 15pf, s1 closed figures 11 and 13, c l = 15pf, s2 closed figures 10 and 14, r diff = 54 , c l1 = c l2 = 100pf figures 11 and 13, c l = 15pf, s1 closed figures 11 and 13, c l = 100pf, s1 closed figures 11 and 13, c l = 100pf, s2 closed conditions kbps 250 f max 250 800 2000 maximum data rate ns 25 50 t hz receiver disable time from high ns 250 800 2000 25 50 t lz receiver disable time from low ns 25 50 t zh receiver enable to output high ns 25 50 t zl receiver enable to output low ns ns 100 300 3000 t hz t skd driver disable time from high i t plh - t phl i differential receiver skew figures 10 and 14, r diff = 54 , c l1 = c l2 = 100pf ns 300 3000 t lz driver disable time from low ns 250 2000 t zl driver enable to output low ns figures 10 and 12, r diff = 54 , c l1 = c l2 = 100pf ns 250 2000 t r , t f 250 2000 driver rise or fall time ns t plh receiver input to output 250 2000 t zh driver enable to output high units min typ max symbol parameter max481e/max483e/max485e/ max487eCmax491e/max1487e 4 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers 0 5 10 15 20 25 30 35 40 45 50 output current vs. receiver output low voltage max481e-01 output low voltage (v) output current (ma) 1.5 2.0 2.5 1.0 0.5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -60 -20 60 receiver output low voltage vs. temperature max481e-04 temperature (c) output low voltage (v) 20 100 -40 40 08 0 i ro = 8ma 0 -5 -10 -15 -20 -25 1.5 3.0 output current vs. receiver output high voltage max481e-02 output high voltage (v) output current (ma) 5.0 4.5 4.0 2.0 2.5 3.5 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 -60 -20 60 receiver output high voltage vs. temperature max481e-03 temperature (c) output high voltage (v) 20 100 -40 40 08 0 i ro = 8ma 0 10 20 30 40 50 60 70 80 90 driver output current vs. differential output voltage max481e-05 differential output voltage (v) output current (ma) 1.5 2.0 2.5 3.0 3.5 4.0 4.5 1.0 0.5 0 __________________________________________typical operating characteristics (v cc = 5v, t a = +25c, unless otherwise noted.) notes for electrical/switching characteristics note 1: all currents into device pins are positive; all currents out of device pins are negative. all voltages are referenced to device ground unless otherwise specified. note 2: all typical specifications are given for v cc = 5v and t a = +25c. note 3: supply current specification is valid for loaded transmitters when de = 0v. note 4: applies to peak current. see typical operating characteristics. note 5: the max481e/max483e/max487e are put into shutdown by bringing ? r ? e ? high and de low. if the inputs are in this state for less than 50ns, the parts are guaranteed not to enter shutdown. if the inputs are in this state for at least 600ns, the parts areguaranteed to have entered shutdown. see low-power shutdown mode section. max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 5 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers ____________________________typical operating characteristics (continued) (v cc = 5v, t a = +25c, unless otherwise noted.) 1.5 2.32.2 2.1 2.0 1.9 1.8 1.7 1.6 -60 -20 60 driver differential output voltage vs. temperature max481e-06 temperature (c) differential output voltage (v) 20 100 -40 40 08 0 r = 54 0 20 40 60 80 100 120 140 output current vs. driver output low voltage max481e-07 output low voltage (v) output current (ma) 024681 01 2 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -8 -2 output current vs. driver output high voltage max481e-08 output high voltage (v) output current (ma) 6 4 2 -6 -4 0 0 100 200 300 400 500 600 -60 -20 60 max481e/max485e/max490e/max491e supply current vs. temperature max481e-09 temperature (c) supply current ( a) 20 100 -40 40 08 0 max481e/max485e; de = v cc , re = x max485e; de = 0, re = x,max481e; de = re = 0 max490e/max491e; de = re = x max481e; de = 0, re = v cc 0 100 200 300 400 500 600 -60 -20 60 max483e/max487e?max489e supply current vs. temperature max481e-10 temperature (c) supply current ( a) 20 100 -40 40 08 0 max483e; de = v cc , re = x max487e; de = v cc , re = x max483e/max487e; de = 0, re = v cc max483e/max487e; de = re = 0,max488e/max489e; de = re = x 0 100 200 300 400 500 600 -60 -20 60 max1487e supply current vs. temperature max481e-11 temperature (c) supply current ( a) 20 100 -40 40 08 0 max1487e; de = v cc , re = x max1487e; de = 0v, re = x max481e/max483e/max485e/ max487eCmax491e/max1487e 6 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers ______________________________________________________________pin description 1 2 receiver output: if a > b by 200mv, ro will be high;if a < b by 200mv, ro will be low. 2 ? receiver output enable. ro is enabled when ?r ? e ? is low; ro is high impedance when ? r ? e ? is high. 3 ? driver output enable. the driver outputs, y and z, are enabled by bringing de high. they are high imped- ance when de is low. if the driver outputs are enabled, the parts function as line drivers. while they are high impedance, they function as line receivers if ? r ? e ? is low. 4 3 driver input. a low on di forces output y low and out-put z high. similarly, a high on di forces output y high and output z low. 6 ? noninverting receiver input and noninverting driveroutput ? 6 inverting driver output ? 5 noninverting driver output 5 4 ground ? ? no connect?not internally connected 8 1 positive supply: 4.75v v cc 5.25v ? 7 inverting receiver input 7 ? inverting receiver input and inverting driver output ? 8 noninverting receiver input pin 2 3 4 5 ? 10 9 6, 7 1, 8, 13 14 11 ? 12 ro ?r ? e ? de di a z y gnd n.c. v cc b b a function max489emax491e name max488emax490e max481e/max483emax485e/max487e max1487e max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 7 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers max488e max490e top view 12 3 4 ro di gnd 87 6 5 ab z y v cc dip/so r d rt rt v cc 56 7 8 rodi gnd 4 gnd di ro 3 2 a b yz v cc dr r d 1 0.1 f note: typical operating circuit shown with dip/so package. max489e max491e dip/so top view rt rt de v cc re gnd v cc re gnd de rodi 910 1211 b a z y 0.1 f 5 ro nc di 2 1, 8, 13 3 6, 7 14 4 1 2 3 4 5 6 7 14 13 12 11 10 9 8 v cc n.c.n.c. ab z y n.c. ro re de di gndgnd r d d rd r figure 2. max488e/max490e pin configuration and typical operating circuit figure 3. max489e/max491e pin configuration and typical operating circuit max481e max483e max485e max487e max1487e top view note: pin labels y and z on timing, test, and waveform diagrams refer to pins a and b when de is high. typical operating circuit shown with dip/so package. 12 3 4 85 v cc 0.1 f gnd di de re ro r d rt rt 76 d r de re di ro a b 12 3 4 87 6 5 v cc ba gnd di de re ro dip/so r d b a figure 1. max481e/max483e/max485e/max487e/max1487e pin configuration and typical operating circuit max481e/max483e/max485e/ max487eCmax491e/max1487e 8 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers __________function tables (max481e/max483e/max485e/max487e/max1487e) table 1. transmitting table 2. receiving inputs output re de a-b ro 00 0 1 00 0 0 > +0.2v < -0.2v inputs open x 10 1 high-z * x = don't carehigh-z = high impedance * shutdown mode for max481e/max483e/max487e inputs outputs re de di z y xx 01 11 0 0 10 xx 01 high-z high-z * 10 high-z high-z * x = don't carehigh-z = high impedance * shutdown mode for max481e/max483e/max487e __________applications information the max481e/max483e/max485e/max487e?max491eand max1487e are low-power transceivers for rs-485 and rs-422 communications. these ?e? versions of the max481, max483, max485, max487?max491, and max1487 provide extra protection against esd. the rugged max481e, max483e, max485e, max497e? max491e, and max1487e are intended for harsh envi- ronments where high-speed communication is important. these devices eliminate the need for transient suppres- sor diodes and the associated high capacitance loading. the standard (non-?e?) max481, max483, max485, max487?max491, and max1487 are recommended for applications where cost is critical. the max481e, max485e, max490e, max491e, and max1487e can transmit and receive at data rates up to 2.5mbps, while the max483e, max487e, max488e, and max489e are specified for data rates up to 250kbps. the max488e?max491e are full-duplex transceivers, while the max481e, max483e, max487e, and max1487e are half-duplex. in addition, driver- enable (de) and receiver-enable (re) pins are included on the max481e, max483e, max485e, max487e, max489e, max491e, and max1487e. when disabled, the driver and receiver outputs are high impedance. 15kv esd protection as with all maxim devices, esd-protection structuresare incorporated on all pins to protect against electro- static discharges encountered during handling and assembly. the driver outputs and receiver inputs have extra protection against static electricity. maxim?s engi- neers developed state-of-the-art structures to protect these pins against esd of 15kv without damage. the esd structures withstand high esd in all states: normal operation, shutdown, and powered down. after an esd event, maxim?s max481e, max483e, max485e, max487e?max491e, and max1487e keep working without latchup. esd protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to 15kv using the human body model. other esd test methodologies include iec10004-2 con- tact discharge and iec1000-4-2 air-gap discharge (for- merly iec801-2). esd test conditions esd performance depends on a variety of conditions.contact maxim for a reliability report that documents test set-up, test methodology, and test results. human body model figure 4 shows the human body model, and figure 5 shows the current waveform it generates when dis- charged into a low impedance. this model consists of a 100pf capacitor charged to the esd voltage of inter- est, which is then discharged into the test device through a 1.5k resistor. iec1000-4-2 the iec1000-4-2 standard covers esd testing and per-formance of finished equipment; it does not specifically refer to integrated circuits (figure 6). max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 9 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers charge current limit resistor discharge resistance storagecapacitor c s 150pf r c 50m to 100m r d 330 high- voltage dc source device under test figure 6. iec1000-4-2 esd test model t r = 0.7ns to 1ns 30ns 60ns t 100% 90%10% i peak i rr y z v od v oc figure 8. driver dc test load figure 7. iec1000-4-2 esd generator current waveform receiver output test point 1k 1k s1 s2 v cc c rl 15pf figure 9. receiver timing test load charge current limit resistor discharge resistance storagecapacitor c s 100pf r c 1m r d 1500 high voltage dc source device under test figure 4. human body esd test model i p 100% 90% 36.8% t rl time t dl current waveform peak-to-peak ringing(not drawn to scale) i r 10% 0 0 amperes figure 5. human body model current waveform max481e/max483e/max485e/ max487eCmax491e/max1487e 10 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers di de 3v y z c l1 c l2 ab ro re r diff v id output under test 500 s1s2 v cc c l figure 10. driver/receiver timing test circuit figure 11. driver timing test load di 3v0v z y v o 0v -v o v o 1.5v t plh 1/2 v o 10% t r 90% 90% t phl 1.5v 1/2 v o 10% t f v diff = v (y) - v (z) v diff t skew = | t plh - t phl | output normally low output normally high 3v 0v y, z v ol y, z 0v 1.5v 1.5v v ol +0.5v v oh -0.5v 2.3v 2.3v t zl(shdn) , t zl t lz t zh(shdn) , t zh t hz de figure 12. driver propagation delays figure 13. driver enable and disable times (except max488e and max490e) v oh v ol v id -v id 1.5v 0v 1.5v output input 0v roa-b t plh t phl output normally low output normally high 3v0v v cc roro 0v 1.5v 1.5v v ol + 0.5v v oh - 0.5v 1.5v 1.5v t zl(shdn) , t zl t lz t zh(shdn) , t zh t hz re figure 14. receiver propagation delays f igure 15. receiver enable and disable times (except max488e and max490e) max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 11 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers the major difference between tests done using thehuman body model and iec1000-4-2 is higher peak current in iec1000-4-2, because series resistance is lower in the iec1000-4-2 model. hence, the esd with- stand voltage measured to iec1000-4-2 is generally lower than that measured using the human body model. figure 7 shows the current waveform for the 8kv iec1000-4-2 esd contact-discharge test. the air-gap test involves approaching the device with a charged probe. the contact-discharge method connects the probe to the device before the probe is energized. machine model the machine model for esd tests all pins using a 200pf storage capacitor and zero discharge resis- tance. its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. of course, all pins require this protec- tion during manufacturing?not just inputs and outputs. therefore, after pc board assembly, the machine model is less relevant to i/o ports. max487e/max1487e: 128 transceivers on the bus the 48k , 1/4-unit-load receiver input impedance of the max487e and max1487e allows up to 128 transceiverson a bus, compared to the 1-unit load (12k input impedance) of standard rs-485 drivers (32 transceiversmaximum). any combination of max487e/max1487e and other rs-485 transceivers with a total of 32 unit loads or less can be put on the bus. the max481e, max483e, max485e, and max488e?max491e have standard 12k receiver input impedance. max483e/max487e/max488e/max489e: reduced emi and reflections the max483e and max487e?max489e are slew-ratelimited, minimizing emi and reducing reflections caused by improperly terminated cables. figure 16 shows the driver output waveform and its fourier analy- sis of a 150khz signal transmitted by a max481e, max485e, max490e, max491e, or max1487e. high- frequency harmonics with large amplitudes are evident. figure 17 shows the same information displayed for a max483e, max487e, max488e, or max489e transmit- ting under the same conditions. figure 17?s high-fre- quency harmonics have much lower amplitudes, and the potential for emi is significantly reduced. low-power shutdown mode (max481e/max483e/max487e) a low-power shutdown mode is initiated by bringing both re high and de low. the devices will not shut down unless both the driver and receiver are disabled. in shutdown, the devices typically draw only 0.5a of supply current. re and de may be driven simultaneously; the parts are guaranteed not to enter shutdown if re is high and de is low for less than 50ns. if the inputs are in this statefor at least 600ns, the parts are guaranteed to enter shutdown. for the max481e, max483e, and max487e, the t zh and t zl enable times assume the part was not in the low-power shutdown state (the max485e, max488e?max491e, and max1487e can not be shut down). the t zh(shdn) and t zl(shdn) enable times assume the parts were shut down (see electrical characteristics ). 500khz/div 0hz 5mhz 10db/div figure 16. driver output waveform and fft plot of max485e/max490e/max491e/max1487e transmitting a 150khz signal 500khz/div 0hz 5mhz 10db/div figure 17. driver output waveform and fft plot of max483e/max487e?max489e transmitting a 150khz signal max481e/max483e/max485e/ max487eCmax491e/max1487e 12 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers it takes the drivers and receivers longer to becomeenabled from the low-power shutdown state (t zh(shdn ) , t zl(shdn) ) than from the operating mode (t zh , t zl ). (the parts are in operating mode if the re , de inputs equal a logical 0,1 or 1,1 or 0, 0.) driver output protection excessive output current and power dissipation causedby faults or by bus contention are prevented by two mechanisms. a foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see typical operating characteristics ). in addition, a thermal shut- down circuit forces the driver outputs into a high-imped- ance state if the die temperature rises excessively. propagation delay many digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. typical propagation delays are shown infigures 19?22 using figure 18?s test circuit. the difference in receiver delay times, t plh - t phl , is typically under 13ns for the max481e, max485e,max490e, max491e, and max1487e, and is typically less than 100ns for the max483e and max487e? max489e. the driver skew times are typically 5ns (10ns max) for the max481e, max485e, max490e, max491e, and max1487e, and are typically 100ns (800ns max) for the max483e and max487e?max489e. typical applications the max481e, max483e, max485e, max487e?max491e, and max1487e transceivers are designed for bidirectional data communications on multipoint bus transmission lines. figures 25 and 26 show typical net- work application circuits. these parts can also be used as line repeaters, with cable lengths longer than 4000 feet. to minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possi- ble. the slew-rate-limited max483e and max487e? max489e are more tolerant of imperfect termination. bypass the v cc pin with 0.1f. isolated rs-485 for isolated rs-485 applications, see the max253 andmax1480 data sheets. line length vs. data rate the rs-485/rs-422 standard covers line lengths up to4000 feet. figures 23 and 24 show the system differen- tial voltage for the parts driving 4000 feet of 26awg twisted-pair wire at 110khz into 100 loads. 100pf100pf r = 54 a b y d z r receiverout ttl in t r , t f < 6ns figure 18. receiver propagation delay test circuit max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 13 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers 25ns/div 5v/div ro b a 500mv/div figure 19. max481e/max485e/max490e/max1487e receiver t phl 25ns/div 5v/div ro ba 500mv/div figure 20. max481e/max485e/max490e/max491e/ max1487e receiver t plh 200ns/div 5v/div ro b a 500mv/div figure 21. max483e/max487e?max489e receiver t phl 200ns/div 5v/div ro b a 500mv/div figure 22. max483e/max487e?max489e receiver t plh 2 s/div do 0v 0v5v 5v-1v 0 di v a - v b figure 23. max481e/max485e/max490e/max491e/ max1487e system differential voltage at 110khz driving 4000ft of cable 2 s/div do 0v 0v5v 5v-1v 1v0 di v b - v a figure 24. max483e/max1487e?max489e system differential voltage at 110khz driving 4000ft of cable max481e/max483e/max485e/ max487eCmax491e/max1487e 14 maxim integrated downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers figure 26. max488e?max491e full-duplex rs-485 network 120 120 r d ro re de di ab y 120 120 di di di ro ro ro de de de re re re z z z z y y y aa a bb b d d d r r r max488e max489e max490e max491e note: re and de on max489e/max491e only. di ro de re a b re re re ro ro ro di di di de de de d d d r r r b b b a a a 120 120 d r max481e max483e max485e max487e max1487e figure 25. max481e/max483e/max485e/max487e/max1487e typical half-duplex rs-485 network max481e/max483e/max485e/ max487eCmax491e/max1487e maxim integrated 15 downloaded from: http:///
15kv esd-protected, slew-rate-limited, low-power, rs-485/rs-422 transceivers package infor mation for the latest package outline information, go to www.maxim-ic.com/packages . ordering information (continued) part temp range pin-package max485e cpa 0c to +70c 8 plastic dip max485ecsa 0c to +70c 8 so max485eepa -40c to +85c 8 plastic dip max485eesa -40c to +85c 8 so max487e cpa 0c to +70c 8 plastic dip max487ecsa 0c to +70c 8 so max487eepa -40c to +85c 8 plastic dip max487eesa -40c to +85c 8 so max488e cpa 0c to +70c 8 plastic dip max488ecsa 0c to +70c 8 so max488eepa -40c to +85c 8 plastic dip max488eesa -40c to +85c 8 so max489e cpd 0c to +70c 14 plastic dip max489ecsd 0c to +70c 14 so part temp range pin-package max489eepd -40c to +85c 14 plastic dip max489eesd -40c to +85c 14 so max490e cpa 0c to +70c 8 plastic dip max490ecsa 0c to +70c 8 so max490eepa -40c to +85c 8 plastic dip max490eesa -40c to +85c 8 so max491e cpd 0c to +70c 14 plastic dip max491ecsd 0c to +70c 14 so max491eepd -40c to +85c 14 plastic dip max491eesd -40c to +85c 14 so max1487e cpa 0c to +70c 8 plastic dip max1487ecsa 0c to +70c 8 so max1487eepa -40c to +85c 8 plastic dip max1487eesa -40c to +85c 8 so part number half/full duplex data rate (mbps) slew- rate limited low-power shutdown receiver/ driver enable quiescent current ( a) number of transmitters on bus pin count max481e half 2.5 no yes yes 300 32 8 max483e half 0.25 yes yes yes 120 32 8 max485e half 2.5 no no yes 300 32 8 max487e half 0.25 yes yes yes 120 128 8 max488e full 0.25 yes no no 120 32 8 max489e full 0.25 yes no yes 120 32 14 max490e full 2.5 no no no 300 32 8 max491e full 2.5 no no yes 300 32 14 max1487e half 2.5 no no yes 230 128 8 selector guide chip information transistor count: 295 max481e/max483e/max485e/ max487eCmax491e/max1487e 16 maxim integrated 160 rio robles, san jose, ca 95134 usa 1-408-601-1000 maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. ? 2003 maxim integrated the maxim logo and maxim integrated are trademarks of maxim integrated products, inc. downloaded from: http:///

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