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_________________ general description the MAX1480Ea/MAX1480Ec/max1490ea/max1490eb are complete, electrically isolated, rs-485/rs-422 data communications interface solutions in a hybrid microcir- cuit. the rs-485/rs-422 i/o pins are protected against ?5kv electrostatic discharge (esd) shocks, without latchup. transceivers, optocouplers, and a transformer provide a complete interface in a standard dip package. a single +5v supply on the logic side powers both sides of the interface. the MAX1480Ec/max1490eb feature reduced-slew-rate drivers that minimize emi and reduce reflections caused by improperly terminated cables, allowing error-free data transmission at data rates up to 160kbps. the MAX1480Ea/max1490ea driver slew rate is not limited, allowing transmission rates up to 2.5mbps. the MAX1480Ea/MAX1480Ec are designed for half-duplex communication, while the max1490ea/max1490eb fea- ture full-duplex communication. drivers are short-circuit current limited and protected against excessive power dissipation by thermal shut- down circuitry that places the driver outputs into a high- impedance state. the receiver input has a fail-safe feature that guarantees a known output ( ro low for the MAX1480Ea/MAX1480Ec, ro high for the max1490ea/ max1490eb) if the input is open circuit. the MAX1480Ea/MAX1480Ec/max1490ea/max1490eb withstand 1260v rms (1min) or 1520v rms (1s). their iso- lated outputs meet all rs-485/rs-422 specifications. the MAX1480Ea/MAX1480Ec are available in a 28-pin dip package, and the max1490ea/max1490eb are available in a 24-pin dip package. . ________________________applications isolated rs-485/rs-422 data interface transceivers for emi-sensitive applications industrial-control local area networks automatic test equipment hvac/building control networks telecom ____________________________features isolated data interface, guaranteed to 1260v rms (1min) 15kv esd protection on i/o pins slew-rate limited for errorless data transmission (MAX1480Ec/max1490eb) high-speed, isolated, 2.5mbps rs-485/rs-422 interface (MAX1480Ea/max1490ea) full-duplex data communication (max1490ea/max1490eb) single +5v supply current limiting and thermal shutdown for driver overload protection standard 0.6in dip packages 28-pin dip (MAX1480Ea/MAX1480Ec) 24-pin dip (max1490ea/max1490eb) MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces ________________________________________________________________ maxim integrated products 1 pin configurations 1 24 23 22 21 20 19 18 17 2 3 4 5 6 7 8 ac1 ac2 iso v cc1 iso ro drv d2 d1 a b z y sd fs gnd1 16 15 14 13 9 10 11 12 iso com1 iso di drv iso v cc2 iso ro led gnd2 ro di dip v cc2 v cc3 v cc4 v cc1 max1490ea/ max1490eb max845e max488e max490e top view isolation barrier 19-1940; rev 0; 4/01 part ? MAX1480Ea cpi MAX1480Eaepi -40? to +85? 0? to +70? temp. range pin-package 28 wide plastic dip* 28 wide plastic dip* _______________ordering information ordering information continued at end of data sheet. ? data rate for a parts is up to 2.5mbps. data rate for c parts is up to 250kbps. *see reliability section at end of data sheet. pin configurations continued at end of data sheet. selector guide appears at end of data sheet. for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com.
ma MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc_ = +5v ?0%, v fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = +5v and t a = +25?.) (notes 1, 2) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. with respect to gnd_ supply voltage (v cc_ )..........................................-0.3v to +6v control input voltage (sd, fs)..............-0.3v to (v cc_ + 0.3v) receiver output voltage (ro, ro).......-0.3v to (v cc_ + 0.3v) output switch voltage (d1, d2).......................................+12v with respect to iso com_ control input voltage (iso de_) ....-0.3v to (iso v cc_ + 0.3v) driver input voltage (iso di_) .......-0.3v to (iso v cc_ + 0.3v) receiver output voltage (iso ro_) ..-0.3v to (iso v cc_ + 0.3v) driver output voltage (a, b, y, z) ......................-8v to +12.5v receiver input voltage (a, b).............................-8v to +12.5v led forward current (di, de, iso ro led) ......................50ma continuous power dissipation (t a = +70?) 24-pin plastic dip (derate 8.7mw? above +70?) ....696mw 28-pin plastic dip (derate 9.09mw/? above +70?) .727mw operating temperature ranges MAX1480E_cpi/max1490e_cpi ........................0? to +70? MAX1480E_epi/max1490e_epi ......................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? operating supply current i cc 1.5 5 r = 27 ? (rs-485), figure 4 r = 50 ? (rs-422) v 2 v od2 differential driver output (with load) v fs = 0 conditions 535 f swl units min typ max symbol parameter fs = v cc_ or open 725 f swh 85 120 55 120 MAX1480Ea, de = v cc_ or open 145 130 low v 0.8 v sdl MAX1480Ec, de = v cc_ or open shutdown input threshold sd = v cc_ high ? 0.2 i shdn shutdown supply current (note 3) 2.4 v sdh 120 65 125 high low 2.4 v fsh v 0.8 v fsl fs input threshold de , di , figures 1 and 2 de , di , figures 1 and 2 v v cc - 0.4 v ih input high voltage v 0.4 v il input low voltage fs low fs high ? 50 fs input pullup current pa 10 fs input leakage current pa 10 shutdown input leakage current r l = r l = 54 ? r l = r l = 54 ? r l = max1490eb r l = 54 ? t a = +25?, f = 1mhz pf 10 c iso isolation capacitance t a = +25?, v iso = 50vdc m ? 100 10,000 r iso isolation resistance khz switch frequency ma r l = r l = 54 ? 130 180 max1490ea 180 v 8 v od1 differential driver output (no load) t a = +25?, 1min (note 4) v rms 1260 v iso isolation voltage
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc_ = +5v ?0%, v fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = +5v and t a = +25?.) (notes 1, 2) switching characteristics?ax1480ea/max1490ea (v cc_ = +5v ?0%, v fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = +5v and t a = +25?.) driver disable time from low (MAX1480Ea only) t lz 0.5 1.8 ? figures 6 and 8, c l = 15pf, s1 closed driver disable time from high (MAX1480Ea only) t hz 0.5 1.8 ? figures 6 and 8, c l = 15pf, s2 closed driver enable to output low (MAX1480Ea only) t zl 1.0 1.8 ? figures 6 and 8, c l = 100pf, s1 closed parameter symbol min typ max units driver rise or fall time t r, t f 15 50 ns receiver input to output propagation delay t phl 90 225 ns figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf t plh 120 225 driver enable to output high (MAX1480Ea only) t zh 1.0 1.8 ? figures 5 and 10, r diff = 54 ? , c l1 = c l2 = 100pf figures 6 and 8, c l = 100pf, s2 closed t plh 90 275 figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf driver output skew conditions t skew 30 100 ns driver input to output propagation delay t phl 60 275 ns figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf -7v v cm +12v v v th receiver differential threshold a, b, y, and z pins, tested using human body model, figures 1 and 2 kv iso i osd esd protection r = 27 ? or 50 ? , figure 4 v 0.3 ? v od conditions change in magnitude of driver output voltage for complementary output states ma 0.25 r = 27 ? or 50 ? , figure 4 v cm = 0 k ? r in receiver input resistance mv ? v th receiver input hysteresis v 4 v oc driver common-mode output 1.0 units min typ max symbol parameter v out = 5.5v ? i oh receiver output high current using resistor values listed in tables 1 and 2 -7v v o 12v (note 5) ma iso i osd driver short-circuit current v v ol receiver output low voltage differential common mode 0.3 max1490ea/ max1490eb MAX1480Ea/ MAX1480Ec MAX1480Ea/ MAX1480Ec max1490ea/ max1490eb 0.2 iso i in input current (a, b) 0.8 de = 0, v cc_ = 0 or +5.5v v in = +12v v in = -7v 12 -0.2 0.2 70 0.4 250 100 ?5 -7v v cm +12v 48 (max1490e_) (MAX1480E_)
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 4 _______________________________________________________________________________________ note 1: all currents into device pins are positive; all currents out of device pins are negative. all voltages are referenced to logic- side ground (gnd_), unless otherwise specified. note 2: for de and di pin descriptions, see detailed block diagram and typical application circuit (figure 1 for MAX1480Ea/ MAX1480Ec, figure 2 for max1490ea/max1490eb). note 3: shutdown supply current is the current at v cc1 and v cc2 when shutdown is enabled. note 4: limit guaranteed by applying 1520v rms for 1s. test voltage is applied between all pins on one side of the package to all pins on the other side of the package, e.g., between pins 1?4 and pins 15?8 on the 28-pin package. note 5: applies to peak current (see typical operating characteristics ). although the MAX1480Ea/MAX1480Ec and max1490ea/max1490eb provide electrical isolation between logic ground and signal paths, they do not provide isolation between external shields and the signal paths (see isolated common connection section). switching characteristics?ax1480ea/max1490ea (continued) (v cc_ = +5v ?0%, v fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = +5v and t a = +25?.) t zh(shdn) 315 figures 6 and 9, c l = 100pf, s2 closed shutdown to driver output high t zh(shdn) 315 ? figures 6 and 9, c l = 100pf, s1 closed parameter symbol min typ max units conditions shutdown to driver output low ? t plh 1.4 3.0 figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf driver input to output propagation delay t phl 1.1 3.0 ? figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf driver disable time from high (MAX1480Ec only) t hz 1.7 4.5 ? figures 6 and 8, c l = 15pf, s2 closed driver disable time from low (MAX1480Ec only) t lz 2.0 4.5 ? figures 6 and 8, c l = 15pf, s1 closed driver enable to output low (MAX1480Ec only) t zl 1.4 4.5 ? figures 6 and 8, c l = 100pf, s1 closed driver enable to output high (MAX1480Ec only) t zh 1.4 4.5 ? figures 6 and 8, c l = 100pf, s2 closed time to shutdown t shdn 100 ? parameter symbol min typ max units driver rise or fall time t r, t f 1.0 2.0 ? |t plh - t phl | differential receiver skew t skd 200 ns receiver input to output propagation delay t phl 1.1 3.0 ? figures 5 and 10, r diff = 54 ? , c l1 = c l2 = 100pf maximum data rate figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf f max 160 kbps shutdown to driver output low t skew , t skd 25% of data period t zl(shdn) t plh 0.9 3.0 315 figures 5 and 10, r diff = 54 ? , c l1 = c l2 = 100pf ? figures 6 and 9, c l = 100pf, s1 closed shutdown to driver output high t zh(shdn) 315 ? figures 6 and 9, c l = 100pf, s2 closed driver output skew conditions t skew 300 1200 ns figures 5 and 7, r diff = 54 ? , c l1 = c l2 = 100pf t skd 30 150 figures 5 and 10, r diff = 54 ? , c l1 = c l2 = 100pf |t plh - t phl | differential receiver skew ns switching characteristics?ax1480ec/max1490eb (v cc_ = +5v ?0%, v fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = +5v and t a = +25?.) t shdn 100 time to shutdown ? f max 2.5 t skew , t skd , t phl 25% of data period maximum data rate mbps
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces _______________________________________________________________________________________ 5 0 output current vs. receiver output low voltage MAX1480E/90e toc01 output low voltage (v) output current (ma) 1.5 10 20 30 40 50 60 70 80 measured at iso ro drv 1.0 0.5 0 3.5 3.0 2.5 2.0 5.0 4.5 4.0 0 output current vs. receiver output high voltage MAX1480E/90e toc02 output high voltage (v) output current (ma) 1.5 -5 measured at iso ro drv 1.0 0.5 0 3.5 3.0 2.5 2.0 5.0 4.5 4.0 -10 -15 -20 -25 -30 3.00 -40 20 receiver output high voltage vs. temperature MAX1480E/90e toc03 temperature ( c) output high voltage (v) 0 -20 60 40 80 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 measured at iso ro drv i ro = 8ma 0 -40 20 receiver output low voltage vs. temperature MAX1480E/90e toc04 temperature ( c) output low voltage (v) 0 -20 60 40 80 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 measured at iso ro drv i ro = 8ma 0 driver output current vs. differential output voltage MAX1480E/90e toc07 differential output voltage (v) output current (ma) 1.5 10 20 30 40 50 60 70 80 di = high or open 1.0 0.5 0 3.5 3.0 2.5 2.0 5.0 4.5 4.0 output current vs. driver output low voltage MAX1480E/90e toc05 output low voltage (v) output current (ma) 0 160 180 140 100 120 80 40 60 0 20 123456789101112 0 -7 output current vs. driver output high voltage MAX1480E/90e toc06 output high voltage (v) output current (ma) 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 2.0 -40 20 driver differential output voltage vs. temperature MAX1480E/90e toc08 temperature ( c) differential output voltage (v) 0 -20 60 40 80 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 di = high or open r l = 54 ? 0 -40 20 shutdown current vs. temperature MAX1480E/90e toc09 temperature ( c) shutdown current ( a) 0 -20 60 40 80 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 sd = v cc_ , di = v cc_ de = v cc_ (MAX1480Ec only) measured at v cc1 and v cc2 __________________________________________typical operating characteristics (v cc_ = +5v, v fs = v cc_ , figures 1 and 2, t a = +25?, unless otherwise noted.)
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 6 _______________________________________________________________________________________ ____________________________typical operating characteristics (continued) (v cc_ = +5v, v fs = v cc_ , figures 1 and 2, t a = +25?, unless otherwise noted.) v cc_ = 5.0v, de = v cc_ di = 0v to 5v at 1 25mhz MAX1480Ea/max1490ea receiver t phl ro 2v/div 20ns/div receiver input a 1v/div receiver input b 1v/div MAX1480E/90e toc14 v cc_ = 5.0v, de = v cc_ MAX1480Ea/max1490ea receiver t plh ro 2v/div 20ns/div receiver input b 1v/div receiver input a 1v/div MAX1480E/90e toc15 0 60 40 20 80 100 120 140 160 MAX1480Ea supply current vs. temperature MAX1480E/90e toc10 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = +5.5v v cc = +5v v cc = +5.5v v cc = +5v v cc = +4.5v r l = 54 ? r l = v cc = +4.5v de = v cc 20 70 60 50 30 40 80 90 100 110 120 MAX1480Ec supply current vs. temperature MAX1480E/90e t0c11 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = +5.5v v cc = +5v v cc = +5.5v v cc = +5v v cc = +4.5v r l = 54 ? r l = v cc = +4.5v de = v cc 80 120 100 140 160 180 200 max1490ea supply current vs. temperature MAX1480E/90e toc12 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = +5.5v v cc = +5v v cc = +5.5v v cc = +5v v cc = +4.5v r l = 54 ? r l = v cc = +4.5v 50 100 90 80 60 70 110 120 130 140 150 max1490eb supply current vs. temperature MAX1480E/90e toc13 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = +5.5v v cc = +5v v cc = +5.5v v cc = +5v v cc = +4.5v r l = 54 ? r l = v cc = +4.5v
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces _______________________________________________________________________________________ 7 v cc = 5 . 0 v , di = 0 v MAX1480Ec driver enable time de 2v/div 500ns/div driver output b 2v/div MAX1480E/90e toc18 _____________________________typical operating characteristics (continued) (v cc_ = +5v, v fs = v cc_ , v di = 0, de toggled 0 to 5v at 5khz, figures 1 and 2, t a = +25?, unless otherwise noted.) v cc = 5.0v, di = 0v MAX1480Ec driver disable time de 2v/div 500ns/div driver output b 2v/div MAX1480E/90e toc19 v di = 0 v sd = 5v to 0 at 1khz MAX1480Ea/max1490ea power-up delay to driver outputs valid driver output b (z for max1490) 2v/div 1 s/div sd 2v/div MAX1480E/90e toc20 v cc =50v de =v cc MAX1480Ec/max1490eb receiver t phl receiver input a 1v/div receiver input b 1v/div ro 2v/div 200ns/div MAX1480E/90e toc16 v cc =50v de =v cc MAX1480Ec/max1490eb receiver t plh receiver input a 1v/div receiver input b 1v/div ro 2v/div 500ns/div MAX1480E/90e toc17
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 8 _______________________________________________________________________________________ ________________________________________________________________pin description max1490ea/ max1490eb MAX1480Ea/ MAX1480Ec iso ro led iso com2 iso com1 20 16 isolated common. for MAX1480Ea/MAX1480Ec, connect to iso com2 (pin 16) (figures 1 and 2). 15 13 isolated receiver output led. internal led anode in MAX1480Ea/MAX1480Ec and led cathode in max1490ea/max1490eb. connect to iso ro drv through a resis- tor (table 1 for MAX1480Ea/MAX1480Ec; table 2 for max1490ea/max1490eb). 16 isolated common. connect to iso com1 (pin 20). iso de drv iso v cc2 iso di drv 17 isolated driver-enable drive. the driver outputs, a and b, are enabled by bringing de high. the driver outputs are high impedance when de is low. if the driver outputs are enabled, the device functions as a line driver. while the driver outputs are high impedance, the device functions as a line receiver. open-collector out- put; must have pullup to iso vcc_ and be connected to iso de in for normal operation (table 1). 18 14 isolated supply voltage. connect to iso v cc1 (pin 26 for MAX1480Ea/ MAX1480Ec, or pin 22 for max1490ea/max1490eb). 19 15 isolated driver-input drive. with de high (MAX1480Ea/MAX1480Ec only), a low on di forces output a low and output b high. similarly, a high on di forces output a high and output b low. connect to iso di in (on the MAX1480Ea/MAX1480Ec only) for normal operation. open-collector output; connect a pullup resistor to iso v cc_ (table 1 for MAX1480Ea/MAX1480Ec, table 2 for max1490ea/max1490eb). di de ro 9 9 driver input. with de high (MAX1480Ea/MAX1480Ec only), a low on di forces output a low and output b high. similarly, a high on di forces output a high and output b low. drives internal led cathode through a resistor (see table 1 for MAX1480Ea/MAX1480Ec, table 2 for max1490ea/max1490eb). 11 driver-enable input. the driver outputs, a and b, are enabled by bringing de high. the driver outputs are high impedance when de is low. if the driver out- puts are enabled, the device functions as a line driver. while the driver outputs are high impedance, the device functions as a line receiver. drives internal led cathode through a resistor (table 1). 11 receiver output. if a > b by 200mv, ro is high; if a < b by 200mv, ro is low. open collector; must have pullup to v cc (table 2). gnd2 v cc5 12 12 logic-side ground. connect to gnd1 (pin 5). 14 logic-side (nonisolated side) +5v supply voltage gnd1 fs sd 5 5 logic-side ground. connect to gnd2 (pin 12). 6 6 frequency select input. if fs = v cc_ or is open, switch frequency is high; if fs = gnd, switch frequency is low. for optimal performance and minimal supply current, connect fs to v cc_ or leave unconnected. 7 7 shutdown input. ground for normal operation. when high, the power oscillator is disabled. name v cc1 ? cc4 d1, d2 pin function 1, 2, 8, 10 1, 2, 8, 10 logic-side (nonisolated side) +5v supply voltages 3, 4 3, 4 internal connections. leave these pins unconnected. ro 13 receiver output. if a > b by 200mv, ro is low; if a < b by 200mv, ro is high. open collector; must have pullup to v cc (table 1).
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces _______________________________________________________________________________________ 9 detailed description the MAX1480Ea/MAX1480Ec/max1490ea/max1490eb are comple te, electrically isolated, rs-485/rs-422 data- communications interface solutions. transceivers, opto- couplers, a power driver, and a transformer in one standard 28-pin dip package (24-pin package for the max1490ea/max1490eb) provide a complete inter- face. signals and power are internally transported across the isolation barrier (figures 1, 2). power is transferred from the logic side (nonisolated side) to the isolated side of the barrier through a center-tapped transformer. signals cross the barrier through high- speed optocouplers. a single +5v supply on the logic side powers both sides of the interface. the MAX1480Ea/MAX1480Ec offer half-duplex communica- tions while the max1490ea/max1490eb feature full- duplex communication. the functional input/output relationships are shown in tables 3 through 6. the MAX1480Ec/max1490eb feature reduced-slew-rate drivers that minimize emi and reduce reflections caused by improperly terminated cables, allowing error-free transmission at data rates up to 160kbps. the MAX1480Ea/max1490ea driver slew rate is not limited, allowing transmission rates up to 2.5mbps. the MAX1480Ec/max1490eb shutdown feature reduces supply current to as low as 0.2? by using the sd pin (see low-power shutdown mode section). drivers are short-circuit current limited and are protect- ed against excessive power dissipation by thermal shutdown circuitry that puts the driver outputs into a high-impedance state. the receiver input has a fail-safe feature that guarantees a logic-high ro (logic-low ro ) output if the input is open circuit. on the MAX1480Ea/MAX1480Ec, the driver outputs are enabled by bringing de high. driver-enable time is typi- cally 1.0?. allow time for the devices to be enabled before sending data (see typical operating characteristics ). when enabled, driver outputs function as line drivers. driver outputs are high impedance when de is low. when outputs are high impedance, they func- tion as line receivers. the MAX1480Ea/MAX1480Ec/max1490ea/max1490eb withstand 1260v rms (1min) or 1520v rms (1s). the logic inputs can be driven from ttl/cmos logic with a series resistor, and the received data output can directly drive ttl or cmos-logic families with only a resistive pullup. low-power shutdown mode the sd pin shuts down the oscillator on the internal power driver. with the primary side in shutdown, no power is transferred across the isolation barrier. the di and de optocouplers, however, still consume current if the drive signals on the nonsolated side are low. therefore, leave di and de high or floating when in shutdown mode. under these conditions, the MAX1480Ec/ max1490eb supply current is reduced to as low as 0.2?. ___________________________________________________pin description (continued) note: for de and di pin descriptions, see detailed block diagram and typical application circuit (figure 1 for MAX1480Ea/ MAX1480Ec, figure 2 for max1490ea/max1490eb). internal connections. leave these pins unconnected. ac2, ac1 23, 24 27, 28 26 22 iso v cc1 isolated supply voltage source inverting driver output and inverting receiver input b 25 isolated receiver-output drive. connect to iso ro led through a resistor (see table 1 for MAX1480Ea/MAX1480Ec, table 2 for max1490ea/max1490eb). iso ro drv 21 24 23 a noninverting driver output and noninverting receiver input isolated driver input. connect to iso di drv for normal operation. iso di in 22 isolated driver-enable input. connect to iso de drv for normal operation. iso de in 21 noninverting receiver input a 20 inverting receiver input b 19 inverting driver output z 18 noninverting driver output y 17 function name max1490ea/ max1490eb MAX1480Ea/ MAX1480Ec pin
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 10 ______________________________________________________________________________________ the high-speed optocouplers on the MAX1480Ea/ MAX1480Ec/max1490ea consume an additional 10ma through v cc5 (v cc4 for the max1490ea). therefore, to completely shut down these devices, use an external p- channel mosfet as shown in figure 3. in normal opera- tion, sd is low, turning the mosfet on and thereby providing power to all the v cc pins. when sd is pulled high, the power oscillator is disabled and the switch is turned off, disconnecting power from the di and de opto- couplers. in normal operating mode, the switch carries only the optocoupler currents, so an on-resistance of sev- eral ohms does not significantly degrade efficiency. ac1 (make no connection) ac2 (make no connection) shield (optional) external rs-485/rs-422 wiring iso v cc1 b d2 d1 v cc2 v cc1 iso ro drv a b a sh iso di in iso de in v cc3 sd fs gnd1 iso com1 iso di drv iso v cc2 iso de drv gnd2 de v cc4 di iso com2 iso ro led v cc5 ro r l r l r4* r5* r7 100 ? r1* r2* r3* r6* de di v in +5v c1 22 f c2 0.1 f logic ground isolation barrier isolated common driver input driver enable receiver output de di ro 74hc86 or equivalent max1487e max487e max845e 1 2 28 27 3 4 5 6 7 8 9 10 11 12 13 14 26 25 24 23 22 21 20 19 18 17 16 15 max845e n MAX1480Ea: max1487e MAX1480Ec: max487e re iso ro drv iso de in iso di in iso com1 iso v cc1 a b r d n q q t f/f v cc3 fs osc 1.07mhz/ 1.45mhz sd gnd1 d2 d1 shield (optional) note: resistor r7 protects the MAX1480Ea from transient currents between shield and transmission lines. twisted pair to other transceivers terminating resistor (one resistor on each end) twisted pair to other transceivers *see table 1. MAX1480Ea MAX1480Ec 270pf 4kv figure 1. MAX1480Ea/MAX1480Ec detailed block diagram and application circuit table 1. pullup and led drive resistors for figure 1 part r1 ( ? ) r2 ( ? ) r3 ( ? ) MAX1480Ea MAX1480Ec 200 200 200 200 1000 3000 r4 ( ? ) 4300 3000 r5 ( ? ) 1000 3000 r6 ( ? ) 200 200
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces ______________________________________________________________________________________ 11 MAX1480Ec/max1490eb: reduced emi and reflections the MAX1480Ec/max1490eb are slew-rate-limited, minimizing emi and reducing reflections caused by improperly terminated cables. figure 11 shows both the driver output waveform of a MAX1480Ea/ max1490ea transmitting a 150khz signal and the fourier analysis of that waveform. high-frequency har- monics with large amplitudes are evident. figure 12 shows the same information for the slew-rate-limited MAX1480Ec/max1490eb transmitting the same signal. the high-frequency harmonics have much lower ampli- tudes, and therefore the potential for emi is significantly reduced. driver output protection there are two mechanisms to prevent excessive output current and power dissipation caused by faults or by bus contention. a foldback current limit on the output stage provides immediate protection against short cir- shield (optional) external rs-485/rs-422 wiring a r l r l b z y r l r l r3* r4* r5, 100 ? sh1 sh2 r1* r2* r6, 100 ? di v in +5v c1 22 f c2 0.1 f logic ground isolation barrier isolated common driver input receiver output di ro 74hc86 or equivalent max845 n max1490ea: max490e max1490eb: max488e iso di drv iso ro drv a b z y d r n q q t f/f v cc3 fs osc 1.07mhz/ 1.45mhz sd gnd1 d2 d1 shield (optional) note: resistors r5 and r6 protect the max1490ea/max1490eb from transient currents between shield and transmission lines. twisted pair to other transceivers terminating resistor (one resistor on each end) twisted pair to other transceivers 24 23 22 21 20 19 18 17 1 2 3 4 5 6 7 8 ac1 (make no connection) ac2 (make no connection) iso v cc1 iso ro drv d2 d1 v cc2 v cc1 a b z y v cc3 sd fs gnd1 16 15 14 13 9 10 11 12 iso com1 iso di drv iso v cc2 iso ro led gnd2 r0 v cc4 di max845 max488e max490e max1490ea/ max1490eb *see table 2. 270 pf 4kv figure 2. max1490ea/max1490eb detailed block diagram and typical application circuit table 2. pullup and led drive resistors for figure 2 max1490eb 200 3000 330 3000 1000 330 1000 200 max1490ea r4 ( ? ) r3 ( ? ) r2 ( ? ) r1 ( ? ) part
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 12 ______________________________________________________________________________________ figure 4. driver dc test load r r v od v oc d isolation barrier figure 5. driver/receiver timing test circuit di c l1 (de ) c l2 ro (ro)* r diff v id isolation barrier ( ) are for the MAX1480Ea/MAX1480Ec. * optocoupler outputs. see figures 1 and 2 for detailed block diagram and typical application circuit. isolation barrier r d test circuits 28 27 26 25 24 23 22 21 1 2 3 4 5 6 7 8 ac1 v in +5v shutdown si9433dy di gnd de r1 r2 r3 p ro ac2 iso v cc1 b d2 d1 v cc2 v cc1 iso ro drv a iso di in iso de in v cc3 sd fs gnd1 20 19 18 17 9 10 11 12 iso com1 iso di drv iso v cc2 iso de drv gnd2 de v cc4 di 16 15 13 14 iso com2 iso ro led v cc5 ro max1487e max845 isolation barrier MAX1480Ea figure 3. MAX1480Ea low-power shutdown mode
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces ______________________________________________________________________________________ 13 figure 6. driver timing test load output under test 500 ? s1 s2 iso v cc _ c l figure 7. driver propagation delays and transition times di 0 b a v o 0 -v o v o t plh 1/2 v o 10% t r 90% 90% t phl 1/2 v o 10% t f v diff = v (a) - v (b) v diff v cc_ - 0.4v v cc_ - 0.4v 2 t skew = ? t plh - t phl ? v cc_ - 0.4v 2 figure 8. driver enable and disable times output normally low output normally high 0 a, b v ol a, b 0 v ol + 0.5v v cc_ - 0.4v 2 v cc_ - 0.4v 2 v cc_ -0.4v v oh - 0.5v 2.3v 2.3v t zl t lz t zh t hz de figure 9. times to/from shutdown output normally low output normally high 2.4v 0.8v a, b v ol a, b 0 1.6v 1.6v v ol + 0.5v v oh - 0.5v 2.3v 2.3v t zl(shdn) t shdn t zh(shdn) t shdn sd figure 10. receiver propagation delays v oh v ol -v id v id 1.5v 0 1.5v 1.5v 1.5v MAX1480Ea/MAX1480Ec output max1490ea/max1490eb output input 0 ro ro v oh v ol v a - v b t phl t plh t plh t phl t skew = ? t plh - t phl ? switching waveforms ____________________________________________________test circuits (continued)
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 14 ______________________________________________________________________________________ cuits over the entire common-mode range (see typical operating characteristics ). in addition, a thermal shut- down circuit forces the driver outputs into a high-im pedance state if the die temperature rises excessively. propagation delay skew propagation delay skew is the difference between the low-to-high and high-to-low propagation delay. small driver/receiver skew times help reduce emi and reflec- tions by maintaining balanced differential signals. table 3. transmitting table 4. receiving table 5. transmitting table 6. receiving 1 x inputs* 1 high-z outputs 0 high-z 1 0 figure 11. driver output waveform and fft plot of MAX1480Ea/max1490ea transmitting a 150khz signal 10db/div 0 5mhz 500khz/div figure 12. driver output waveform and fft plot of MAX1480Ec/ max1490eb tra nsmitting a 150khz signal 10db/div 0 5mhz 500khz/div _____________________function tables half-duplex devices (MAX1480Ea/MAX1480Ec) full-duplex devices (max1490ea/max1490eb) di a b de 0 0 1 1 +0.2v open inputs* 0 0 v a - v b output (ro) de -0.2v 1 0 0 0 0 1 z y 1 0 0 1 1 1 output (ro) 0 -0.2v +0.2v open input (v a - v b ) x = don? care; high-z = high impedance * for de and di pin descriptions, see detailed block diagram and typical application circuit (figure 1 for MAX1480Ea/ MAX1480Ec, figure 2 for max1490ea/max1490eb). outputs input * (di )
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces ______________________________________________________________________________________ 15 ___________applications information these e versions of the MAX1480Ea/MAX1480Ec/ 1490ea/max1490eb provide extra protection against esd. the rugged MAX1480Ea/MAX1480Ec/max1490ea/ max1490eb are intended for harsh environments where high-speed communication is important. these devices eliminate the need for transient suppressor diodes or the use of discrete protection components. the standard (non-e) max1480a/max1480c/max1490a/max1490b are recommended for applications where cost is critical. 15kv esd protection as with all maxim devices, esd-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. the driver outputs and receiver inputs have extra protec- tion against static electricity. maxim? engineers devel- oped state-of-the-art structures to protect these pins against esd of ?5kv without damage. the esd struc- tures withstand high esd in all states: normal operation, shutdown, and powered down. after an esd event, maxim? MAX1480Ea/MAX1480Ec/max1490ea/ max1490eb keep working without latchup. an isolation capacitor of 270pf 4kv should be placed between iso com and logic ground for optional performance against an esd pulse with respect to logic ground. esd protection can be tested in various ways; the trans- mitter outputs and receiver inputs of this product family are characterized for protection to ?5kv using the human body model. esd test conditions the ?5kv esd test specifications apply only to the a, b, y, and z i/o pins. the test surge may be referenced to either the iso com or to the nonisolated gnd (figures 1 and 2). human body model figure 13 shows the human body model, and figure 14 shows the current waveform it generates when dis- charged into low impedance. this model consists of a 100pf capacitor charged to the esd voltage of interest, which is then discharged into the test device through a 1.5k ? resistor. machine model the machine model for esd tests all pins using a 200pf storage capacitor and zero discharge resistance. its objective is to simulate the stress caused by contact that occurs with handling and assembly during manufactur- ing. all pins require this protection during manufactur- ing?ot just inputs and outputs. therefore, after pc board assembly, the machine model is less relevant to i/o ports. the MAX1480Ea/MAX1480Ec are designed for bidirec- tional data communications on multipoint bus-transmis- sion lines. the max1490ea/max1490eb are designed for full-duplex bidirectional communications that are pri- marily point-to-point. figures 15 and 16 show half-duplex and full-duplex typical network application circuits, respectively. to minimize reflections, terminate the line at both ends with its characteristic impedance, and keep stub lengths off the main line as short as possible. the slew-rate-limited MAX1480Ec/max1490eb are more tol- erant of imperfect termination and stubs off the main line. layout considerations the MAX1480Ea/MAX1480Ec/max1490ea/max1490eb pinouts enable optimal pc board layout by minimizing interconnect lengths and crossovers: ? for maximum isolation, the ?solation barrier?should not be breached except by the MAX1480Ea/ charge-current limit resistor discharge resistance storage capacitor c s 100pf r c r d 1500 ? high- voltage dc source device under test 1m ? 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 13. human body esd test model figure 14. human body current waveform
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 16 ______________________________________________________________________________________ di 100 ? de ro b a r d re ro de di r 120 ? d a b re re di de ro b a r d ac1 (make no connection) ac2 (make no connection) shield (optional) note: resistor r7 protects the MAX1480Ea/MAX1480Ec from transient currents between shield and transmission lines. iso v cc1 b d2 d1 v cc2 v cc1 iso ro drv a b a sh iso di in iso de in v cc3 sd fs gnd1 iso com1 iso di drv iso v cc2 iso de drv gnd2 de v cc4 di iso com2 iso ro led v cc5 ro r4 r5 r7 100 ? 120 ? r1 r2 r3 r6 v in +5v c1 22 f c2 0.1 f MAX1480Ea/ MAX1480Ec logic ground isolation barrier isolated common terminating resistor (one resistor on each end) driver input driver enable receiver output de di ro 74hc86 or equivalent max487e max1487e max845e 1 2 28 27 3 4 5 6 7 8 9 10 11 12 13 14 26 25 24 23 22 21 20 19 18 17 16 15 terminating resistor (one resistor on each end) 270pf 4kv figure 15. typical half-duplex rs-485/rs-422 network
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces ______________________________________________________________________________________ 17 MAX1480Ec/max1490ea/max1490eb. connections and components from one side should not be locat- ed near those of the other side. ? a shield trace connected to the ground on each side of the barrier can help intercept capacitive currents that might otherwise couple into the signal path. in a double-sided or multilayer board, these shield traces should be present on all conductor layers. ? try to maximize the width of the isolation barrier wherever possible; a clear space of at least 0.25 inches between ground and isolated common is suggested. pullup and led drive resistors the MAX1480Ea/MAX1480Ec/max1490ea/max1490eb are specified and characterized using the resistor val- ues shown in tables 1 and 2. altering the recommend- ed values can degrade performance. di and de are intended to be driven through a series current-limiting resistor. directly grounding these pins destroys the device. the di and de (MAX1480Ea/MAX1480Ec only) inputs are the cathodes of leds whose anodes are connected to the supply. these points are best driven by a cmos- logic gate with a series resistor to limit the current. the resistor values shown in tables 1 and 2 are recommend- ed when the 74hc86 gate or equivalent is used. these values may need to be adjusted if a driving gate with dis- similar series resistance is used. all pullup resistors are based on optocoupler specifica- tions in order to optimize the devices?data-transfer rates. isolated common connection the isolated common may be completely floating with respect to the logic ground and the effective network ground. the receiver input resistors cause the isolated common voltage to go to the mean voltage of the receiver inputs. if using shielded cable, connect the isolated com- mon to the shield through a 100 ? resistor. in the case of the max1490ea/max1490eb, each shield s hould have its own 100 ? resistor (figures 1, 2, 15, and 16). double-isolated rs-485 repeater the rs-422/rs-485 standard is specified for cable lengths up to 4000 feet. when approaching or exceeding the specified maximum cable length, a ground-potential difference of several tens of volts can easily develop. this difference can be either dc, ac, at power-line fre- quency, or any imaginable noise or impulse waveform. it is typically very low impedance so that if a connection between the two grounds is attempted, very large cur- shield (optional) note: resistors r5 and r6 protect the max1490ea/max1490eb from transient currents between shield and transmission lines. 120 ? 120 ? 120 ? a b z y y z r3 r4 r5, 100 ? sh1 sh2 r1 r2 r6, 100 ? di v in +5v c1 22 f c2 0.1 f logic ground isolation barrier isolated common driver input receiver output di ro 74hc86 or equivalent shield (optional) 24 23 22 21 20 19 18 17 1 2 3 4 5 6 7 8 ac1 (make no connection) ac2 (make no connection) iso v cc1 iso ro drv d2 d1 v cc2 v cc1 a b z y v cc3 sd fs gnd1 16 15 14 13 9 10 11 12 iso com1 iso di drv iso v cc2 iso ro led gnd2 ro v cc4 di max845e max488e max490e d di ro 120 ? b a r max1490ea/ max1490eb 270pf 4kv figure 16. typical full-duplex rs-485/rs-422 network
MAX1480E/max1490e 15kv esd-protected, isolated rs-485/rs-422 data interfaces 18 ______________________________________________________________________________________ rents may flow. these currents are by their nature unsta- ble and unpredictable. in addition, they may cause noise to be injected into sensitive instrumentation and, in severe cases, might actually cause physical damage to such equipment. figure 17 shows a half-duplex (2-wire), bidirectional, party-line repeater system that prevents interference and/or damage from ground-potential differences. two MAX1480Ea/MAX1480Ec isolated rs-485 transceivers are used to isolate each of the network segments from the electrical environment of the repeater. the MAX1480Ea/MAX1480Ec also regenerate bus signals that may have been degraded by line attenuation or dis- persion. in the idle state, both transmitters are disabled, while all receivers in the system are enabled. if any device on the system has information for any other device, it starts sending its data onto the bus. each data transmission on the bus retriggers the one-shot, keeping the sending transmitter enabled until there are no more transmis- sions. all receivers receive all data; if this is undesirable, the protocol must allow for an address field so receivers can ignore data not directed to them. each node must refrain from transmitting when data already exists on the bus, and must resend data that is corrupted by the collisions that inevitably occur with a party-line system. with the repeater of figure 17, there might be transmitters up to 8000 feet apart. that repre- sents more than 8? (assuming 1ns/foot of delay) in which two nodes could be transmitting simultaneously. the circuit in figure 17 can be used either directly as shown, with the slew-rate-limited MAX1480Ec, for data transfer rates up to 160kbps, or with the MAX1480Ea for data rates up to 2.5mbps (see table 1 for pullup and led resistor values when using the MAX1480Ea). if dual- port isolation is not needed, one of the MAX1480Ec devices can be replaced by a max487e for 250kbps applications. reliability these products contain transformers, optocouplers, and capacitors, in addition to several monolithic ics and diodes. as such, the reliability expectations more closely represent those of discrete optocouplers rather than the more robust characteristics of monolithic silicon ics. the reliability testing programs for these multicomponent devices may be viewed on the maxim website (www.maxim-ic.com) under technical support, technical reference, multichip products. 2 8 3k ? 3k ? 3k ? 5712 5712 11 23 13 1 3k ? 2 43 13 3k ? 74hc04 200 ? 9 25 25 23 26 a b a b 19 9 200 ? 200 ? driver enable b > a 200 ? 74hc123 clr 4 aq 311 1 driver enable a > b 11 22 17 200 ? 15 21 24 24 10 14 network segment a network segment b 2 8 10 14 clr 74hc123 12 aq 9 3k ? 26 19 22 17 200 ? 15 21 1000pf 51k ? +5v +5v +5v +5v 51k ? 16 15 14 13 2b q 1000pf 7 6 5 10 bq MAX1480Ec MAX1480Ec figure 17. double-isolated rs-485 repeater
15kv esd-protected, isolated rs-485/rs-422 data interfaces MAX1480E/max1490e maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 (408) 737-7600___________________ 19 2001 maxim integrated products printed usa is a registered trademark of maxim integrated products. ordering information (continued) pin configurations (continued) 28 27 26 25 24 23 22 21 1 2 3 4 5 6 7 8 ac1 ac2 iso v cc1 b d2 d1 v cc2 v cc1 iso ro drv a iso di in iso de in v cc3 sd fs gnd1 20 19 18 17 9 10 11 12 iso com1 iso di drv iso v cc2 iso de drv gnd2 de v cc4 di 16 15 13 14 iso com2 iso ro led v cc5 ro max487e max1487e max845 isolation barrier dip top view MAX1480Ea/ MAX1480Ec ? data rate for a parts is up to 2500kbps. data rate for c parts is up to 250kbps. selector guide part ? temp. range pin-package 28 wide plastic dip 0? to +70? MAX1480Ec cpi MAX1480Ecepi -40? to +85? 28 wide plastic dip 24 wide plastic dip 0? to +70? max1490ea cpg max1490eaepg -40? to +85? 24 wide plastic dip 24 wide plastic dip 0? to +70? max1490eb cpg max1490ebepg -40? to +85? 24 wide plastic dip max1490eb full 0.25 yes no 2.5 full max1490ea MAX1480Ec half 0.25 yes no 2.5 half MAX1480Ea slew- rate limited data rate (mbps) half/ full duplex part this device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board-level solder attach and rework. maxim recommends the use of the solder profiles rec- ommended in the industry-standard specification, jedec 020a, paragraph 7.6, table 3 for ir/vpr and convection reflow processes. preheating, per this standard, is required. hand or wave soldering is not recommended.

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