View MAX1480BCPI_9078069.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

_________________ general description the max1480a/max1480b/max1480c/max1490a/ max1490b are complete, electrically isolated, rs-485/ rs-422 data-communications interface solutions in a hybrid microcircuit. transceivers, optocouplers, and a transformer provide a complete interface in a standard dip package. a single +5v supply on the logic side pow- ers both sides of the interface. the max1480b/max1480c/max1490b feature reduced- slew-rate drivers that minimize emi and reduce reflec- tions caused by improperly terminated cables, allowing error-free data transmission at data rates up to 250kbps. the max1480a/max1490a driver slew rate is not limited, allowing transmission rates up to 2.5mbps. the max1480a/b/c are designed for half-duplex communi- cation, while the max1490a/b feature full-duplex com- munication. 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 max1480a/b/c, ro high for the max1490a/b) if the input is open circuit. the max1480a/max1480b/max1480c/max1490a/ max1490b typically withstand 1600v rms (1 minute) or 2000v rms (1 second). their isolated outputs meet all rs-485/rs-422 specifications. the max1480a/b/c are available in a 28-pin dip package, and the max1490a/b 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 next-generation device features ? ? for integrated esd protection max1480e/max1490e: 15kv esd-protected, isolated rs-485/rs-422 data interfaces ? ? for space-constrained applications max3157: high cmrr, rs-485 transceiver with 50v isolation max1480a/b/c/max1490a/b complete, isolated rs-485/rs-422 data interface ________________________________________________________________ maxim integrated products 1 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 max1490a/b max845 max488 max490 top view isolation barrier pin configurations 19-0259; rev 5; 5/05 _______________ordering information ordering information continued at end of data sheet. ? data rate for ??parts is up to 2.5mbps. data rate for ??and ??parts is up to 250kbps. pin configurations continued at end of data sheet. for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part ? temp range pin-package max1480a cpi 0? to +70? 28 wide plastic dip max1480aepi -40? to +85? 28 wide plastic dip _____________________selection table part half/ full duplex data rate (mbps) slew- rate limited driver enable time (s) max1480a half 2.5 no 0.2 max1480b half 0.25 yes 35 max1480c half 0.25 yes 0.5 max1490a full 2.5 no max1490b full 0.25 yes
complete, isolated rs-485/rs-422 data interface 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 max1480_cpi/max1490_cpg ............................0? to +70? max1480_epi/max1490_epg .........................-40? to +85? storage temperature range .............................-65? to +160? lead temperature (soldering, 10s) .................................+300? max1480a/b/c/max1490a/b parameter symbol conditions min typ max units f swl v fs = 0v 535 switch frequency f swh fs = v cc_ or open 725 khz r l = , +25 c only 60 90 max1480a, de = v cc_ or open r l = 54 120 r l = , +25 c only 35 45 max1480b, de = v cc_ or open r l = 54 95 r l = , +25 c only 35 75 max1480c, de = v cc_ or open r l = 54 95 r l = , +25 c only 100 150 max1490a r l = 54 170 r l = , +25 c only 65 125 operating supply current i cc max1490b r l = 54 130 ma shutdown supply current (note 3) i shdn sd = v cc_ 0.2 ? v sdh high 2.4 shutdown input threshold v sdl low 0.8 v shutdown input leakage current 10 pa v fsh high 2.4 fs input threshold v fsl low 0.8 v fs input pullup current fs low 50 ? fs input leakage current fs high 10 pa input high voltage v ih de , di v cc_ - 0.4 v input low voltage v il de , di 0.4 v isolation resistance r iso t a = +25 c, v iso = 50vdc 100 10,000 m isolation capacitance c iso t a = +25 c, v iso = 50vdc 10 pf differential driver output (no load) v od1 8v
max1480a/b/c/max1490a/b complete, isolated rs-485/rs-422 data interface _______________________________________________________________________________________ 3 parameter symbol conditions min typ max units r = 50 (rs-422) 2 differential driver output (with load) v od2 r = 27 (rs-485), figure 4 1.5 5.0 v differential 0.3 change in magnitude of differential output voltage for complementary output states v od r = 27 or 50 , figure 4 common mode 0.3 v driver common-mode output voltage v oc r = 27 or 50 , figure 4 4 v max1480a/b/c 1 v in = 12v max1490a/b 0.25 max1480a/b/c 0.8 input current (a, b) iso i in de = 0v, v cc_ = 0v or 5.5v v in = -7v max1490a/b 0.2 ma max1480a/b/c 48 receiver input resistance r in -7v v cm 12v max1490a/b 12 k receiver differential threshold voltage v th -7v v cm 12v -0.2 +0.2 v receiver input hysteresis v th v cm = 0v 70 mv receiver output /receiver output low voltage v ol using resistor values listed in tables 1 and 2 0.4 v receiver output /receiver output high current i oh v out = 5.5v 250 ? driver short-circuit current iso i osd -7v v o 12v (note 4) 100 ma 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 characteristicsmax1480a/max1490a (v cc_ = 5v ?0%, fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = 5v and t a = +25?.) parameter symbol conditions min typ max units t plh 100 275 driver input to output propagation delay t phl figures 5 and 7, r diff = 54 , c l1 = c l2 = 100pf 100 275 ns driver output skew t skew figures 5 and 7, r diff = 54 , c l1 = c l2 = 100pf 25 90 ns driver rise or fall time t r, t f figures 5 and 7, r diff = 54 , c l1 = c l2 = 100pf 15 40 ns driver enable to output high (max1480a only) t zh figures 6 and 8, c l = 100pf, s2 closed 0.2 1.5 ? driver enable to output low (max1480a only) t zl figures 6 and 8, c l = 100pf, s1 closed 0.2 1.5 ? driver disable time from low (max1480a only) t lz figures 6 and 8, c l = 15pf, s1 closed 0.2 1.5 ? driver disable time from high (max1480a only) t hz figures 6 and 8, c l = 15pf, s2 closed 0.2 1.5 ? t plh 100 225 receiver input to output propagation delay t phl figures 5 and 10, r diff = 54 , c l1 = c l2 = 100pf 100 225 ns
max1480a/b/c/max1490a/b complete, isolated rs-485/rs-422 data interface 4 _______________________________________________________________________________________ switching characteristicsmax1480a/max1490a (continued) (v cc_ = 5v ?0%, fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = 5v and t a = +25?.) parameter symbol conditions min typ max units |t plh - t phl | differential receiver skew t skd figures 5 and 10, r diff = 54 , c l1 = c l2 = 100pf 20 ns maximum data rate f max t plh , t phl < 50% of data period 2.5 mbps time to shutdown t shdn 100 ? shutdown to driver output high t zh ( shdn ) figures 6 and 9, c l = 100pf, s2 closed 3 10 s shutdown to driver output low t zl ( shdn ) figures 6 and 9, c l = 100pf, s1 closed 3 10 s switching characteristicsmax1480b/max1480c/max1490b (v cc_ = 5v ?0%, fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = 5v and t a = +25?.) parameter symbol conditions min typ max units t plh 2 3.0 driver input to output propagation delay t phl figures 5 and 7, r diff = 54 , c l1 = c l2 = 100pf 2 3.0 ? driver output skew t skew figures 5 and 7, r diff = 54 , c l1 = c l2 = 100pf 900 1600 ns driver rise or fall time t r, t f figures 5 and 7, r diff = 54 , c l1 = c l2 = 100pf 1.0 2.0 ? driver enable to output high (max1480b only) t zh figures 6 and 8, c l = 100pf, s2 closed 35 100 ? driver enable to output low (max1480b only) t zl figures 6 and 8, c l = 100pf, s1 closed 35 100 ? driver disable time from low (max1480b only) t lz figures 6 and 8, c l = 15pf, s1 closed 13 50 ? driver disable time from high (max1480b only) t hz figures 6 and 8, c l = 15pf, s2 closed 13 50 ? driver enable to output high (max1480c only) t zh figures 6 and 8, c l = 100pf, s2 closed 0.5 4.5 ? driver enable to output low (max1480c only) t zl figures 6 and 8, c l = 100pf, s1 closed 0.5 4.5 ?
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface _______________________________________________________________________________________ 5 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 max1480a/ max1480b/max1480c, figure 2 for max1490a/max1490b). note 3: shutdown supply current is the current at v cc1 and v cc2 when shutdown is enabled. note 4: applies to peak current (see typical operating characteristics ). although the max1480a/b/c and max1490a/b 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 characteristicsmax1480b/max1480c/max1490b (continued) (v cc_ = 5v ?0%, fs = v cc_ , t a = t min to t max , unless otherwise noted. typical values are at v cc_ = 5v and t a = +25?.) parameter symbol conditions min typ max units driver disable time from low (max1480c only) t lz figures 6 and 8, c l = 15pf, s1 closed 2.0 4.5 ? driver disable time from high (max1480c only) t hz figures 6 and 8, c l = 15pf, s2 closed 2.0 4.5 ? t plh 2 3.0 receiver input to output propagation delay t phl figures 5 and 10, r diff = 54 , c l1 = c l2 = 100pf 2 3.0 ? |t plh - t phl | differential receiver skew t skd figures 5 and 10, r diff = 54 , c l1 = c l2 = 100pf 1200 ns maximum data rate f max t plh , t phl < 50% of data period 0.25 mbps time to shutdown t shdn 100 ? shutdown to driver output high t zh ( shdn ) figures 6 and 9, c l = 100pf, s2 closed 35 100 ? shutdown to driver output low t zl ( shdn ) figures 6 and 9, c l = 100pf, s1 closed 35 100 ?
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 6 _______________________________________________________________________________________ 0 output current vs. receiver output low voltage max1480/90a/b-01 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 max1480/90a/b-02 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 max1480/90a/b-03 temperature (?) 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 max1480/90a/b-04 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 max1480/90a/b-07 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 max1480/90a/b-05 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 max1480/90a/b-06 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 max1480/90a/b-08 temperature (?) 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 max1480b/max1480c/max1490b shutdown current vs. temperature max1480/90a/b-09 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 (max1480b/c only) = v cc_ measured at v cc1 and v cc2 __________________________________________typical operating characteristics (v cc_ = 5v, fs = v cc_ , t a = +25?, unless otherwise noted.)
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface _______________________________________________________________________________________ 7 _____________________________typical operating characteristics (continued) (v cc_ = 5v, fs = v cc_ , t a = +25?, unless otherwise noted.) 0 60 40 20 80 100 120 140 160 max1480a supply current vs. temperature max1480/90a/b-10 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = 5.5v v cc = 5.0v v cc = 5.5v v cc = 5.0v v cc = 4.5v r l = 54 r l = v cc = 4.5v de = v cc 20 60 40 80 100 120 140 max1480b supply current vs. temperature max1480/90a/b-11 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = 5.5v v cc = 5.0v v cc = 5.5v v cc = 5.0v r l = 54 r l = de = v cc v cc = 4.5v v cc = 4.5v 20 70 60 50 30 40 80 90 100 110 120 max1480c supply current vs. temperature max1480/90a/b-12 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = 5.5v v cc = 5.0v v cc = 5.5v v cc = 5.0v v cc = 4.5v r l = 54 r l = v cc = 4.5v de = v cc 80 120 100 140 160 180 200 max1490a supply current vs. temperature max1480/90a/b-13 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = 5.5v v cc = 5.0v v cc = 5.5v v cc = 5.0v v cc = 4.5v r l = 54 r l = v cc = 4.5v 50 100 90 80 60 70 110 120 130 140 150 max1490b supply current vs. temperature max1480/90a/b-14 temperature ( c) supply current (ma) -40 -20 0 20 40 60 80 v cc = 5.5v v cc = 5.0v v cc = 5.5v v cc = 5.0v v cc = 4.5v r l = 54 r l = v cc = 4.5v 0.1 10 1 100 driver disable time vs. temperature max1480/90a/b-15a temperature ( c) driver disable time ( s) -40 -20 0 20 40 60 80 max1480a max1480b max1480c r l = 54 v di = 0v measured from de to valid output 0.1 10 1 100 driver enable time vs. temperature max1480/90a/b-15b temperature ( c) driver enable time ( s) -40 -20 0 20 40 60 80 max1480a max1480c max1480b r l = 54 v di = 0v measured from de to valid output
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 8 _______________________________________________________________________________________ v cc_ = 5.0v, di = 0v de toggled 0v to 5v at 5khz max1480b driver enable time driver output b 2v/div de 2v/div 10 s/div max1480/90-17 v cc_ = 5.0v, di = 0v de toggled 0v to 5v at 5khz max1480b driver disable time de 2v/div 5 s/div driver output b 2v/div max1480/90-18 v cc_ = 5.0v, di = 0v de toggled 0v to 5v at 5kh max1480c driver enable time de 2v/div 500ns/div driver output b 2v/div max1480/90-25 v cc_ = 5.0v, di = 0v de toggled 0v to 5v at 5khz max1480c driver disable time de 2v/div 500ns/div driver output b 2v/div max1480/90-26 v cc_ = 5.0v, di = 0v de toggled 0v to 5v at 5khz max1480a driver enable time de 2v/div 200ns/div driver output b 2v/div max1480/90-19 _____________________________typical operating characteristics (continued) (v cc_ = 5v, fs = v cc_ , v di = 0v, de toggled 0v to 5v at 5khz, t a = +25?, unless otherwise noted.) v cc_ = 5.0v, di = 0v de toggled 0v to 5v at 5khz max1480a driver disable time de 2v/div 200ns/div driver output b 2v/div max1480/90-20
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface _______________________________________________________________________________________ 9 _____________________________typical operating characteristics (continued) (v cc_ = 5v, fs = v cc_ , de = v cc_ , v di = 0v to 5v at 1.25mhz, t a = +25?, unless otherwise noted.) v cc_ = 5.0v, de = v cc_ di = 0v to 5v at 1.25mhz max1480a/max1490a receiver t phl ro/ro 2v/div 20ns/div receiver input a 1v/div receiver input b 1v/div max1480/90-21 v cc_ = 5.0v, de = v cc_ di = 0v to 5v at 1.25mhz max1480a/max1490a receiver t plh ro/ro 2v/div 20ns/div receiver input b 1v/div receiver input a 1v/div max1480/90-22 v cc_ = 5.0v, de = v cc_ di = 0v to 5v at 125khz max1480b/max1480c/max1490b receiver t phl receiver input a 1v/div receiver input b 1v/div ro/ro 2v/div 200ns/div max1480/90-23 v cc_ = 5.0v, de = v cc_ di = 0v to 5v at 125khz max1480b/max1480c/max1490b receiver t plh receiver input a 1v/div receiver input b 1v/div ro/ro 2v/div 500ns/div max1480/90-24 v di = 0v v sd = 5v to 0v at 1khz power-up delay to driver outputs valid driver output b (z for max1490) 2v/div 1 s/div sd 2v/div max1480/90-16
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 10 ______________________________________________________________________________________ ________________________________________________________________ pin description internal connections. leave these pins unconnected. 3, 4 3, 4 logic-side (nonisolated side) +5v supply voltages 1, 2, 8, 10 1, 2, 8, 10 function pin d1, d2 v cc1 ? cc4 name shutdown input. ground for normal operation. when high, the power oscillator is disabled. 7 7 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. 6 6 logic-side ground. connect to gnd2 (pin 12). 5 5 sd fs gnd1 logic-side (non-isolated side) +5v supply voltage 14 receiver output . if a > b by 200mv, ro will be low; if a < b by 200mv, ro will be high. open collector; must have pullup to v cc_ (table 1 of figure 1). 13 logic-side ground. connect to gnd1 (pin 5). 12 12 v cc5 ro gnd2 receiver output. if a > b by 200mv, ro will be high; if a < b by 200mv, ro will be low. open collector; must have pullup to v cc (table 2 of figure 2). 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 of figure 1). 11 driver input. with de high (max1480a/b/c 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 (table 1 of figure 1 for max1480a/b/c, table 2 of figure 2 for max1490a/b). 9 9 ro de di isolated driver-input drive. with de high (max1480a/b/c 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 max1480a/b/c only) for normal operation. open-collector output; connect a pullup resistor to iso v cc_ (table 1 of figure 1 for max1480a/b/c; table 2 of figure 2 for max1490a/b). 15 19 isolated supply voltage. connect to iso v cc1 (pin 26 for max1480a/b/c, or pin 22 for max1490a/b). 14 18 isolated driver-enable drive. the driver outputs, a and b, are enabled by bring- ing de high. the driver outputs are high impedance when de is low. if the driv- er 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 output; must have pullup to iso v cc_ and be connected to iso de in for normal operation (table 1 of figure 1). 17 iso di drv iso v cc2 iso de drv isolated common. connect to iso com1 (pin 20). 16 isolated receiver output led. internal led anode in max1480a/b/c and led cathode in max1490a/b. connect to iso ro drv through a resistor (table 1 of figure 1 for max1480a/b/c; table 2 of figure 2 for max1490a/b). 13 15 isolated common. for max1480a/b/c, connect to iso com2 (pin 16) (figures 1 and 2). 16 20 iso com1 iso com2 iso ro led max1480a/b/c max1490a/b pins on the non-isolated side pins on the isolated rs-485/rs-422 side pins on the non-isolated side pins on the isolated rs-485/rs-422 side
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface ______________________________________________________________________________________ 11 detailed description the max1480a/max1480b/max1480c/max1490a/ max1490b are complete, electrically isolated, rs-485/ rs-422 data-communications interface solutions. transceivers, optocouplers, a power driver, and a transformer in one standard 28-pin dip package (24- pin for the max1490a/b) provide a complete interface. 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 optocou- plers. a single +5v supply on the logic side powers both sides of the interface. the max1480a/b/c offer half-duplex communications while the max1490a/b feature full-duplex communication. the functional input/output relationships are shown in tables 3?. the max1480b/max1480c/max1490b feature reduced- slew-rate drivers that minimize emi and reduce reflec- tions caused by improperly terminated cables, allowing error-free transmission at data rates up to 250kbps. the max1480a/max1490a driver slew rate is not limited, allowing transmission rates up to 2.5mbps. the max1480b/max1480c/max1490b shutdown feature reduces supply current to as low as 0.2? by using the sd pin (see the low-power shutdown mode section). use the fs pin to select between high and low switching frequencies for the isolated power driver. the driver switches at the lower frequency 535khz when fs is low, and at the higher frequency 725khz when fs is high. the fs pin has a weak internal pull-up that switches the device to the high-frequency mode when fs is left unconnected. with fs high or open, no-load supply current is reduced by approximately 4ma, and by up to 8ma when fully loaded. for optimal performance and minimal supply current, connect fs to v cc_ or leave unconnected. 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 max1480a/b/c, the driver outputs are enabled by bringing de high. driver-enable times are typically 0.2? for the max1480a, 35? for the max1480b, and 0.5? for the max1480c. allow time for the devices to be enabled before sending data (see the driver enable time vs. temperature graph in the typical operating characteristics ). when enabled, driver outputs function as line drivers. driver outputs are high impedance when de is low. while outputs are high impedance, they func- tion as line receivers. ___________________________________________________ pin description (continued) note: for de and di pin descriptions, see detailed block diagram and typical application circuit (figure 1 for max1480a/b/c, figure 2 for max1490a/b). pin max1490a/b max1480a/b/c a iso ro drv b 23 noninverting driver output and noninverting receiver input 24 21 isolated receiver-output drive. connect to iso ro led through a resistor (table 1 of figure 1 for max1480a/b/c, table 2 of figure 2 for max1490a/b). 25 inverting driver output and inverting receiver input iso v cc1 ac2, ac1 26 22 isolated supply voltage source 27, 28 23, 24 internal connections. leave these pins unconnected. iso di in 22 isolated driver input. connect to iso di drv for normal operation. z 18 inverting driver output b a iso de in 19 inverting receiver input 20 noninverting receiver input 21 isolated driver-enable input. connect to iso de drv for normal operation. name function y 17 noninverting driver output pins on the isolated rs-485/rs-422 side (continued)
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 12 ______________________________________________________________________________________ the max1480a/max1480b/max1480c/max1490a/ max1490b typically withstand 1600v rms (1 minute) or 2000v rms (1 second). 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 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 nonisolated side are low. therefore, leave di and de high or floating when in shutdown mode. 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 22 f 0.1 f c1 c2 max1480a/b/c logic ground isolation barrier isolated common driver input driver enable receiver output de di ro 74hc86 or equivalent max1487 max487 max845 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 max845 n max1480a: max1487 max1480b: max487 max1480c: max487 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 max1480a/b/c 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 figure 1. max1480a/max1480b/max1480c detailed block diagram and typical application circuit 200 510 r2 () 4300 2200 r4 () 1000 3000 r3 () 200 200 r6 () 1000 3000 r5 () 200 max1480a 200 max1480b r1 () part table 1. pull-up and led drive resistors 200 3000 3000 200 3000 200 max1480c
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface ______________________________________________________________________________________ 13 under these conditions, the max1480b/max1480c/ max1490b supply current is reduced to as low as 0.2?. the high-speed optocouplers on the max1480a/ max1480c/max1490a consume an additional 10ma through v cc5 (v cc4 for the max1490a). 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 pro- viding 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 optocou- plers. in normal operating mode, the switch carries only the optocoupler currents, so an on-resistance of several ohms will not significantly degrade efficiency. 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 22 f 0.1 f c1 c2 max1490a/b logic ground isolation barrier isolated common driver input receiver output di ro 74hc86 or equivalent max845 n max1490a: max490 max1490b: max488 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 max1490a/b 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 max488 max490 figure 2. max1490a/max1490b detailed block diagram and typical application circuit table 2. pull-up and led drive resistors 1000 3000 r2 () 1000 3000 r4 () 330 330 r3 () 200 max1490a 200 max1490b r1 () part
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 14 ______________________________________________________________________________________ figure 4. driver dc test load r r v od v oc d figure 5. driver/receiver timing test circuit di c l1 (de ) c l2 ro (ro)* r diff v id isolation barrier ( ) are for the max1480a/b/c * 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 si943304 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 max1487 max845 isolation barrier max1480a figure 3. max1480a low-power shutdown mode
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface ______________________________________________________________________________________ 15 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 0v b a v o 0v -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 0v a, b v ol a, b 0v 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 0v 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 0v 1.5v 1.5v 1.5v max1480a/b/c output max1490a/b output input 0v 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)
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 16 ______________________________________________________________________________________ max1480b/max1480c/max1490b: reduced emi and reflections the max1480b/max1480c/max1490b are slew-rate- limited, minimizing emi and reducing reflections caused by improperly terminated cables. figure 11 shows both the driver output waveform of a max1480a/max1490a transmitting a 150khz signal and the fourier analysis of that waveform. high-fre- quency harmonics with large amplitudes are evident. figure 12 shows the same information for the slew-rate- limited max1480b/max1480c/max1490b transmitting the same signal. the high-frequency harmonics have much lower amplitudes, and therefore the potential for emi is significantly reduced. 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 max1480a/max1490a transmitting a 150khz signal 10db/div 0hz 5mhz 500khz/div figure 12. driver output waveform and fft plot of max1480b/max1480c/max1490b transmitting a 150khz signal 10db/div 0hz 5mhz 500khz/div _____________________ function tables half-duplex devices (max1480a/max1480b/max1480c) full-duplex devices (max1490a/max1490b) 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 max1480a/b/c, figure 2 for max1490a/b). outputs input * (di )
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface ______________________________________________________________________________________ 17 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 max1480a/b/c 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 22 f 0.1 f c1 c2 max1480a/b/c 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 max487 max1487 max845 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) figure 13. typical half-duplex rs-485/rs-422 network
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 18 ______________________________________________________________________________________ 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- cuits over the entire common-mode range (see the typical operating characteristics ). in addition, a ther- mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively. propagation delay skew typical propagation delays are shown in the typical operating characteristics using the test circuit of figure 5. propagation delay skew is simply the differ- ence between the low-to-high and high-to-low propaga- tion delay. small driver/receiver skew times help reduce emi and reflections by maintaining balanced differential signals. the receiver skew time, i t plh - t phl i , is typically under 100ns for the max1480a/max1490a and under 1? for the max1480b/max1480c/max1490b. the driver skew time is typically 25ns for the max1480a/max1490a and 100ns for the max1480b/ max1480c/max1490b. ___________ applications information di and de are intended to be driven through a series current-limiting resistor. directly grounding these pins destroys the device. the max1480a/max1480b/max1480c are designed for bidirectional data communications on multipoint bus-transmission lines. the max1490a/max1490b are designed for full-duplex bidirectional communications that are primarily point-to-point. figures 13 and 14 show half-duplex and full-duplex typical network appli- cation 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 max1480b/ max1480c/max1490b are more tolerant of imperfect termination and stubs off the main line. layout considerations the max1480a/max1480b/max1480c/max1490a/ max1490b 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 max1480a/ max1480b/max1480c/max1490a/max1490b. shield (optional) note: resistors r5 and r6 protect the max1490a/b 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 22 f 0.1 f c1 c2 max1490a/b 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 max845 max488 max490 d di ro 120 b a r figure 14. typical full-duplex rs-485/rs-422 network
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface ______________________________________________________________________________________ 19 connections and components from one side should not be located 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 max1480a/max1480b/max1480c/max1490a/ max1490b are specified and characterized using the resistor values shown in table 1 of figure 1 and table 2 of figure 2. altering the recommended values can degrade performance. the di and de (max1480a/b/c 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 resis- tor values shown in tables 1 and 2 are recommended when the 74hc86 gate or equivalent is used. these values may need to be adjusted if a driving gate with dissimilar series resistance is used. all pull-up 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 will cause the iso- lated common voltage to go to the mean voltage of the receiver inputs. if using shielded cable, connect the isolated common to the shield through a 100 resistor. in the case of the max1490, each shield should have its own 100 resistor (figures 1, 2, 13, and 14). 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 max1480c max1480c figure 15. doubly isolated rs-485 repeater
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 20 ______________________________________________________________________________________ doubly isolated rs-485 repeater the rs-422/rs-485 standard is specified for cable lengths up to 4000 feet. when approaching or exceed- ing 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 frequency, 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 currents may flow. these cur- rents are by their nature unstable and unpredictable. in addition, they may cause noise to be injected into sen- sitive instrumentation and, in severe cases, might actu- ally cause physical damage to such equipment. figure 15 shows a half-duplex (two-wire), bidirectional, party-line repeater system that prevents interference and/or damage from ground-potential differences. two max1480a/max1480b/max1480c isolated rs-485 transceivers are used to isolate each of the network segments from the electrical environment of the repeater. the max1480a/max1480b/max1480c also regenerate bus signals that may have been degraded by line attenuation or dispersion. 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 undesir- able, 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 15, 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 15 can be used either directly as shown, with the slew-rate-limited max1480b/max1480c, for data transfer rates up to 250kbps, or with the max1480a for data rates up to 2.5mbps (see table 1 for pullup and led resistor values when using the max1480a, max1480b, or max1480c). if dual-port iso- lation is not needed, one of the max1480c devices can be replaced by a max487 for 250kbps applications.
max1480a/b/c, max1490a/b complete, isolated rs-485/rs-422 data interface 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 ____________________ 21 2005 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. 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 max487 max1487 max845 isolation barrier dip top view max1480a/b/c ? data rate for ??parts is up to 2.5mbps. data rate for ??and ??parts is up to 250kbps. part ? temp range pin-package max1480b cpi 0? to +70? 28 wide plastic dip max1480bepi -40? to +85? 28 wide plastic dip max1480c cpi 0? to +70? 28 wide plastic dip max1480cepi -40? to +85? 28 wide plastic dip max1490a cpg 0? to +70? 24 wide plastic dip max1490aepg -40? to +85? 24 wide plastic dip max1490b cpg 0? to +70? 24 wide plastic dip max1490bepg -40? to +85? 24 wide plastic dip package type package code document no. 28 pdip p28m-1 21-0044 package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status.

▲Up To Search▲

Price & Availability of MAX1480BCPI

	To Download MAX1480BCPI Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .