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for free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. for small orders, phone 408-737-7600 ext. 3468. _______________general description the max1481/max1484/max1485/max1486 provide software-selectable, half-/full-duplex, low-power, slew- rate-limited, and high-speed (12mbps) rs-485/rs-422 operation in a 10-pin ?ax package?he smal - lest 10-pin package available. the software-selectable, half-/full-duplex max1485/ max1486 make obsolete the normally larger and more expensive solutions required for selectable half-/full- duplex rs-485/rs-422 operation: 1) a 14-pin, full- duplex transceiver configured via jumpers between receiver and transmitter lines, or 2) two 8-pin, half- duplex transceivers, which require an additional invert- er logic gate for software selectability. the max1481/max1484 are functionally equivalent to the industry-standard max491 and 75180, and are designed for space-constrained, full-duplex rs-422 applications. all parts contain one driver and one receiver and fea- ture a 1/8-unit-load receiver input impedance, allowing up to 256 transceivers on the bus. the max1481/ max1485 feature reduced-slew-rate drivers that mini- mize emi and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 250kbps. the max1484/max1486 driver slew rates are not limited, allowing them to transmit up to 12mbps. the max1481/max1484/max1485/max1486 draw only 300? of supply current. the max1481 has a low-power shutdown mode that reduces supply current to only 0.1?. all devices operate from a single 5v supply. drivers are output short-circuit current limited and are protected against excessive power dissipation by thermal-shutdown circuitry that places the driver outputs into a high-impedance state. the receiver input has a fail- safe feature that guarantees a logic-high output if the input is open circuit. ____________________________featur es ? 10-pin max package: smallest 10-pin package ? software-selectable half-/full-duplex operation (max1485/max1486) ? 0.1 a low-current shutdown mode (max1481) ? slew-rate limiting allows error-free data transmission (max1481/max1485) ? 12mbps high-speed operation (max1484/max1486) ? allow up to 256 transceivers on the bus ________________________applications low-power rs-422/rs-485 communications level translators hand-held equipment battery-powered equipment transceiver for emi-sensitive applications industrial-control local area networks max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in ?ax package ________________________________________________________________ maxim integrated products 1 19-1312; rev 1 ; 3/06 part max1481 cub max1481eub max1484 cub 0? to +70? -40? to +85? 0? to +70? temp range pin-package 10 ?ax 10 ?ax 10 ?ax ______________or dering infor mation ______________________________________________________________selection t able half/full duplex data rate (mbps) max1481 full 0.250 max1484 full 12 part max1485 selectable 0.250 max1486 selectable 12 slew- rate limited yes no yes no low- power shutdown driver enable yes yes no yes no yes no yes quiescent current (?) 300 300 300 300 transceivers on bus 256 256 256 256 pin- package 10 ?ax 10 ?ax 10 ?ax 10 ?ax max1484eub -40? to +85? 10 ?ax receiver enable yes yes no no max1485 cub max1485eub max1486 cub 0? to +70? -40? to +85? 0? to +70? 10 ?ax 10 ?ax 10 ?ax max1486eub -40? to +85? 10 ?ax ________________________________________________________________ maxim integrated products 1 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. max is a registered trademark of maxim integrated products, inc.
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = +5v 5%, t a = t min to t max , unless otherwise noted. typical values are at v cc = +5v and t a = +25 c.) (note 1) 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. supply voltage (v cc ) ............................................................+7v control input voltage ( re , de, h/ f ) ...........-0.3v to (v cc + 0.3v) driver input voltage (di).............................-0.3v to (v cc + 0.3v) driver output voltage (a, b, y, z) ..........................-8v to +12.5v receiver input voltage, half duplex (y, z) ............-8v to +12.5v receiver input voltage, full duplex (a, b).............-8v to +12.5v receiver output voltage (ro)....................-0.3v to (v cc + 0.3v) continuous power dissipation 10-pin max (derate 5.6mw/c above +70 c) ............444mw operating temperature ranges max148_c_ _ ......................................................0c to +70c max148_e_ _....................................................-40c to +85c storage temperature range .............................-65c to +160c lead temperature (soldering, 10sec) .............................+300c r = 50 (rs-422), figure 5 no load, figure 5 -7v v out 12v de = gnd de, di, re , h/ f de, di, re , h/ f r = 50 or 27 , figure 5 r = 50 or 27 , figure 5 r = 50 or 27 , figure 5 de = gnd, v cc = gnd or 5.25v de, di, re , h/ f conditions ma 35 250 i osd driver output short-circuit current (note 3) a -10 i o 10 output leakage (y and z) (max1481/max1484 only) ma 0.125 i in2 input current (y and z for half duplex, a and b for full duplex) a 2 i in1 input current 2.0 v od1 differential driver output 5 v 0.8 v il1 input low voltage v 2.0 v ih1 input high voltage v 0.2 ? v oc change in magnitude of common-mode voltage (note 2) v 0.2 ? v od change in magnitude of differential output voltage (note 2) v 3 v oc driver common-mode output voltage units min typ max symbol parameter de = gnd -100 i o a 125 output leakage (y and z) (max1485/max1486 only) v od2 r = 27 (rs-485), figure 5 v 1.5 5 v in = 12v v in = -7v v in = 12v v in = -7v v in = 12v v in = -7v -0.1 driver
driver input to output max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc = +5v 5%, t a = t min to t ma x , unless otherwise noted. typical values are at v cc = +5v and t a = +25 c.) (note 1) switching characteristics (max1484/max1486) (v cc = 5v 5%, t a = t min to t ma x , unless otherwise noted. typical values are at v cc = +5v and t a = +25 c.) -7v v cm 12v -7v v cm 12v i o = 4ma, v id = -200mv i o = -4ma, v id = 200mv 0.4v v o 2.4v conditions k 96 r in receiver input resistance a 1 i ozr three-state output current at receiver mv 70 ? v th receiver input hysteresis mv -200 200 v th receiver differential threshold voltage v 0.4 v ol receiver output low voltage v 3.5 v oh receiver output high voltage units min typ max symbol parameter 0v v ro v cc re = gnd, de = v cc ma 95 i osr receiver output short-circuit current a 300 600 i cc no-load supply current de = gnd, re = v cc a 0.1 10 i shdn supply current in shutdown mode (max1481 only) r diff = 54 , c l1 = c l2 = 100pf, figures 7 and 9 r diff = 54 , c l1 = c l2 = 100pf, figures 7 and 9 conditions ns 5 10 t dskew driver output skew | t dplh - t dphl | 30 60 t dplh ns 30 60 t dphl driver input to output units min typ max symbol parameter c l = 15pf, s1 closed, figures 8 and 10 c l = 100pf, s2 closed, figures 8 and 10 c l = 100pf, s1 closed, figures 8 and 10 ns 40 70 t dlz driver disable time from low ns 40 70 t dzh driver enable to output high ns 40 70 t dzl driver enable to output low mbps 12 f max maximum data rate c l = 15pf, s2 closed, figures 8 and 10 c l = 100pf, s2 closed, figures 6 and 12 c l = 100pf, s1 closed, figures 6 and 12 ns 20 50 t rzh receiver enable to output high ns 20 50 t rzl receiver enable to output low ns 40 70 t dhz driver disable time from high c l = 100pf, s2 closed, figures 6 and 12 c l = 100pf, s1 closed, figures 6 and 12 ns 20 50 t rhz receiver disable time from high ns 20 50 t rlz receiver disable time from low figures 11 and 13 ns 5 t rskd | t rplh - t rphl | differential receiver skew figures 11 and 13 ns 90 150 t rplh , t rphl receiver input to output r diff = 54 , c l1 = c l2 = 100pf, figures 7 and 9 ns 5 15 35 t dr , t df driver rise or fall time receiver supply current
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 4 _______________________________________________________________________________________ switching characteristics (max1481/max1485) (continued) (v cc = 5v 5%, t a = t min to t max , unless otherwise noted. typical values are at v cc = +5v and t a = +25 c.) note 1: all currents into the device are positive; all currents out of the device are negative. all voltages are referenced to device ground unless otherwise noted. note 2: ? v od and ? v oc are the changes in v od and v oc , respectively, when the di input changes state. note 3: maximum current level applies to peak current just prior to foldback-current limiting; minimum current level applies during current limiting. note 4: shutdown is enabled by bringing re high and de low. if the enable inputs are in this state for less than 50ns, the max1481 is guaranteed not to enter shutdown. if the enable inputs are in this state for at least 600ns, the max1481 is guaranteed to have entered shutdown. c l = 15pf, s1 closed, figures 8 and 10 c l = 100pf, s2 closed, figures 8 and 10 r diff = 54 , c l1 = c l2 = 100pf, figures 7 and 9 c l = 100pf, s1 closed, figures 8 and 10 r diff = 54 , c l1 = c l2 = 100pf, figures 7 and 9 ns 200 t dlz c l = 100pf, s2 closed, figures 6 and 12 driver disable time from low c l = 100pf, s1 closed, figures 6 and 12 r diff = 54 , c l1 = c l2 = 100pf, figures 7 and 9 ns 3000 t dzh driver enable to output high ns 3000 conditions t dzl driver enable to output low kbps 250 f max maximum data rate c l = 15pf, s2 closed, figures 8 and 10 c l = 100pf, s2 closed, figures 6 and 12 c l = 100pf, s1 closed, figures 6 and 12 ns 10 200 t dskew driver output skew | t dplh - t dphl | figures 11 and 13 ns ns 20 50 t rzh receiver enable to output high ns 20 50 t rzl receiver enable to output low ns 200 t dhz driver disable time from high ns ns 20 50 t rhz receiver disable time from high 90 150 t rplh , t rphl receiver input to output 250 1000 t dr , t df driver rise or fall time ns 20 50 t rlz receiver disable time from low figures 11 and 13 ns 15 t rskd | t rplh - t rphl | differential receiver skew 600 1000 t dplh ns 600 1000 t dphl driver input to output units min typ max symbol parameter max1481 only (note 4) ns 50 200 600 t shdn time to shutdown max1481 only, c l = 15pf, s2 closed, figures 8 and 10 ns 3000 t dzh(shdn) driver enable from shutdown to output high max1481 only, c l = 15pf, s1 closed, figures 8 and 10 ns 3000 t dzl(shdn) driver enable from shutdown to output low max1481 only, c l = 100pf, s1 closed, figures 6 and 12 ns 1000 t rzl(shdn) receiver enable from shutdown to output low max1481 only, c l = 100pf, s2 closed, figures 6 and 12 ns 500 t rzh(shdn) receiver enable from shutdown to output high
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package _______________________________________________________________________________________ 5 220 260 240 300 280 340 320 360 -60 -20 0 -40 20 40 60 80 100 no-load supply current vs. temperature max1481/4/5/6-01 temperature (?) supply current ( m a) max1481/max1485 max1484/max1486 0 10 30 20 50 40 60 0 1 2 3 4 5 output current vs. receiver output low voltage max1481/4/5/6-02 output low voltage (v) output current (ma) 0 5 15 10 25 20 30 0 1 2 3 4 5 output current vs. receiver output high voltage max1481/4/5/6-03 output low voltage (v) output current (ma) 94 98 106 102 110 114 -60 -20 0 -40 20 40 60 80 100 shutdown current vs. temperature max1481/4/5/6-04 temperature (?) shutdown current (na) 75 80 90 85 100 95 105 -60 -20 0 -40 20 40 60 80 100 max1481/max1485 receiver propagation delay vs. temperature max1481/4/5/6-07 temperature (?) propagation delay (ns) c load = 15pf 0.10 0.20 0.15 0.35 0.30 0.25 0.45 0.40 0.50 -60 -20 0 -40 20 40 60 80 100 receiver output low voltage vs. temperature max1481/4/5/6-05 temperature (?) output low voltage (v) i ro = 8ma 3.8 4.0 3.9 4.2 4.1 4.4 4.3 4.5 -60 -20 0 -40 20 40 60 80 100 receiver output high voltage vs. temperature max1481/4/5/6-06 temperature (?) output voltage (v) i ro = 8ma 86 87 90 89 88 93 92 91 94 -60 -20 0 -40 20 40 60 80 100 max1484/max1486 receiver propagation delay vs. temperature max1481/4/5/6-08 temperature (?) propagation delay (ns) c load = 15pf 540 580 560 620 600 660 640 680 -60 -20 0 -40 20 40 60 80 100 max1481/max1485 driver propagation delay vs. temperature max1481/4/5/6-09 temperature (?) propagation delay (ns) r diff = 54 w c l1 = c l2 = 100pf __________________________________________ t ypical operating characteristics (v cc = +5v, t a = +25 c, unless otherwise noted.)
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 6 _______________________________________________________________________________________ _________________________________ t ypical operating characteristics (continued) (v cc = +5v, t a = +25 c, unless otherwise noted.) 18 26 22 30 34 38 -60 -20 0 -40 20 40 60 80 100 max1484/max1486 driver propagation delay vs. temperature max1481/4/5/6-10 temperature (?) propagation delay (ns) r diff = 54 w c l1 = c l2 = 100pf 0 60 40 20 80 120 100 140 0 4 2 6 8 10 12 output current vs. driver output low voltage max1481/4/5/6-11 output low voltage (v) output current (ma) 0 40 20 60 100 80 120 -8 -4 -2 -6 0 2 4 6 output current vs. driver output high voltage max1481/4/5/6-12 output high voltage (v) output current (ma) 2.10 2.15 2.25 2.20 2.35 2.30 2.40 -60 -20 0 -40 20 40 60 80 100 driver differential output voltage vs. temperature max1481/4/5/6-13 temperature (?) output voltage (v) r diff = 54 w v a - v b ro (2v/div) (5v/div) 1 m s/div max1481/max1485 receiver propagation delay max1481/4/5/6-16 100 0.01 0 2.5 3.0 3.5 4.0 4.5 0.5 1.0 1.5 2.0 5.0 driver output current vs. differential output voltage 0.1 max1481/4/5/6-14 differential output voltage (v) output current (ma) 1 10 v a - v b ro (2v/div) (5v/div) 50ns/div max1484/max1486 receiver propagation delay max1481/4/5/6-15 di v y - v z (5v/div) (2v/div) 1 m s/div max1481/max1485 driver propagation delay max1481/4/5/6-17 di v y - v z 5v/div 2v/div 50ns/div max1484/max1486 driver propagation delay max1481/4/5/6-18
pin max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package _______________________________________________________________________________________ 7 ______________________________________________________________ pin description 1 1 receiver output. when re is low and if a - b 3 200mv, ro goes high; if a - b -200mv, ro goes low. 2 half-/full-duplex selector input. connect h/ f to v cc for half-duplex mode, and connect to gnd for full-duplex mode. 2 receiver output enable input. drive re low to enable ro; ro is high impedance when re is high. for max1481 only, drive re high and de low to enter the low- power shutdown mode. 3 3 driver output enable input. drive de high to enable driver outputs. these outputs are high impedance when de is low. 4 4 driver input. with de high, a low on di forces noninverting output low and invert - ing output high. similarly, a high on di forces noninverting output high and invert - ing output low. 5 5 ground 6 6 inverting receiver input receiver input resistors* 7 7 inverting driver output inverting driver output and inverting receiver input 8 8 noninverting driver output noninverting driver output and noninverting receiver input 9 9 noninverting receiver input receiver input resistors* 10 10 positive supply; +4.75v v cc +5.25v max1481/ max1484 1 ro 2 h/ f pin re 3 de 4 di 5 gnd b 6 b z 7 z y 8 y a 9 a 10 v cc max1485/max1486 h/ f = 0 function name h/ f = 1 * (max1485/max1486 only) in half-duplex mode, the driver outputs serve as receiver inputs. the full-duplex receiver inputs (a and b) will still have a 1/8-unit load, but are not connected to the receiver.
output inputs max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 8 _______________________________________________________________________________________ re de x 1 x 1 0 0 1 0 di z 1 0 0 1 x high-z x inputs _____________________________________________________________ function t ables transmitting y 1 0 high-z high-z and shutdown outputs max1481 max1484 max1485/max1486 re de 0 x 0 x 1 1 1 0 high-z and shutdown output a-b ro 3 0.2v 1 -0.2v 0 x high-z x inputs receiving transmitting re de y x 1 1 x 1 0 x 0 high-z outputs di z 1 0 0 1 x high-z inputs re de 0 x 0 x 1 x output a-b ro 3 0.2v 1 -0.2v 0 x high-z inputs receiving de di transmitting 1 1 1 0 0 x z y 0 1 1 0 high-z high-z outputs receiving h/ f de ro 0 x 1 0 x 0 1 0 1 output a-b y-z 3 0.2v x -0.2v x x 3 0.2v inputs 1 0 0 x -0.2v x = don? care note: in shutdown mode, driver and receiver outputs are high impedance. inputs
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package _______________________________________________________________________________________ 9 1 2 3 4 5 1 9 a r t r t 10 0.1 m f 5 gnd 6 b z 7 8 y ro re de di 2 3 4 10 9 8 7 6 v cc a y z di de re ro max1481 max1484 max1481 max1484 max1481 max1484 m max top view b gnd 8 4 10 0.1 m f 5 gnd 3 2 di de re ro 1 y z b a 7 6 9 v cc v cc figure 1. max1481/max1484 pin configuration and typical full-duplex operating circuit 1 2 3 4 5 1 9 a r t r t 10 0.1 m f v cc 5 gnd 6 b z 7 8 y ro h/f de di 2 3 4 10 9 8 7 6 v cc a y z di de h/f ro max1485 max1486 max1485 max1486 max1485 max1486 m max top view b gnd 8 4 10 0.1 m f v cc 5 gnd 3 2 di de h/f ro 1 y z b a 7 6 9 v cc v cc figure 2. max1485/max1486 pin configuration and equivalent typical full-duplex operating circuit 1 2 3 4 5 1 8 y r t 10 0.1 m f 5 gnd 7 z a 9 6 b ro h/f de di 2 3 4 10 9 8 7 6 v cc a y z di de h/f ro max1485 max1486 max1485 max1486 max1485 max1486 m max top view b gnd r t 8 4 10 0.1 m f 5 gnd 3 2 di de h/f ro 1 y z 7 9 a b 6 v cc v cc figure 3. max1485/max1486 pin configuration and equivalent typical half-duplex operating circuit
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 10 ______________________________________________________________________________________ _______________ detailed description the max1481/max1484/max1485/max1486 high- speed transceivers for rs-485/rs-422 communication contain one driver and one receiver. the max1481/ max1485 feature reduced-slew-rate drivers that mini - mize emi and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 250kbps. the max1484/max1486 driver slew rates are not limited, making transmission speeds up to 12mbps possible. these transceivers are designed to operate on a +5v single supply and typically draw 300 a of supply cur - rent when unloaded or fully loaded with the drivers dis - abled. the max1481 has a shutdown mode in which supply current is typically reduced to 0.1 a. drivers are output short-circuit current limited and are protected against excessive power dissipation by ther - mal-shutdown circuitry that places the driver outputs into a high-impedance state. all devices have a 1/8-unit-load receiver input imped - ance that allows up to 256 transceivers on the bus. the max1481/max1484 are designed for full-duplex com - munications. the h/ f pin on the max1485/max1486 allows the user to select between half-duplex or full- duplex operation (figure 4). max1485/max1486 half-/full-duplex mode operation the max1484/max1485 can operate in full- or half- duplex mode. drive the h/ f pin low or connect it to gnd for full-duplex operation, or drive it high for half- duplex operation. in full-duplex mode, the pin configu - ration of the driver and receiver is the same as a max1481 (figure 1). __________ applications infor mation 256 transceivers on the bus the standard rs-485 receiver input impedance is 12k (1-unit load), and the standard driver can drive up to 32-unit loads. the max1481/max1484/max1485/ max1486 transceivers have a 1/8-unit-load receiver input impedance (96k ), allowing up to 256 trans - ceivers to be connected in parallel on one communica - tion line. connect any combination of these devices and/or other rs-485 transceivers totaling 32-unit loads or less. reduced emi and reflections the max1481/max1485 are slew-rate limited, minimiz - ing emi and reducing reflections caused by improperly terminated cables. figure 14 shows the driver output waveform and its fourier analysis of a 20khz signal transmitted by a max1484. high-frequency harmonic components with large amplitudes are evident. figure 15 shows the same signal displayed for a max1481 transmitting under the same conditions. figure 15s high-frequency harmonic components are much lower in amplitude compared to figure 14s, significantly reducing potential emi. in general, a transmitters rise time relates directly to the length of an unterminated stub, which can be dri - ven with only minor waveform reflections. the following equation expresses this relationship conservatively: length = t rise / (10 x 1.5ns/ft) where t rise is the transmitters rise time. for example, the max1481s rise time is typically 500ns, which results in excellent waveforms with a stub length up to 33 feet. a system may work well with longer unterminated stubs, even with severe reflec - tions, if the waveform settles out before the uart samples them. figure 4. max1485/max1486 functional diagram m a x 1 4 8 5 m a x 1 4 8 6 z d i d e r o v c c g n d y b a h / f
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package ______________________________________________________________________________________ 11 r r y z v od v oc figure 5. driver dc test load receiver output test point 1k 1k s1 s2 v cc c l figure 6. receiver enable/disable timing test load di de 3v y z c l1 c l2 r diff v id figure 7. driver timing test circuit output under test 500 w s1 s2 v cc c l figure 8. driver enable/disable timing test load di 3v 0v z y v o 0v -v o v o 1.5v t dplh 1/2 v o 10% t r 90% 90% t d phl 1.5v 1/2 v o 10% t f v diff = v y - v z v diff t skew = | t plh - t phl | figure 9. driver propagation delays 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 dzl(shdn) , t dpl t d lz d zh(shdn) , d zh d hz de figure 10. driver enable and disable times
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 12 ______________________________________________________________________________________ low-power shutdown mode (max1481 only) low-power shutdown mode is initiated by bringing both re high and de low. in shutdown, the max1481 typi - cally draws only 0.1 a 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 state for at least 600ns, the parts are guaranteed to enter shutdown. enable times t_ zh and t_ z l in the switching character- istics tables assume the part was not in low-power shut - down. enable times t_ zh (shdn) and t_ zl (shdn) assume the parts were shut down. it takes drivers and receivers longer to become enabled from the low-power shutdown mode (t_ zh (shdn) , t_ z l(shdn) ) than from the driver/receiver disable mode (t_ zh , t_ z l ). driver output protection excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. a foldback current limit on the output stage provides immediate protection against short cir - cuits over the whole common-mode voltage range (see typical operating characteristics ). in addition, a ther - mal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature becomes excessive. v oh v ol a b 1v -1v 1.5v 1.5v output input ro r plh r phl figure 11. receiver propagation delays output normally low output normally high 3v 0v v cc ro ro 0v 1.5v 1.5v v ol + 0.5v v oh - 0.5v 1.5v 1.5v r zl(shdn) , r zl r lz r zh(shdn) , r zh r hz re figure 12. receiver enable and disable times (max1481/max1484 only) r b receiver output ate a v id r figure 13. receiver propagation delay test circuit 20db/div 250khz/div 2.5mhz 0hz max1481/4/5/6-fig14 figure 14. driver output waveform and fft plot of max1484/max1486 transmitting a 20khz signal
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package ______________________________________________________________________________________ 13 line length vs. data rate the rs-485/rs-422 standard covers line lengths up to 4000 feet. for line lengths greater than 4000 feet, use the repeater application shown in figure 16. figures 17 and 18 show the system differential voltage for the parts driving 4000 feet of 26awg twisted-pair wire into 120 loads. typical applications the max1485/max1486 are designed for bidirectional data communications on multipoint bus transmission lines. figures 19 and 20 show typical network applica - tions circuits. these parts can also be used as line repeaters with cable lengths longer than 4000 feet (figure 16). to minimize reflections, terminate the line at both ends in its characteristic impedance, and keep stub lengths off the main line as short as possible. the slew-rate-lim - ited max1481/max1485 are more tolerant of imperfect termination than the max1484/max1486. 20db/div 250khz/div 2.5mhz 0hz max1481/4/5/6-fig15 figure 15. driver output waveform and fft plot of max1481/max1485 transmitting a 20khz signal 120 w 120 w data in data out r d ro re de di h/f a b z y max1481 max1484 max1485 max1486 note: re on max1481 and max1484 only. h/f on max1485 and max1486 only. figure 16. line repeater v a - v b di ro 5v/div 5v/div 4v/div 5 m s/div max1481/4/5/6-fig17 figure 17. max1481/max1485 system differential voltage at 50khz driving 4000 ft. of unterminated cable v a - v b di ro 5v/div 5v/div 4v/div 1 m s/div max1481/4/5/6-fig18 figure 18. max1484/max1486 system differential voltage at 200khz driving 4000 ft. of unterminated cable
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 14 ______________________________________________________________________________________ figure 19. typical half-duplex rs-485 network di r o de z ro ro ro di di di de de de d d d r r r z z (z) (y ) y y y 120 w 120 w d r m a x 1 4 8 5 m a x 1 4 8 6 v cc 5v h/f v cc 5v h/f v cc 5v v cc v cc h/f
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package ______________________________________________________________________________________ 15 120 w 120 w r d ro de di a b y re* re* 120 w 120 w di di diro ro ro de de de re re* z z z z y y y a a a b b b d d d r r r max1481 max1484 max1485 max1486 *re on max1481 and max1484 only. **h/f on max1485 and max1486 only. h/f** h/f** h/f** h/f** figure 20. typical full-duplex rs-485 network ___________________ chip infor mation transistor count: 396
max1481/max1484/max1485/max1486 softwar e-selectable, half-/full-duplex, slew-rate-limited, 12mbps, rs-485/rs-422 t ransceivers in max package 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. 16 ____________________ maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ? 2006 maxim integrated products printedsa is a registered trademark of maxim integrated products , inc. ________________________________________________________ package infor mation 10lumaxb.eps package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .)

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