low-power, slew-rate-limited rs-485/rs-422 transceivers description the sn75176 is low-power transceivers for rs-485 and rs- 422 communica tion. ic contains one driver and one receiver. the driver slew rates of the sn75176 is not limited, allowing them to tran smit up to 10 mbps. these transceivers draw between 120a and 500a of supply current when unloaded or fully loaded with disabled drivers. all parts opera te from a single 5v supply. drivers are short-circuit current limited and are protected against excessive power dissi pation by thermal shutdown circuitry that places the dr iver 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. the sn75176 is designed for half-duplex applications. sn75176bp dip8 SN75176BDR sop8 features ? low quiescent current: 300a ? -7v to +12v common-mode input voltage range ? three-state outputs ? 50ns propagation delays, 5ns skew ? full-duplex and half-duplex versions available ? operate from a single 5v supply ? allows up to 32 transceivers on the bus ? data rate: 10 mbps ? current-limiting and thermal shutdown for driver overload protection ? enhanced esd specifications: 15kv iec61000-4-2 air discharge 8kv iec61000-4-2 contact discharge pin description tiger electronic co.,ltd
75176 absolute maximum ratings supply voltage (v cc ) 12v continuous power dissipation (t a = +70c) control input voltage -0.5v to (v cc + 0.5v) 8-pin plastic dip (derate 9.09mw/c above +70c) 727mw driver input voltage (di) -0.5v to (v cc + 0.5v) 8-pin sop (derate 5.88mw/c above +70c) 471mw driver output voltage (a, b) -8v to +12.5v operating temperature ranges 0c to +70c receiver input voltage (a, b) -8v to +12.5v storage temperature range -65c to +150c receiver output voltage (ro) -0.5v to (v cc +0.5v) lead temperature (soldering, 10sec) +260c * stresses beyond those listed under ?absolute maximu m ratings? may cause permanent damage to the device. these are stress ratings only and functional operation of th e device at these or any other conditions beyond those indicated under ?recommended operating conditions? is not implied. exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. dc electrical characteristics (v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) parameter symbol conditions min ty p max unit s differential driver output (no load) v od1 5 v differential driver output (with load) v od2 r = 50 ? 2 v r = 27 ? 1.5 5 change in magnitude of driver differential output voltage for complementary output states ? r = 27 ? ? 0.2 v driver common-mode output voltage v oc r = 27 ? ? 3 v change in magnitude of driver common-mode output voltage for complementary output states ? r = 27 ? ? 0.2 v input high voltage v ih de, di, re 2.0 v input low voltage v il de, di, re 0.8 v input current i in1 de, di, re 2 a input current (a, b) i in2 de = 0v; v cc = 0v or 5.25v v in = 12v 1.0 ma v in = -7v -0.8 receiver differential threshold voltage v th -7v -0.2 0.2 v receiver input hysteresis ? v cm = 0v 70 mv receiver output high voltage v oh i o = -4ma, vid = 200mv 3.5 v receiver output low voltage v ol i o = 4ma, vid = -200mv 0.4 v
parameter symbol conditions min typ max units driver input to output t plh r diff = 54 10 55 60 ns t phl c l1 = c l2 = 100pf 10 55 60 driver output skew to output t skew r diff = 54 5 10 ns driver enable to output high t zh c l = 100pf, s2 closed 40 70 ns driver enable to output low t zl c l = 100pf, s1 closed 40 70 ns driver disable time from low t lz c l = 15pf, s1 closed 40 70 ns driver disable time from high t hz c l = 15pf, s2 closed 40 70 ns receiver input to output t plh r diff = 54 20 60 100 ns t 20 60 100 | t plh - t phl | differential receiver skew t skd r diff = 54 5 10 ns receiver enable to output low t zl c rl = 15pf, s1 closed 30 50 ns receiver enable to output high t zh c rl = 15pf, s2 closed 30 50 ns receiver disable time from low t lz c rl = 15pf, s1 closed 30 50 ns receiver disable time from high t hz c rl = 15pf, s2 closed 30 50 ns maximum data rate f max 2.5 10 20 mbps 75176 dc electrical characteristics (continue) (vcc = 5v 5%, ta = tmin to tmax, unless otherwise noted.) (notes 1, 2) parameter symbol conditions min typ max units three-state (high impedance) output current at receiver iozr 0.4v 1 a receiver input resistance rin -7v 12 k ? no-load supply current (note 3) i cc de = v cc 500 900 re = 0v or v cc 300 500 a de = 0v driver short-circuit current i osd1 -7v 35 250 ma vo = high driver short-circuit current i osd2 -7v 35 250 ma vo = low receiver short-circuit current i osr 0v 7 95 ma esd protection a, b, y and z pins, tested using human body model kv switching characteristics (v cc = 5v 5%, t a = t min to t max , unless otherwise noted.) (notes 1, 2) phl l1 l2 note 1: all currents into device pins ar e positive; all currents out of device pins are negative. all voltages are referenced to device ground unless otherwise specified. note 2: all typical specifications are given for v cc =5v and t a =+25c. note 3: supply current spec ification is valid for loaded transmitters when de=0v. note 4: applies to peak current.
75176 test circuits figure 1. driver v od and v oc figure 2. driver v od with varying common-mode voltage figure 3. receiver v oh and v ol figure 4. driver differential output delay and transition times
75176 test circuits figure 5. driver propagation times figure 6. driver enable and disable times (t pzh , t psh , t phz ) figure 7. driver enable and disable times (t pzl , t psl , t plz )
75176 test circuits figure 8. receiver propagation delay figure 9. receiver enable and disable times note 5: the input pulse is supplied by a generator with the following characteristics: prr = 250khz, 50% duty cycle, tr ? note 6: c l includes probe and stray capacitance.
receiving inputs outputs re de a-b ro 0 0 +0.2v 1 0 0 -0.2v 0 0 0 open 1 1 0 x z 75176 function tables transmitting inputs outputs x re de di z y x 1 1 0 1 x 1 0 1 0 0 0 x z z 1 0 x z z x-don?t care z-high impedance typical information figure 10. sn75176 typical rs-485 network 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 prov ides immediate protection agai nst short circuits over the whole common-mode voltage range. in addition, a thermal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively. propagation delay skew time is simply the difference between t he low-to-high and high-to-low propagation delay. small driver/receiver skew times help maintain a sy mmetrical mark-space ratio (50% duty cycle). the receiver skew time, | t prlh - t prhl | , is under 10ns. the driver skew times are 5ns for the sn75176. typical applications sn75176 transceivers are designed for bi directional data communications on multipoint bus transmission lines. figure 10 shows typical network applications circuits. these parts can also be used as line repeaters , with cable lengths longer than 4000 feet. to minimize reflections, the line should be terminated at both ends in its characte ristic impedance, and stub lengths off the main line should be kept as short as possible.
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