View LTC485MJ8TRPBF_6984084.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

ltc485 1 485fh typical application description low power rs485 interface transceiver the ltc ? 485 is a low power differential bus/line trans- ceiver designed for multipoint data transmission standard rs485 applications with extended common mode range (12v to C7v). it also meets the requirements of rs422. the cmos design offers signi? cant power savings over its bipolar counterpart without sacri? cing ruggedness against overload of esd damage. the driver and receiver feature three-state outputs, with the driver outputs maintaining high impedance over the entire common mode range. excessive power dissipa- tion caused by bus contention or faults is prevented by a thermal shutdown circuit which forces the driver outputs into a high impedance state. the receiver has a fail-safe feature which guarantees a high output state when the inputs are left open. the ltc485 is fully speci? ed over the commercial and extended industrial temperature range. driver outputs features applications n low power: i cc = 300a typ n designed for rs485 interface applications n single 5v supply n C7v to 12v bus common mode range permits 7v ground difference between devices on the bus n thermal shutdown protection n power-up/down glitch-free driver outputs permit live insertion or removal of transceiver n driver maintains high impedance in three-state or with the power off n combined impedance of a driver output and receiver allows up to 32 transceivers on the bus n 70mv typical input hysteresis n 30ns typical driver propagation delays with 5ns skew for up to 2.5mb operation n pin compatible with 60v protected lt1785 and 52mbps ltc1685 n low power rs485/rs422 transceiver n level translator l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. v cc1 gnd1 r ro1 re 1 de1 di1 d v cc2 gnd2 r ro2 re 2 de2 di2 d rt rt 485 ta01a 485 ta01b a b
ltc485 2 485fh pin configuration absolute maximum ratings supply voltage ..........................................................12v control input voltages .....................C0.5v to v cc + 0.5v driver input voltage .........................C0.5v to v cc + 0.5v driver output voltage ..............................................14v receiver input voltage ............................................14v receiver output voltages ................ C0.5v to v cc + 0.5v operating temperature range ltc485i..........................................C40c t a 85c ltc485c ............................................0c t a 70c ltc485m......................................C55c t a 125c lead temperature (soldering, 10 sec) .................. 300c (note 1) n8 package 8-lead plastic dip 1 2 3 4 8 7 6 5 top view v cc b a gnd s8 package 8-lead plastic soic r d ro re de di j8 package 8-lead ceramic dip t jmax = 125c, ja = 100c/w (n) t jmax = 150c, ja = 150c/w (s) t jmax = 155c, ja = 100c/w (j) order information lead free finish tape and reel part marking* package description temperature range ltc485cn8#pbf ltc485cn8#trpbf ltc485cn8 8-lead plastic dip 0c to 70c ltc485cs8#pbf ltc485cs8#trpbf 485 8-lead plastic soic 0c to 70c ltc485in8#pbf ltc485in8#trpbf ltc485in8 8-lead plastic dip C40c to 85c ltc485is8#pbf ltc485is8#trpbf 485i 8-lead plastic soic C40c to 85c ltc485mj8#pbf ltc485mj8#trpbf ltc485mj8 8-lead ceramic dip C55c to 125c lead based finish tape and reel part marking* package description temperature range ltc485cn8 ltc485cn8#tr ltc485cn8 8-lead plastic dip 0c to 70c ltc485cs8 ltc485cs8#tr 485 8-lead plastic soic 0c to 70c ltc485in8 ltc485in8#tr ltc485in8 8-lead plastic dip C40c to 85c ltc485is8 ltc485is8#tr 485i 8-lead plastic soic C40c to 85c ltc485mj8 ltc485mj8#tr ltc485mj8 8-lead ceramic dip C55c to 125c consult ltc marketing for parts speci? ed with wider operating temperature ranges. *the temperature grade is identi? ed by a label on the shipping container. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel speci? cations, go to: http://www.linear.com/tapeandreel/ symbol parameter conditions min typ max units v od1 differential driver output voltage (unloaded) i o = 0 l 5v v od2 differential driver output voltage (with load) r = 50 (rs422) r = 27 (rs485), figure 1 l l 2 1.5 5 v v v od change in magnitude of driver differential output voltage for complementary states r = 27 or r = 50, figure 1 l 0.2 v v oc driver common mode output voltage r = 27 or r = 50, figure 1 l 3v |v oc | change in magnitude of driver common mode output voltage for complementary states r = 27 or r = 50, figure 1 l 0.2 v electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cc = 5v 5%, unless otherwise noted. (notes 2 and 3)
ltc485 3 485fh electrical characteristics note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: all currents into device pins are positive; all currents out ot device pins are negative. all voltages are referenced to device ground unless otherwise speci? ed. the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cc = 5v 5%, unless otherwise noted. (notes 2 and 3) switching characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cc = 5v 5%, unless otherwise noted. (notes 2 and 3) symbol parameter conditions min typ max units i cc supply current no load, pins 2, 3, 4 = 0v or 5v outputs enabled outputs disabled l l 500 300 900 500 a a i osd1 driver short-circuit current, v out = high v o = C 7v l 35 100 250 ma i osd2 driver short-circuit current, v out = low v o = 10v l 35 100 250 ma i osr receiver short-circuit current 0v v o v cc l 7 85 ma t plh driver input to output r diff = 54, c l1 = c l2 = 100pf, (figures 3 and 5) l 10 30 50 ns t phl driver input to output l 10 30 50 ns t skew driver output to output l 510 ns t r , t f driver rise or fall time l 31525 ns t zh driver enable to output high c l = 100pf (figures 4 and 6) s2 closed l 40 70 ns t zl driver enable to output low c l = 100pf (figures 4 and 6) s1 closed l 40 70 ns t lz driver disable time from low c l = 15pf (figures 4 and 6) s1 closed l 40 70 ns t hz driver disable time from high c l = 15pf (figures 4 and 6) s2 closed l 40 70 ns t plh receiver input to output r diff = 54, cl1 = cl2 = 100pf, (figures 3 and 7) l 30 90 200 ns t phl l 30 90 200 ns t skd |t plh C t phl | differential receiver skew l 13 ns t zl receiver enable to output low c rl = 15pf (figures 2 and 8) s1 closed l 20 50 ns t zh receiver enable to output high c rl = 15pf (figures 2 and 8) s2 closed l 20 50 ns t lz receiver disable from low c rl = 15pf (figures 2 and 8) s1 closed l 20 50 ns t hz receiver disable from high c rl = 15pf (figures 2 and 8) s2 closed l 20 50 ns symbol parameter conditions min typ max units v ih input high voltage de, di, re l 2v v il input low voltage de, di, re l 0.8 v i in1 input current de, di, re l 2 a i in2 input current (a, b) de = 0, v cc = 0v or 5.25v v in = 12v v in = C7v l l 1 C0.8 ma ma v th differential input threshold voltage for receiver C7v v cm 12v l C0.2 0.2 v v th receiver input hysteresis v cm = 0v l 70 mv v oh receiver output high voltage i o = C4ma, v id = 200mv l 3.5 v v ol receiver output low voltage i o = 4ma, v id = C200mv l 0.4 v i ozr three-state (high impedance) output current at receiver v cc = max, 0.4v v o 2.4v l 1 a r in receiver input resistance C7v v cm 12v l 12 k note 3: all typicals are given for v cc = 5v and t a = 25c. note 4: the ltc485 is guaranteed by design to be functional over a supply voltage range of 5v 10%. data sheet parameters are guaranteed over the tested supply voltage range of 5v 5%.
ltc485 4 485fh typical performance characteristics receiver output low voltage vs temperature driver differential output voltage vs output current driver differential output voltage vs temperature driver output low voltage vs output current driver output high voltage vs output current ttl input threshold vs temperature receiver output low voltage vs output current receiver output high voltage vs output current receiver output high voltage vs temperature output voltage (v) 0 0 output current (ma) 4 12 16 20 1.0 36 485 g01 8 0.5 2.0 24 28 32 1.5 t a = 25c output voltage (v) 5 0 output current (ma) C2 C6 C8 C10 3 C18 485 g02 C4 4 C12 C14 C16 2 t a = 25c temperature (c) C50 3.0 output voltage (v) 3.2 3.6 3.8 4.0 75 4.8 485 g03 3.4 0 125 4.2 4.4 4.6 C25 25 50 100 i = 8ma temperature (c) C50 0 output voltage (v) 0.1 0.3 0.4 0.5 75 0.9 485 g04 0.2 0 125 0.6 0.7 0.8 C25 25 50 100 i = 8ma output voltage (v) 0 0 output current (ma) 8 24 32 40 2 72 485 g05 16 13 48 56 64 4 t a = 25c temperature (c) C50 1.5 differential voltage (v) 1.6 1.8 1.9 2.0 75 2.4 485 g06 1.7 0 125 2.1 2.2 2.3 C25 25 50 100 ri = 54 output voltage (v) 0 0 output current (ma) 10 30 40 50 2 90 485 g07 20 13 60 70 80 4 t a = 25c output voltage (v) 0 0 output current (ma) C12 C36 C48 C60 2 C108 485 g08 C24 13 C72 C84 C96 4 t a = 25c temperature (c) C50 1.55 input threshold voltage (v) 1.56 1.58 1.59 1.60 75 1.64 485 g09 1.57 0 125 1.61 1.62 1.63 C25 25 50 100
ltc485 5 485fh typical performance characteristics receiver |t plh C t phl | vs temperature driver skew vs temperature supply current vs temperature temperature (c) C50 3.0 time (ns) 3.5 4.5 5.0 5.5 75 7.5 485 g10 4.0 0 125 6.0 6.5 7.0 C25 25 50 100 temperature (c) C50 0 time (ns) 0.6 1.8 2.4 3.0 75 5.4 485 g11 1.2 0 125 3.6 4.2 4.8 C25 25 50 100 temperature (c) C50 100 supply current (a) 160 280 340 400 75 640 485 g12 220 0 125 460 520 580 C25 25 50 100 driver enabled driver disabled pin functions ro (pin 1): receiver output. if the receiver output is en- abled ( re low), then if a > b by 200mv, ro will be high. if a < b by 200mv, then ro will be low. re (pin 2): receiver output enable. a low enables the receiver output, ro. a high input forces the receiver output into a high impedance state. de (pin 3): driver outputs enable. a high on de enables the driver output. a and b, and the chip will function as a line driver. a low input will force the driver outputs into a high impedance state and the chip will function as a line receiver. di (pin 4): driver input. if the driver outputs are enabled (de high), then a low on di forces the outputs a low and b high. a high on di with the driver outputs enabled will force a high and b low. gnd (pin 5): ground connection. a (pin 6): driver output/receiver input. b (pin 7): driver output/receiver input. v cc (pin 8): positive supply; 4.75 < v cc < 5.25.
ltc485 6 485fh switching time waveforms test circuits v od a b r r v oc 485 f01 figure 1. driver dc test load figure 2. receiver timing test load figure 3. driver/receiver timing test circuit figure 4. driver timing test load #2 receiver output c rl 15pf 1k s1 s2 test point v cc 1k 485 f02 3v de a b di r diff c l1 c l2 ro 15pf a b re 485 f03 output under test c l s1 s2 v cc 500 7 485 f04 figure 5. driver propagation delays di 3v 1.5v t plh t r t skew 1/2 v o v o 80% 10% 0v b a v o Cv o 0v 90% 1.5v t plh t skew 1/2 v o f = 1mhz, t r 10ns, t f 10ns 20% t f v diff = v(a) C v(b) 485 f05
ltc485 7 485fh switching time waveforms figure 6. driver enable and disable times 1.5v t zl 2.3v 2.3v t zh 1.5v t lz 0.5v 0.5v t hz f = 1mhz, t r 10ns, t f 10ns output normally low output normally high 3v 0v di 5v v ol v oh 0v a, b a, b 485 f06 figure 7. receiver propagation delays 1.5v t phl f = 1mhz, t r 10ns, t f 10ns r Cv od2 a, b 0v 1.5v t plh output input v od2 v ol v oh 485 f07 figure 8. receiver enable and disable times 1.5v t zl 1.5v 1.5v t zh 1.5v t lz 0.5v 0.5v t hz f = 1mhz, t r 10ns, t f 10ns output normally low output normally high 3v 0v re 5v 0v r r 485 f08 function tables ltc485 transmitting inputs line condition outputs re de di b a 1 1 n ft 0 1 1 0 n ft 1 0 0 1 ft ltc485 receiving inputs outputs re de a C b r 0 0 0.2v 1 0 0 C0.2v 0 0 0 inputs open 1 10xz
ltc485 8 485fh basic theory of operation previous rs485 transceivers have been designed using bipolar technology because the common mode range of the device must extend beyond the supplies and the device must be immune to esd damage and latchup. unfortunately, the bipolar devices draw a large amount of supply current, which is unacceptable for the numerous applications that require low power consumption. the ltc485 is the ? rst cmos rs485/rs422 transceiver which features ultralow power consumption without sacri? cing esd and latchup immunity. the ltc485 uses a proprietary driver output stage, which allows a common-mode range that extends beyond the power supplies while virtually eliminating latchup and providing excellent esd protection. figure 9 shows the ltc485 output stage while figure 10 shows a conventional cmos output stage. when the conventional cmos output stage of figure 10 enters a high impedance state, both the p-channel (p1) and the n-channel (n1) are turned off. if the output is then driven above v cc or below ground, the p + /n-well diode figure 9. ltc485 output stage (d1) or the n + /p-substrate diode (d2) respectively will turn on and clamp the output to the supply. thus, the output stage is no longer in a high impedance state and is not able to meet the rs485 common mode range requirement. in addition, the large amount of current ? owing through either diode will induce the well known cmos latchup condition, which could destroy the device. the ltc485 output stage of figure 9 eliminates these problems by adding two schottky diodes, sd3 and sd4. the schottky diodes are fabricated by a proprietary modi- ? cation to the standard n-well cmos process. when the output stage is operating normally, the schottky diodes are forward biased and have a small voltage drop across them. when the output is in the high impedance state and is driven above v cc or below ground, the parasitic diodes d1 or d2 still turn on, but sd3 or sd4 will reverse bias and prevent current from ? owing into the n-well or the substrate. thus, the high impedance state is maintained even with the output voltage beyond the supplies. with no minority carrier current ? owing into the n-well or substrate, latchup is virtually eliminated under power-up or power-down conditions. applications information figure 10. conventional cmos output stage logic v cc sd3 p1 d1 output sd4 d2 n1 485 f09 logic v cc p1 d1 output d2 n1 485 f10
ltc485 9 485fh applications information the ltc485 output stage will maintain a high impedance state until the breakdown of the n-channel or p-channel is reached when going positive or negative respectively. the output will be clamped to either v cc or ground by a zener voltage plus a schottky diode drop, but this voltage is way beyond the rs485 operating range. this clamp protects the mos gates from esd voltages well over 2000v. because the esd injected current in the n-well or substrate consists of majority carriers, latchup is prevented by careful layout techniques. propagation delay many digital encoding schemes are dependent upon the difference in the propagation delay times of the driver and the receiver. using the test circuit of figure 13, figures 11 and 12 show the typical ltc485 receiver propagation delay. the receiver delay times are: |t plh C t phl | = 9ns typ, v cc = 5v the driver skew times are: skew = 5ns typ, v cc = 5v 10ns max, v cc = 5v, t a = C40c to 85c figure 11. receiver t phl 485 f11 driver outputs receiver outputs a b ro figure 12. receiver t plh 485 f12 driver outputs receiver outputs a b ro figure 13. receiver propagation delay test circuit d r receiver out r 100 100pf 100pf ttl in t r , t f < 6ns br 485 f13
ltc485 10 485fh ltc485 line length vs data rate the maximum line length allowable for the rs422/rs485 standard is 4000 feet. applications information figures 17 and 18 show that the ltc485 is able to com- fortably drive 4000 feet of wire at 110khz. figure 14. line length test circuit figure 16. system differential voltage at 19.2khz figure 17. system common mode voltage at 110khz 485 f15 common mode voltage (a + b)/2 ro di 485 f16 differential voltage a C b ro di 485 f17 common mode voltage (a + b)/2 ro di figure 18. system differential voltage at 110khz figure 19. cable length vs maximum data rate 485 f18 common mode voltage (a C b) ro di maximum data rate 10k 10 cable length (ft) 100 1k 10k 100k 1m 10m 485 f19 2.5m figure 15. system common mode voltage at 19.2khz ttl out ltc485 ltc485 noise generator 100 c d 4000 ft 26awg twisted pair a b ttl in 485 f14 when specifying line length vs maximum data rate the curve in figure 19 should be used. using the test circuit in figure 14, figures 15 and 16 show that with ~20v p-p common mode noise injected on the line, the ltc485 is able to reconstruct the data stream at the end of 4000 feet of twisted pair wire.
ltc485 11 485fh typical application typical rs485 network r t 485 ta02 r t package description j8 package 8-lead cerdip (narrow .300 inch, hermetic) (reference ltc dwg # 05-08-1110) j8 0801 .014 ?.026 (0.360 ?0.660) .200 (5.080) max .015 ?.060 (0.381 ?1.524) .125 3.175 min .100 (2.54) bsc .300 bsc (7.62 bsc) .008 ?.018 (0.203 ?0.457) 0 ?15 .005 (0.127) min .405 (10.287) max .220 ?.310 (5.588 ?7.874) 12 3 4 87 65 .025 (0.635) rad typ .045 ?.068 (1.143 ?1.650) full lead option .023 ?.045 (0.584 ?1.143) half lead option corner leads option (4 plcs) .045 ?.065 (1.143 ?1.651) note: lead dimensions apply to solder dip/plate or tin plate leads
ltc485 12 485fh package description n8 package 8-lead pdip (narrow .300 inch) (reference ltc dwg # 05-08-1510) n8 1002 .065 (1.651) typ .045 ?.065 (1.143 ?1.651) .130 .005 (3.302 0.127) .020 (0.508) min .018 .003 (0.457 0.076) .120 (3.048) min 12 3 4 87 6 5 .255 .015* (6.477 0.381) .400* (10.160) max .008 ?.015 (0.203 ?0.381) .300 ?.325 (7.620 ?8.255) .325 +.035 ?015 +0.889 0.381 8.255 () note: 1. dimensions are inches millimeters *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .010 inch (0.254mm) .100 (2.54) bsc
ltc485 13 485fh information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description s8 package 8-lead plastic small outline (narrow .150 inch) (reference ltc dwg # 05-08-1610) .016 ?.050 (0.406 ?1.270) .010 ?.020 (0.254 ?0.508) 45 0 ?8 typ .008 ?.010 (0.203 ?0.254) so8 0303 .053 ?.069 (1.346 ?1.752) .014 ?.019 (0.355 ?0.483) typ .004 ?.010 (0.101 ?0.254) .050 (1.270) bsc 1 2 3 4 .150 ?.157 (3.810 ?3.988) note 3 8 7 6 5 .189 ?.197 (4.801 ?5.004) note 3 .228 ?.244 (5.791 ?6.197) .245 min .160 .005 recommended solder pad layout .045 .005 .050 bsc .030 .005 typ inches (millimeters) note: 1. dimensions in 2. drawing not to scale 3. these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006" (0.15mm)
ltc485 14 485fh linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 1994 lt 0609 rev h ? printed in usa related parts part number description comments ltc486/ltc487 low power quad rs485 drivers 110a supply current ltc488/ltc489 low power quad rs485 receivers 7ma supply current ltc490/ltc491 low power full-duplex rs485 transceivers 300a supply current ltc1480 3.3v supply rs485 transceiver lower supply voltage ltc1481 low power rs485 transceiver with shutdown lowest power ltc1482 rs485 transceiver with carrier detect 15kv esd, fail-safe ltc1483 low power, low emi rs485 transceiver slew rate limited driver outputs, lowest power ltc1484 rs485 transceiver with fail-safe 15kv esd, msop package ltc1485 10mbps rs485 transceiver high speed ltc1518/ltc1519 52mbps quad rs485 receivers higher speed, ltc488/ltc489 pin-compatible ltc1520 lvds-compatible quad receiver 100mv threshold, low channel-to-channel skew ltc1535 2500v isolated rs485 transceiver full-duplex, self-powered using external transformer ltc1685 52mbps rs485 transceiver industry-standard pinout, 500ps propagation delay skew ltc1686/ltc1687 52mbps full-duplex rs485 transceivers ltc490/ltc491 pin compatible ltc1688/ltc1689 100mbps quad rs485 drivers highest speed, ltc486/ltc487 pin compatible ltc1690 full-duplex rs485 transceiver with fail-safe 15kv esd, ltc490 pin compatible lt1785/ltc1785a 60v protected rs485 transceivers 15kv esd, fail-safe (lt1785a) lt1791/ltc1791a 60v protected full-duplex rs485 transceivers 15kv esd, fail-safe (lt1791a) ltc2850/ltc2851/ ltc2852 3.3v supply rs485 transceivers 15kv esd, 20mbps, 900a supply current, fail-safe ltc2854/ltc2855 3.3v supply rs485 transceivers 15kv esd, 20mbps, 900a supply current, integrated switchable termination ltc2856/ltc2857/ ltc2858 20mbps rs485 transceivers 15kv esd, 900a supply current, fail-safe ltc2859/ltc2861 20mbps rs485 transceivers 15kv esd, 900a supply current, integrated switchable termination

▲Up To Search▲

Price & Availability of LTC485MJ8TRPBF

	To Download LTC485MJ8TRPBF Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .