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ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 1 285678fb typical application features applications description 20mbps and slew rate limited 15kv rs485/rs422 transceivers the ltc ? 2856-1, ltc2856-2, ltc2857-1, ltc2857-2, ltc2858-1 and ltc2858-2 are low power, rs485/rs422 transceivers operating on 5v supplies at maximum data rates of 20mbps or 250kbps for low emi. the receiver has a one-eighth unit load, supporting up to 256 nodes per bus, and a failsafe feature that guarantees a high output state under conditions of ?oating or shorted inputs. the driver maintains a high output impedance over the entire common mode range when disabled or when the supply is removed. excessive power dissipation caused by bus contention or a fault is prevented by current limiting all outputs and by thermal shutdown. enhanced esd protection allows these parts to withstand 15kv (human body model) on the transceiver interface pins without latchup or damage. 20mbps or low emi 250kbps maximum data rate no damage or latchup to esd: 15kv hbm high input impedance supports 256 nodes guaranteed failsafe receiver operation over the entire common mode range current limited drivers and thermal shutdown delayed micropower shutdown: 5a maximum power up/down glitch-free driver outputs low operating current: 900a maximum in receive mode compatible with tia/eia-485-a speci?cations available in 8-lead and 10-lead 3mm 3mm dfn and 8-lead and 10-lead msop packages low power rs485/rs422 transceiver level translator backplane transceiver v cc1 gnd1 r ro1 re1 de1 di1 d r t ltc2856-1 ltc2856-1 r t 285678 ta01a v cc2 gnd2 r ro2 re2 de2 di2 d product selection guide part number max data rate (mbps) duplex package ltc2856-1 20 half msop-8, dfn-8 ltc2856-2 0.25 half msop-8, dfn-8 ltc2857-1 20 full msop-8, dfn-8 ltc2857-2 0.25 full msop-8, dfn-8 ltc2858-1 20 full msop-10, dfn-10 ltc2858-2 0.25 full msop-10, dfn-10 , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. di y z y- z 20ns/div 2856 t a01b 2v/div ltc2858-1 at 20mbps
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 2 285678fb package/order information absolute maximum ratings supply voltage (v cc ) ................................... C0.3v to 7v logic input voltages (re, de, di) ................ C0.3v to 7v interface i/o (a, b, y, z) .................... (v cc C 15v) to 15v receiver output voltage (ro) ....... C0.3v to (v cc + 0.3v) operating temperature range (note 4) ltc28xxc ................................................. 0c to 70c ltc28xxi .............................................. C40c to 85c (note 1) top view 9 dd package 8-lead (3mm 3mm) plastic dfn 5 6 7 8 4 3 2 1 ro re de di v cc b a gnd exposed pad (pin 9) is gnd, must be soldered to pcb t jmax = 125c, ja = 43c/w, jc = 3c/w 1 2 3 4 ro re de di 8 7 6 5 v cc b a gnd top view ms8 package 8-lead plastic msop t jmax = 125c, ja = 200c/w, jc = 40c/w top view 9 dd package 8-lead (3mm 3mm) plastic dfn 5 6 7 8 4 3 2 1 v cc ro di gnd a b z y exposed pad (pin 9) is gnd, must be soldered to pcb t jmax = 125c, ja = 43c/w, jc = 3c/w order part number dd part marking* order part number ms8 part marking* order part number dd part marking* ltc2856cdd-1 ltc2856idd-1 ltc2856cdd-2 ltc2856idd-2 lcmg lcmg lcmj lcmj ltc2856cms8-1 ltc2856ims8-1 ltc2856cms8-2 ltc2856ims8-2 ltcmf ltcmf ltcmh ltcmh ltc2857cdd-1 ltc2857idd-1 ltc2857cdd-2 ltc2857idd-2 lcmd lcmd lcmm lcmm 1 2 3 4 v cc ro di gnd 8 7 6 5 a b z y top view ms8 package 8-lead plastic msop t jmax = 125c, ja = 200c/w, jc = 40c/w top view 11 dd package 10-lead (3mm 3mm) plastic dfn 10 9 6 7 8 4 5 3 2 1 v cc a b z y ro re de di gnd exposed pad (pin 11) is gnd, must be soldered to pcb t jmax = 125c, ja = 43c/w, jc = 3c/w 1 2 3 4 5 ro re de di gnd 10 9 8 7 6 v cc a b z y top view ms package 10-lead plastic msop t jmax = 125c, ja = 120c/w, jc = 45c/w order part number ms8 part marking* order part number dd part marking* order part number ms part marking* ltc2857cms8-1 ltc2857ims8-1 ltc2857cms8-2 ltc2857ims8-2 ltcmc ltcmc ltcmk ltcmk LTC2858CDD-1 ltc2858idd-1 ltc2858cdd-2 ltc2858idd-2 lcgr lcgr lcmr lcmr ltc2858cms-1 ltc2858ims-1 ltc2858cms-2 ltc2858ims-2 ltcgq ltcgq ltcmq ltcmq order options tape and reel: add #tr lead free: add #pbf lead free tape and reel: add #trpbf lead free part marking: http://www.linear.com/leadfree/ 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. storage temperature range msop ................................................ C65c to 150c dfn .................................................... C65c to 125c lead temperature (soldering, 10 sec) msop ............................................................... 300c
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 3 285678fb electrical characteristics symbol parameter conditions min typ max units driver |v od | differential driver output voltage r = , i o = 0ma, v cc = 4.5v (figure 1) v cc v r = 27 (rs485), v cc = 4.5v (figure 1) 1.5 v cc v r = 50 (rs422), v cc = 4.5v (figure 1) 2 v cc v |v od | change in magnitude of driver differential output voltage for complementary output states r = 27 or r = 50 (figure 1) 0.2 v v oc driver common mode output voltage r = 27 or r = 50 (figure 1) 3 v |v oc | change in magnitude of driver common mode output voltage for complementary output states r = 27 or r = 50 (figure 1) 0.2 v i ozd driver three-state (high impedance) output current on y and z de = 0v, v o = C7v, 12v, ltc2858-1, ltc2858-2 10 a i osd maximum driver short-circuit current C7v (y or z) 12v (figure 2) 120 250 ma receiver i in receiver input current (a, b) de = 0v, v cc = 0v or 5v, v in = 12v (figure 3) 125 a de = 0v, v cc = 0v or 5v, v in = C7v (figure 3) C100 a r in receiver input resistance re = 5v or 0v, de = 0v, v in = C7v, C3v, 3v, 7v, 12v (figure 3) 96 125 k v th receiver differential input threshold voltage C7v v cm 12v 0.2 v v th receiver input hysteresis v cm = 0v 25 mv v oh receiver output high voltage i o = C4ma, v id = 200mv, v cc = 4.5v 2.4 v v ol receiver output low voltage i o = 4ma, v id = C200mv, v cc = 4.5v 0.4 v i ozr receiver three-state (high impedance) output current on ro re = 5v, 0v v o v cc , ltc2856-1, ltc2856-2, ltc2858-1, ltc2858-2 1 a logic v ih logic input high voltage de, di, re, v cc = 5.5v 2 v v il logic input low voltage de, di, re, v cc = 4.5v 0.8 v i inl logic input current de, di, re 0 10 a supplies i ccs supply current in shutdown mode de = 0v, re = v cc , ltc2856-1, ltc2856-2, ltc2858-1, ltc2858-2 0 5 a i ccr supply current in receive mode no load, de = 0v, re = 0v, ltc2856-1, ltc2856-2, ltc2858-1, ltc2858-2 540 900 a i cct supply current in transmit mode no load, de = v cc , re = v cc ltc2856-1 ltc2858-1 630 1000 a ltc2856-2 ltc2858-2 670 1100 a i cctr supply current with both driver and receiver enabled no load, de = v cc , re = 0v ltc2856-1 ltc2857-1 ltc2858-1 660 1100 a ltc2856-2 ltc2857-2 ltc2858-2 700 1200 a the denotes the speci?cations which apply over the full operating temperature range, otherwise speci?cations are at t a = 25c. v cc = 5v unless otherwise noted. (note 2)
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 4 285678fb switching characteristics the denotes the speci?cations which apply over the full operating temperature range, otherwise speci?cations are at t a = 25c. v cc = 5v unless otherwise noted. (note 2) symbol parameter conditions min typ max units driver in ltc2856-1, ltc2857-1, ltc2858-1 f max maximum data rate (note 3) 20 mbps t plhd , t phld driver input to output r diff = 54 , c l = 100pf (figure 4) 10 50 ns t pd driver input to output difference |t plhd C t phld | r diff = 54 , c l = 100pf (figure 4) 1 6 ns t skewd driver output y to output z r diff = 54 , c l = 100pf (figure 4) 1 6 ns t rd , t fd driver rise or fall time r diff = 54 , c l = 100pf (figure 4) 4 12.5 ns t zld , t zhd , t lzd , t hzd driver enable or disable time r l = 500 , c l = 50pf, re = 0v, ltc2856-1, ltc2858-1 (figure 5) 70 ns t zhsd , t zlsd driver enable from shutdown r l = 500 , c l = 50pf, re = v cc , ltc2856-1, ltc2858-1 (figure 5) 8 s t shdn time to shutdown (de = , re = v cc ) or (de = 0v, re = ), ltc2856-1, ltc2858-1 (figure 5) 100 ns driver in ltc2856-2, ltc2857-2, ltc2858-2 f maxs maximum data rate (note 3) 250 kbps t plhds , t phlds driver input to output r diff = 54 , c l = 100pf (figure 4) 0.95 1.5 s t pds driver input to output difference |t plhd C t phld | r diff = 54 , c l = 100pf (figure 4) 50 500 ns t skewds driver output a to output b r diff = 54 , c l = 100pf (figure 4) 200 500 ns t rds , t fds driver rise or fall time r diff = 54 , c l = 100pf (figure 4) 0.90 1.5 s t zhds , t zlds driver enable time r l = 500 , c l = 50pf, re = 0v, ltc2856-2, ltc2858-2 (figure 5) 300 ns t lzds , t hzds driver disable time r l = 500 , c l = 50pf, re = 0v, ltc2856-2, ltc2858-2 (figure 5) 70 ns t zhsds , t zlsds driver enable from shutdown r l = 500 , c l 50pf, re = v cc , ltc2856-2, ltc2858-2 (figure 5) 8 s t shdns time to shutdown (de = 0v, re ) or (de = , re = v cc ), ltc2856-2, ltc2858-2 (figure 5) 500 ns receiver t plhr , t phlr receiver input to output c l = 15pf, v cm = 1.5v, |v ab | = 1.5v, t r and t f < 4ns (figure 6) 50 70 ns t skewr differential receiver skew, |t plhr C t phlr | c l = 15pf (figure 6) 1 6 ns t rr , t fr receiver output rise or fall time c l = 15pf (figure 6) 3 12.5 ns t zlr , t zhr , t lzr , t hzr receiver enable/disable r l = 1k, c l = 15pf, de = v cc , ltc2856-1, ltc2856-2, ltc2858-1, ltc2858-2 (figure 7) 50 ns t zhsr , t zlsr receiver enable from shutdown r l = 1k, c l = 15pf, de = 0v, ltc2856-1, ltc2856-2, ltc2858-1, ltc2858-2 (figure 7) 8 s 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 of device pins are negative. all voltages are referenced to device ground unless otherwise speci?ed. note 3: maximum data rate is guaranteed by other measured parameters and is not tested directly. note 4: this ic includes overtemperature protection that is intended to protect the device during momentary overload conditions. junction temperature will exceed 125c when overtemperature protection is active. continuous operation above the speci?ed maximum operating junction temperature may result in device degradation or failure.
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 5 285678fb test circuits C + driver di gnd or v cc r 285678 f01 y z r v oc C + v od figure 1. driver dc characteristics figure 2. driver output short-circuit current driver di gnd or v cc 285678 f02 y z + C i osd C7v to +12v + C receiver 285678 f03 a or b v in i in b or a v in i in r in = figure 3. receiver input current and input resistance driver di r diff c l c l 285678 f04a y z t plhd , t plhds 1/2 v o 90% 90% 0 0 t rd , t rds t fd , t fds 10% 285678 f04b 10% v o v cc y, z di y- z 0v t skew d , t skewds t phld , t phlds figure 4. driver timing measurement figure 5. driver enable and disable timing measurement driver di v cc or gnd gnd or v cc v cc or gnd r l r l c l 285678 f05a y z de c l t zld , t zlds , t zlsd , t zlsds t zhd , t zhds , t zhsd , t zhsds t hzd , t hzds , t shdn , t shdns t lzd , t lzds 1/2 v cc 1/2 v cc 1/2 v cc de y or z z or y v cc v cc v ol v o v oh 0v 0v 0.5v 0.5v 285678 f05b
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 6 285678fb test circuits a b v cm v ab /2 v ab /2 ro c l 285678 f06a receiver t plhr t phlr 90% 0 t skewr = t plhr C t phlr 90% 1/2 v cc 1/2 v cc t rr t fr 10% 285678 f06b 10% v ab v cc v o 0 Cv ab ro a-b figure 6. receiver propagation delay measurements a b 0v or v cc v cc or 0v ro re c l di = 0v or v cc r l v cc or gnd 285678 f07a receiver t zlr , t zlsr t zhr , t zhsr t hzr t lzr 1/2 v cc 1/2 v cc 1/2 v cc re ro ro v cc v cc v ol v o v oh 0v 0v 0.5v 0.5v 285678 f05b figure 7. receiver enable/disable time measurements function tables ltc2856-1, ltc2856-2 logic inputs mode a, b ro de re 0 0 receive r in driven 0 1 shutdown r in high-z 1 0 transceive driven driven 1 1 transmit driven high-z ltc2858-1, ltc2858-2 logic inputs mode a, b y, z ro de re 0 0 receive r in high-z driven 0 1 shutdown r in high-z high-z 1 0 transceive r in driven driven 1 1 transmit r in driven high-z
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 7 285678fb typical performance characteristics receiver skew vs temperature driver skew vs temperature driver propagation delay vs temperature driver output short-circuit current vs temperature driver output low/high voltage vs output current driver differential output voltage vs temperature receiver output voltage vs output current (source and sink) receiver propagation delay vs temperature supply current vs data rate temperature ( c) C40 C1 receiver skew (ns) 0 1 2 C20 0 20 4 0 385678 g01 60 80 100 120 v ab = 1.5v c l = 15pf temperature ( c) C40 C1 driver skew (ns) 0 1 2 C20 0 20 4 0 385678 g02 60 80 100 120 r diff = 54 ? c l = 100pf temperature ( c) C40 driver prop delay (ns) 12 14 16 80 285678 g03 10 8 0 4 0 C20 100 20 60 120 6 4 18 r diff = 54 ? c l = 100pf temperature ( c) C40 80 output short-circuit current (ma) 100 120 140 160 C20 0 20 4 0 285678 g04 60 80 100 120 source (v out = 0v) sink (v out = 5v) output current (ma) 0 1 0 0 output voltage (v) 2 5 v oh v ol 20 40 50 285678 g05 1 4 3 30 60 70 temperature ( c) C40 output voltage (v) 3 4 5 20 60 120 285678 g0 6 2 1 0 C20 0 40 80 100 r diff = r diff = 100 ? r diff = 54 ? output current (ma) 0 output voltage (v) 3 4 5 4 285678 g07 2 1 0 1 2 3 sink source 5 temperature ( c) C40 prop delay (ns) 50 60 120 285678 g0 8 40 30 0 40 80 C20 20 60 100 70 45 55 35 65 v ab = 1.5v c l = 15pf data rate (mbps) 0.1 0 supply current (ma) 40 50 60 1 1 0 100 285678 g0 9 30 20 10 c l = 100pf r diff = r diff = 100 ? r diff = 54 ? t a = 25c, v cc = 5v unless otherwise noted.
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 8 285678fb pin functions pin name pin number description ltc2856-1 ltc2856-2 ltc2857-1 ltc2857-2 ltc2858-1 ltc2858-2 ro 1 2 1 receiver output. if the receiver output is enabled (re low) a nd a > b by 200mv, then ro will be high. if a < b by 200mv, then ro will be low. if the receiver inputs are open, shorted or terminated without a valid signal, ro will be high. re 2 2 receiver enable. a low enables the receiver. a high input forces the receiver output into a high impedance state. de 3 3 driver enable. a high on de enables the driver. a low input will force the driver outputs into a high impedance. if re is high with de low, the part will enter a low power shutdown state. di 4 3 4 driver input. if the driver outputs are enabled (de high), the n a low on di forces the driver positive output low and negative output high. a high on di, with the driver outputs enabled, forces the driver positive output high and negative output low. gnd 5/9* 4/9* 5/11* ground. *the exposed pad on the dfn packages should be connected to ground. y 5 6 noninverting driver output for the ltc2857-1, ltc2857-2, ltc2858-1 and ltc2858-2. high impedance when the driver is disabled (ltc2858-1) or unpowered. z 6 7 inverting driver output for the ltc2857-1, ltc2857-2, ltc2858-1 and ltc2858-2. high impedance when the driver is disabled (ltc2858-1) or unpowered. b 7 7 8 inverting receiver input (and inverting driver output for the ltc2856-1 and ltc2856-2). impedance is > 96k in receive mode or unpowered. a 6 8 9 noninverting receiver input (and noninverting driver output for the ltc2856-1 and ltc2856-2). impedance is > 96k in receive mode or unpowered. v cc 8 1 10 positive supply. 4.5v < v cc < 5.5v. bypass with a 0.1f ceramic capacitor.
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 9 285678fb block diagrams sleep/shutdown logic and dela y receiver driver ro re de di a (15kv) b (15kv) ltc2856-1, ltc2856-2 receiver driver ro di 2857 bd a (15kv) z (15kv) y (15kv) b (15kv) ltc2857-1, ltc2857-2 ltc2858-1, ltc2858-2 sleep/shutdown logic and dela y receiver driver ro re de di 2858 bd a (15kv) z (15kv) y (15kv) b (15kv)
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 10 285678fb applications information driver the driver provides full rs485 and rs422 compatibility. when enabled, if di is high, y-z is positive for the full-duplex devices and a-b is positive for the half-duplex device. when the driver is disabled, both outputs are high imped - ance. for the full-duplex devices, the leakage on the driver output pins is guaranteed to be less than 10a over the entire common mode range of C7v to 12v. on the half- duplex device, the impedance is dominated by the receiver input resistance, r in . driver overvoltage and overcurrent protection the driver outputs are protected from short circuits to any voltage within the absolute maximum range of (v cc C 15v) to 15v. the maximum current in this condition is 250ma. if the pin voltage exceeds about 10v, current limit folds back to about half of the peak value to reduce overall power dissipation and avoid damaging the part. all devices also feature thermal shutdown protection that disables the driver and receiver output in case of excessive power dissipation (see note 4). slew limiting for emi emissions control the ltc2856-2, ltc2857-2 and the ltc2858-2 feature reduced slew rate driver outputs to control the high fre - quency emi emissions from equipment and data cables. these devices are limited to data rates of 250kbaud or less. slew limiting also mitigates the adverse affects of imperfect transmission line termination caused by stubs or mismatched cable. figures 10 and 11 show the output waveforms from the ltc2858-1 and its slew rate limited counterpart, the ltc2858-2, operating at 250kbps. the corresponding frequency spectrums show signi?cant reduction in the high frequency harmonics for the slew rate limited device. receiver and failsafe with the receiver enabled, when the absolute value of the differential voltage between the a and b pins is greater than 200mv, the state of ro will re?ect the polarity of (a-b). these parts have a failsafe feature that guarantees the receiver output to be in a logic-high state when the inputs are either shorted, left open or terminated, but not driven for more than about 3s. the delay prevents signal zero crossings from being interpreted as shorted inputs and causing ro to go high inadvertently. this failsafe feature is guaranteed to work for inputs spanning the entire com - mon mode range of C7v to 12v. the receiver output is internally driven high (to v cc ) or low (to ground) with no external pull-up needed. when the receiver is disabled the ro pin becomes high-z with leakage of less than 1a for voltages within the supply range. receiver input resistance the receiver input resistance from a or b to ground is guaranteed to be greater than 96k. this is 8 higher than the requirements for rs485 standard and thus this receiver represents a one-eighth unit load. this, in turn, means that 8 the standard number of receivers, or 256 total, can be connected to a line without loading it beyond what is called out in the rs485 standard. the input resistance of the receivers is unaffected by enabling/disabling the receiver and by powering/unpowering the part. supply current the unloaded static supply currents in these devices are very lowtypically under 700a for all modes of opera - tion. in applications with resistively terminated cables, the supply current is dominated by the driver load. for example, when using two 120 terminators with a dif - ferential driver output voltage of 2v, the dc load current is 33ma, which is sourced by the positive voltage supply. power supply current increases with toggling data due to capacitive loading and this term can increase signi?cantly at high data rates. figure 8 shows supply current vs data rate for two different capacitive loads for the circuit con - ?guration of figure 4.
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 11 285678fb applications information high speed considerations a ground plane layout is recommended. a 0.1f bypass capacitor less than one-quarter inch away from the v cc pin is also recommended. the pc board traces connected to signals a/b and z/y should be symmetrical and as short as possible to maintain good differential signal integrity. to minimize capacitive effects, the differential signals should be separated by more than the width of a trace and should not be routed on top of each other if they are on different signal planes. care should be taken to route outputs away from any sensitive inputs to reduce feedback effects that might cause noise, jitter or even oscillations. for example, in the full-duplex ltc2857-1, di and a/b should not be routed near the driver or receiver outputs. the logic inputs have 100mv of hysteresis to provide noise immunity. fast edges on the outputs can cause glitches in the ground and power supplies which are exacerbated by capacitive loading. if a logic input is held near its threshold (typically 1.5v), a noise glitch from a driver transition may exceed the hysteresis levels on the logic and data input pins causing an unintended state change. this can be avoided by maintaining normal logic levels on the pins and by slewing inputs through their thresholds by faster than 1v/s when transitioning. good supply decoupling and proper line termination also reduce glitches caused by driver transitions. cable length vs data rate for a given data rate, the maximum transmission distance is bounded by the cable properties. a typical curve of cable length vs data rate compliant with the rs485 standard is shown in figure 9. three regions of this curve re?ect differ - ent performance limiting factors in data transmission. in the ?at region of the curve, maximum distance is determined by resistive losses in the cable. the downward sloping region represents limits in distance and data rate due to ac losses in the cable. the solid vertical line represents the speci?ed maximum data rate in the rs485 standard. the dashed line at 250kbps shows the maximum data rate of the low-emi ltc2856-2, ltc2857-2, and ltc2858-2. the dashed line at 20mbps shows the maximum data rates of the ltc2856-1, ltc2857-1 and ltc2858-1. figure 8. supply current vs data rate cable termination proper cable termination is very important for good signal ?delity. if the cable is not terminated with its char - acteristic impedance, re?ections will result in distorted waveforms. rs485 transceivers typically communicate over twisted- pair cables with characteristic impedance ranging from 100 to 120 . each end of the network should be termi - nated with a discrete resistor matching the characteristic impedance or with an ltc2859/ltc2861 transceiver with integrated termination capability. figure 9. cable length vs data rate (rs485 standard shown in solid vertical lines) data rate (kbps) 10 2 45 current (ma) 65 70 75 10 3 10 4 10 5 285678 f08 60 55 50 r diff = 54 ? c l = 1000pf c l = 100pf 285678 f09 data rate (bps) cable length (ft) 10k 1m 10m 100k 100m 100 1k 10 10k low-emi mode max data rate rs485 max data rate normal mode max data rate
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 12 285678fb applications information time-based traces frequency spectrum figure 10. ltc2858-1 driver output at 100khz into 100 resistor time-based traces frequency spectrum figure 11. ltc2858-2 driver output at 100khz into 100 resistor failsafe 0 application (idle state = logic 0) typical applications d v cc i 1 i 2 100k b a a b ro di ltc2856-1 285678 ta02 r 2 s/div y, z 1v/div y-z 2v/div 285678 f10a 1.25mhz/div y-z 10db/div 285678 f10b 2 s/div y-z 2v/div y, z 1v/div 285678 f11a 1.2mhz/div y-z 10db/div 285678 f11b
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 13 285678fb package description dd package 8-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1698) 3.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (weed-1) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on top and bottom of package 0.38 0.10 bottom viewexposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.115 typ 2.38 0.10 (2 sides) 1 4 8 5 pin 1 top mark (note 6) 0.200 ref 0.00 C 0.05 (dd8) dfn 1203 0.25 0.05 2.38 0.05 (2 sides) recommended solder pad pitch and dimensions 1.65 0.05 (2 sides) 2.15 0.05 0.50 bsc 0.675 0.05 3.5 0.05 package outline 0.25 0.05 0.50 bsc dd package 10-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1699) 3.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (weed-2). check the ltc website data sheet for current status of variation assignment 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.38 0.10 bottom viewexposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.115 typ 2.38 0.10 (2 sides) 1 5 10 6 pin 1 top mark (see note 6) 0.200 ref 0.00 C 0.05 (dd10) dfn 1103 0.25 0.05 2.38 0.05 (2 sides) recommended solder pad pitch and dimensions 1.65 0.05 (2 sides) 2.15 0.05 0.50 bsc 0.675 0.05 3.50 0.05 package outline 0.25 0.05 0.50 bsc
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 14 285678fb ms8 package 8-lead plastic msop (reference ltc dwg # 05-08-1660) package description msop (ms8) 0204 0.53 0.152 (.021 .006) seating plane note: 1. dimensions in millimeter/(inch) 2. drawing not to scale 3. dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.152mm (.006") per side 4. dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.152mm (.006") per side 5. lead coplanarity (bottom of leads after forming) shall be 0.102mm (.004") max 0.18 (.007) 0.254 (.010) 1.10 (.043) max 0.22 C 0.38 (.009 C .015) typ 0.127 0.076 (.005 .003) 0.86 (.034) ref 0.65 (.0256) bsc 0 C 6 typ detail a detail a gauge plane 1 2 3 4 4.90 0.152 (.193 .006) 8 7 6 5 3.00 0.102 (.118 .004) (note 3) 3.00 0.102 (.118 .004) (note 4) 0.52 (.0205) ref 5.23 (.206) min 3.20 C 3.45 (.126 C .136) 0.889 0.127 (.035 .005) recommended solder p ad la yout 0.42 0.038 (.0165 .0015) typ 0.65 (.0256) bsc
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 15 285678fb 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 ms package 10-lead plastic msop (reference ltc dwg # 05-08-1661) msop (ms) 0603 0.53 0.152 (.021 .006) seating plane 0.18 (.007) 1.10 (.043) max 0.17 C 0.27 (.007 C .011) typ 0.127 0.076 (.005 .003) 0.86 (.034) ref 0.50 (.0197) bsc 1 2 3 4 5 4.90 0.152 (.193 .006) 0.497 0.076 (.0196 .003) ref 8 9 10 7 6 3.00 0.102 (.118 .004) (note 3) 3.00 0.102 (.118 .004) (note 4) note: 1. dimensions in millimeter/(inch) 2. drawing not to scale 3. dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.152mm (.006") per side 4. dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.152mm (.006") per side 5. lead coplanarity (bottom of leads after forming) shall be 0.102mm (.004") max 0.254 (.010) 0 C 6 typ detail a detail a gauge plane 5.23 (.206) min 3.20 C 3.45 (.126 C .136) 0.889 0.127 (.035 .005) recommended solder p ad la yout 0.305 0.038 (.0120 .0015) typ 0.50 (.0197) bsc
ltc2856-1/ltc2856-2 ltc2857-1/ltc2857-2 ltc2858-1/ltc2858-2 16 285678fb linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2006 lt 1206 ? rev b ? printed in usa related parts part number description comments ltc485 low power rs485 interface transceiver i cc = 300a (typ) ltc491 differential rs485 driver and receiver pair i cc = 300a ltc1480 3.3v ultralow power rs485 transceiver 3.3v operation ltc1483 ultralow power rs485 low emi transceiver controlled driver slew rate ltc1485 differential bus transceiver 10mbaud operation ltc1487 ultralow power rs485 with low emi, shutdown and high input impedance up to 256 transceiver on the bus ltc1520 50mbps precision quad line receiver channel-to-channel skew 400ps (typ) ltc1535 isolated rs485 full-duplex transceiver 2500v rms isolation in surface mount package ltc1685 52mbps rs485 transceiver with precision delay propagation delay skew 500ps (typ) lt1785 60v fault protected rs485 transceiver 60v tolerant, 15kv esd ltc2859/ ltc2861 20mbps rs485 transceivers with integrated switchable termination integrated, switchable, 120 termination resistor, 15kv esd multi-node network and end termination using the ltc2856-1 r d ltc2856-1 r d ltc2856-1 d te = 5v r d te = 5v 285678 ta03 r ltc2859 ltc2859 typical application

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