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ltc2854/ltc2855 1 285455fb features description applications typical application product selection guide 3.3v 20mbps rs485/rs422 transceivers with integrated switchable termination the ltc ? 2854 and ltc2855 are low power, 20mbps rs485/rs422 transceivers operating on 3.3v supplies. the receiver includes a logic-selectable 120 termina- tion, one-eighth unit load supporting up to 256 nodes per bus (c, i-grade), 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 a thermal shutdown. enhanced esd protection allows the ltc2854 to withstand 25kv (human body model) and the ltc2855 to withstand 15kv on the transceiver interface pins without latchup or damage. low power rs485/rs422 transceiver level translator backplane transceiver integrated, logic-selectable 120 termination resistor 3.3v supply voltage 20mbps maximum data rate no damage or latchup up to 25kv hbm high input impedance supports 256 nodes (c, i-grade) operation up to 125c (h-grade) guaranteed failsafe receiver operation over the entire common mode range current limited drivers and thermal shutdown delayed micropower shutdown: 5a maximum (c, i-grade) power up/down glitch-free driver outputs low operating current: 370a typical in receive mode compatible with tia/eia-485-a speci? cations available in 10-pin 3mm 3mm dfn, 12-pin 4mm 3mm dfn and 16-pin ssop packages ltc2854 at 20mbps into 54 part number duplex package ltc2854 half dfn-10 ltc2855 full ssop-16, dfn-12 re te ro de di r d 285455 ta01 ltc2854 120 re ro te de di r d ltc2854 120 re ro te de di r d ltc2854 120 , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. 20ns/div 2v/div 285455 ta01b a-b b a di
ltc2854/ltc2855 2 285455fb absolute maximum ratings supply voltage (v cc ) ................................... ?0.3v to 7v logic input voltages ( re, de, di, te) ............ ?0.3v to 7v interface i/o: a, b, y, z ...................................... (v cc ?15v) to +15v (a-b) or (b-a) with terminator enabled ..................6v receiver output voltage (ro) ........ ?0.3v to (v cc +0.3v) (note 1) operating temperature (note 4) ltc2854c, ltc2855c .............................. 0c to 70c ltc2854i, ltc2855i ............................. ?40c to 85c ltc2854h, ltc2855h ........................ ?40c to 125c storage temperature range ................... ?65c to 150c lead temperature (soldering, 10 sec) gn package ...................................................... 300c top view dd package 10-lead ( 3mm 3mm ) plastic dfn 10 9 6 7 8 4 5 3 2 1 v cc b a nc gnd ro re de di te 11 exposed pad (pin 11) pcb gnd connection t jmax = 150c,
ltc2854/ltc2855 3 285455fb the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c, v cc = 3.3v unless otherwise noted (note 2). symbol parameter conditions min typ max units driver |v od | differential driver output voltage r = , v cc = 3v (figure 1) r = 27, v cc = 3v (figure 1) r = 50, v cc = 3.13v (figure 1) 1.5 2 v cc v cc v cc v v v 6 |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) 3v 6 |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 = ov, (y or z) = C7v, 12v (ltc2855) 10 a i osd maximum driver short-circuit current C7v (y or z) 12v (figure 2) C250 180 250 300 ma ma receiver i in receiver input current (a, b) de = te = 0v, v cc = 0v or 3.3v, v in = 12v (figure 3) (c, i-grade) de = te = 0v, v cc = 0v or 3.3v, v in = C7v, (figure 3) (c, i-grade) C100 125 a a de = te = 0v, v cc = 0v or 3.3v, v in = 12v (figure 3) (h-grade) de = te = 0v, v cc = 0v or 3.3v, v in = C7v, (figure 3) (h-grade) C145 250 a a r in receiver input resistance re = v cc or 0v, de = te = 0v, v in = C7v, C3v, 3v, 7v, 12v (figure 3) (c, i-grade) 96 125 k re = v cc or 0v, de = te = 0v, v in = C7v, C3v, 3v, 7v, 12v (figure 3) (h-grade) 48 125 k v th receiver differential input threshold voltage C7v b 12v 0.2 v 6 v th receiver input hysteresis b = 0v 25 mv v oh receiver output high voltage i(ro) = C4ma, a-b = 200mv, v cc = 3v 2.4 v v ol receiver output low voltage i(ro) = 4ma, a-b = C200mv, v cc = 3v 0.4 v i ozr receiver three-state (high impedance) output current on ro re = v cc , 0v ro v cc 1 a i osr receiver short-circuit current 0v ro v cc 85 ma r term receiver input terminating resistor te = v cc , v ab = 2v, v b = C7v, 0v, 10v (figure 8) 108 120 156 logic v ih logic input high voltage v cc = 3.6v 2v v il logic input low voltage v cc = 3v 0.8 v i inl logic input current 0 10 a supplies i ccs supply current in shutdown mode de = 0v, re = v cc , te = 0v (c, i-grade) (h-grade) 0 0 5 15 a a i ccr supply current in receive mode de = 0v, re = 0v, te = 0v 370 900 a electrical characteristics
ltc2854/ltc2855 4 285455fb symbol parameter conditions min typ max units driver 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 6 t pd driver input to output difference |t plhd -t phld | r diff = 54, c l = 100pf (figure 4) 16 ns t skewd driver output y to output z r diff = 54, c l = 100pf (figure 4) 16 ns t rd , t fd driver rise or fall time r diff = 54, c l = 100pf (figure 4) 412.5 ns t zld , t zhd , t lzd , t hzd driver enable or disable time r l = 500, c l = 50pf, re = 0 (figure 5) 70 ns t zhsd , t zlsd driver enable from shutdown r l = 500, c l = 50pf, re = v cc (figure 5) 8s t shdn time to shutdown r l = 500, c l = 50pf (de = , re = v cc ) or (de = 0, re b ) (figure 5) 100 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 -t phlr | c l = 15pf (figure 6) 16 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 (figure 7) 50 ns t zhsr , t zlsr receiver enable from shutdown r l = 1k, c l = 15pf, de = 0v (figure 7) 8s t rten , t rtz termination enable or disable time v b = 0v, v ab = 2v, re = v cc , de = 0v (figure 8) 100 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. high temperatures degrade operating lifetimes. operating lifetime is derated at temperatures greater than 105c 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. symbol parameter conditions min typ max units i cct supply current in transmit mode no load, de = v cc , re = v cc , te = 0v 450 1000 a i cctr supply current with both driver and receiver enabled no load, de = v cc , re = 0v, te = 0v 450 1000 a i ccterm supply current in termination mode de = 0v, re = v cc , te = v cc 110 180 a i cctermr supply current in receive and termination mode de = 0v, re = 0v, te = v cc 450 950 a i cctermt supply current in transmit and termination mode de = v cc , re = v cc , te = v cc 470 1000 a i cctermtr supply current with driver, receiver and termination enabled de = v cc , re = 0v, te = v cc 470 1000 a esd protection esd protection for rs485/rs422 pins a, b on ltc2854, human body model y, z, a, b on ltc2855, human body model 25 15 kv kv the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c, v cc = 3.3v, t e = 0v unless otherwise noted (note 2). 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. overtemperature protection activates at a junction temperature exceeding 150c. continuous operation above the speci? ed maximum operating junction temperature may result in device degradation or failure. the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c, v cc = 3.3v, t e = 0v unless otherwise noted (note 2). electrical characteristics switching characteristics
ltc2854/ltc2855 5 285455fb figure 1. driver dc characteristics figure 2. driver output short-circuit current figure 4. driver timing measurement figure 3. receiver input current and input resistance gnd or v cc + v oc C r r z y gnd or v cc di driver + v od C C7v to +12v z y di driver i osd + C 285455 f01-2 + C receiver 285455 f03 a or b v in i in b or a v in i in r in = driver di r diff c l c l 285455 f04a y z t plhd 1/2 v o 90% 90% 00 t rd t fd 10% 285455 f04b 10% v o v cc y, z di y-z 0v t skewd t phld figure 5. driver enable and disable timing measurements driver di v cc or gnd gnd or v cc v cc or gnd r l r l c l 285455 f05a y z de c l t zld , t zlsd t zhd , t zhsd t hzd , t shdn t lzd 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 285455 f05b test circuits
ltc2854/ltc2855 6 285455fb figure 6. receiver propagation delay measurements figure 7. receiver enable and disable timing measurements a b v cm v ab /2 v ab /2 ro c l 285455 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 t r t f 10% 90% 10% 90% 10% 285455 f06b 10% v ab v cc v o 0 Cv ab ro a-b a b 0v or v cc v cc or 0v di = 0v or v cc ro re c l r l v cc or gnd 285455 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 285455 f07b t rten t rtz v cc b a i a te 285455 f08 receiver 90% 10% 0v te + C + C v ab v b r term = i a i a v ab 1/2 v cc ro figure 8. termination resistance and timing measurements test circuits
ltc2854/ltc2855 7 285455fb typical performance characteristics receiver skew vs temperature driver skew vs temperature driver propagation delay vs temperature r term vs temperature driver output low/high voltage vs output current driver differential output voltage vs temperature receiver propagation delay vs temperature supply current vs data rate t a = 25c, v cc = 3.3v, unless otherwise noted. receiver output voltage vs output current (source and sink) temperature (?c) C40 receiver skew (ns) 1 80 285455 g01 0 2 040 C20 100 20 60 120 C1 v ab = 1.5v c l = 15pf temperature (?c) C40 driver skew (ns) 1 80 285455 g02 0 040 C20 100 20 60 120 C1 r diff = 54 c l = 100pf temperature (?c) C40 prop delay (ns) 12 14 16 80 285455 g03 10 9 040 C20 100 20 60 120 6 4 18 r diff = 54 c l = 100pf temperature (?c) C40 resistance () 120 125 130 80 285455 g04 115 110 040 C20 100 20 60 120 105 100 135 output current (ma) 0 output voltage (v) 2 3 60 285455 g05 1 20 40 10 30 50 70 0 v oh v ol temperature (?c) C40 output voltage (v) 2 3 80 285455 g06 1 040 C20 100 20 60 120 0 r diff = r diff = 100 r diff = 54 output current (ma) 0 output voltage (v) 2 3 285455 g07 1 24 1 356 0 source sink temperature (?c) C40 prop delay (ns) 55 60 65 80 285455 g08 50 45 040 C20 100 20 60 120 40 35 70 v ab = 1.5v c l = 15pf data rate (mbps) 0.1 0 supply current (ma) 40 50 60 1 10 100 285455 g09 30 20 10 c l = 100pf r diff = r diff = 100 r diff = 54
ltc2854/ltc2855 8 285455fb ro (pin 1): receiver output. if the receiver output is enabled ( re low) and 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 signal, ro will be high. re (pin 2): receiver enable. a low enables the receiver. a high input forces the receiver output into a high imped- ance state. de (pin 3): driver enable. a high on de enables the driver. a low input will force the driver outputs into a high imped- ance. if re is high with de and te low, the part will enter a low power shutdown state. di (pin 4): driver input. if the driver outputs are enabled (de high), then a low on di forces the driver positive out- put low and negative output high. a high on di, with the driver outputs enabled, forces the driver positive output high and negative output low. (dd/de/gn) te (pin 5): internal termination resistance enable. a high input will connect a termination resistor (120 typical) between pins a and b. gnd (pins 6,11/6,13/6): ground. pins 11 and 13 are backside thermal pad, connected to ground. y (pins na/8/12): positive driver output for ltc2855. z (pins na/9/13): negative driver output for ltc2855. b (pins 9/10/14): negative receiver input (and negative driver output for ltc2854). a (pins 8/11/15): positive receiver input (and positive driver output for ltc2854). v cc (pins 10/12/16): positive supply. v cc = 3.0v < v cc < 3.6v. bypass with 0.1f ceramic capacitor. pin functions
ltc2854/ltc2855 9 285455fb block diagrams ltc2854 logic inputs de re te mode a, b ro terminator 0 0 0 receive r in driven off 0 0 1 receive with term r term driven on 0 1 0 shutdown r in high-z off 0 1 1 term only r term high-z on 1 0 0 transmit with receive driven driven off 1 0 1 transmit with receive and term driven driven on 1 1 0 transmit driven high-z off 1 1 1 transmit with term driven high-z on ltc2855 logic inputs de re te mode a, b y, z ro terminator 0 0 0 receive r in high-z driven off 0 0 1 receive with term r term high-z driven on 0 1 0 shutdown r in high-z high-z off 0 1 1 term only r term high-z high-z on 1 0 0 transmit with receive r in driven driven off 1 0 1 transmit with receive and term r term driven driven on 1 1 0 transmit r in driven high-z off 1 1 1 transmit with term r term driven high-z on ltc2854 ltc2855 de ro di a (15kv) te v cc b (15kv) z (15kv) y (15kv) sleep/shutdown logic and delay receiver driver re 120 r term 120 r term de ro di a 25kv te b 25kv sleep/shutdown logic and delay receiver driver re 285455 bd v cc gnd 125k r in 125k r in 125k r in 125k r in gnd function tables
ltc2854/ltc2855 10 285455fb driver the driver provides full rs485/rs422 compatibility. when enabled, if di is high, y-z is positive for the full-duplex device (ltc2855) and a-b is positive for the half-duplex device (ltc2854). when the driver is disabled, both outputs are high- impedance. for the full-duplex ltc2855, 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 ltc2854, 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 C15v) to +15v. the typical peak current in this condition does not exceed 180ma. if a high driver output is shorted to a voltage just above v cc , a reverse current will ? ow into the supply. when this voltage exceeds v cc by about 1.4v, the reverse current turns off. preventing the driver from turning off with outputs shorted to output voltages just above v cc keeps the driver active even for receiver loads that have a positive common mode with respect to the driver a valid condition. the worst-case peak reverse short-circuit current can be as high as 300ma in extreme cold conditions. if this current cannot be absorbed by the supply, a 3.6v zener diode can be added in parallel with the supply to sink this current. all devices also feature thermal shutdown protection that disables the driver and receiver in case of excessive power dissipation (see note 4). 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). the ltc2854/ltc2855 have a failsafe feature that guaran- tees the receiver output to be in a logic-high state when the inputs are either shorted, left open, or terminated (externally or internally), but not driven. this failsafe fea- ture is guaranteed to work for inputs spanning the entire common 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 guar- anteed to be greater than 96k (c, i-grade) when the termi- nation is disabled. this is 8x higher than the requirements for the rs485 standard and thus this receiver represents a one-eighth unit load. this, in turn, means that 8x the standard number of receivers, or 256 total, can be con- nected to a line without loading it beyond what is called out in the rs485 standard. the receiver input resistance from a or b to ground on high temperature h-grade parts is greater than 48k providing a one-quarter unit load. the input resistance of the receivers is unaffected by enabling/ disabling the receiver and by powering/unpowering the part. the equivalent input resistance looking into a and b is shown in figure 9. the termination resistor cannot be enabled by te if the device is unpowered or in thermal shutdown mode. 60 60 a te b 285455 f09 >96k >96k figure 9. equivalent input resistance into a and b (on the ltc2854, valid if driver is disabled) applications information
ltc2854/ltc2855 11 285455fb switchable 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. the ltc2854/ltc2855 are the ? rst 3.3v rs485/rs422 transceivers to offer integrated switchable termination resistors on the receiver input pins. this provides the advantage of being able to easily change, through logic control, the line termination for optimal performance when con? guring transceiver networks. when the te pin is high, the termination resistor is enabled and the differential resistance from a to b is 120. figure 10 shows the i/v characteristics between pins a and b with the termination resistor enabled and disabled. the resistance is maintained over the entire rs485 common mode range of C7v to +12v as shown in figure 11. the integrated termination resistor has a high frequency response which does not limit performance at the maximum speci? ed data rate. figure 12 shows the magnitude and phase of the termination impedance vs frequency. figure 10. curve trace between a and b with termination enabled and disabled figure 11. typical resistance of the enabled terminator vs voltage on b pin figure 12. termination magnitude and phase vs frequency 10 C1 10 0 frequency (mhz) magnitude () phase () 10 1 80 95 110 125 140 155 170 185 C75 C60 C45 C30 C15 0 15 30 285455 f12 magnitude phase common mode voltage (v) C10 resistance () 130 140 150 10 285455 f11 120 110 100 C5 0 5 15 v ab = 2v applications information
ltc2854/ltc2855 12 285455fb 285455 f14 data rate (bps) cable length (ft) 10k 1m 10m 100k 100m 100 1k 10 10k rs485/rs422 max data rate ltc2854/ltc2855 max data rate supply current the unloaded static supply currents in the ltc2854/ ltc2855 are very low typically under 500a for all modes of operation. in applications with resistively ter- minated cables, the supply current is dominated by the driver load. for example, when using two 120 termina- tors with a differential driver output voltage of 2v, the dc current is 33ma, which is sourced by the positive voltage supply. this is true whether the terminators are external or internal such as in the ltc2854/ltc2855. power sup- ply current increases with toggling rate due to capacitive loading and this term can increase signi? cantly at high data rates. figure 13 shows supply current vs data rate for two different capacitive loads for the circuit con? guration of figure 4. high speed considerations a ground plane layout is recommended for the ltc2854/ ltc2855. 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 (ltc2855) 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 ltc2855, di and a/b should not be routed near the driver or receiver outputs. the logic inputs of the ltc2854/ltc2855 have 150mv 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 reduces 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/rs422 standards is shown in figure 14. three regions of this curve re? ect different 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/rs422 standards. the dashed lines at 20mbps show the maximum data rates of the ltc2854/ltc2855. figure 14. cable length vs data rate (rs485/ rs422 standards shown in vertical solid line) figure 13. supply current vs data rate data rate (mbps) 0.1 20 supply current (ma) 60 70 80 1 10 100 285455 f13 50 40 30 r diff = 54 c l = 1000pf c l = 100pf applications information
ltc2854/ltc2855 13 285455fb 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 0.3 8 0.10 bottom view?xposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.115 typ 2.3 8 0.10 (2 sides) 1 5 10 6 pin 1 top mark (see note 6) 0.200 ref 0.00 ?0.05 (dd) dfn 1103 0.25 0.05 2.3 8 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 dd package 10-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1699) failsafe 0 application (idle state = logic 0) 285455 ta03 "a" "b" a b r d ltc2854 i1 ro i2 di 100k v cc typical application package description
ltc2854/ltc2855 14 285455fb 4.00 0.10 (2 sides) 3.00 0.10 (2 sides) note: 1. drawing proposed to be a variation of version (wged) in jedec package outline m0-229 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 0.40 0.10 bottom view?xposed pad 1.70 0.10 0.75 0.05 r = 0.115 typ r = 0.05 typ 2.50 ref 1 6 12 7 pin 1 notch r = 0.20 or 0.35 45 chamfer pin 1 top mark (note 6) 0.200 ref 0.00 ?0.05 (ue12/de12) dfn 0 8 06 rev d 2.50 ref recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 2.20 0.05 0.70 0.05 3.60 0.05 package outline 3.30 0.10 0.25 0.05 0.50 bsc 1.70 0.05 3.30 0.05 0.50 bsc 0.25 0.05 de/ue package 12-lead plastic dfn (4mm 3mm) (reference ltc dwg # 05-08-1695 rev d) package description
ltc2854/ltc2855 15 285455fb gn16 (ssop) 0204 12 3 4 5 6 7 8 .229 ?.244 (5. 8 17 ?6.19 8 ) .150 ?.157** (3. 8 10 ?3.9 88 ) 16 15 14 13 .1 8 9 ?.196* (4. 8 01 ?4.97 8 ) 12 11 10 9 .016 ?.050 (0.406 ?1.270) .015 .004 (0.3 8 0.10) 45 0 ? 8 typ .007 ?.009 8 (0.17 8 ?0.249) .0532 ?.06 88 (1.35 ?1.75) .00 8 ?.012 (0.203 ?0.305) typ .004 ?.009 8 (0.102 ?0.249) .0250 (0.635) bsc .009 (0.229) ref .254 min recommended solder pad layout .150 ?.165 .0250 bsc .0165 .0015 .045 .005 inches (millimeters) note: 1. controlling dimension: inches 2. dimensions are in 3. drawing not to scale *dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side **dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side gn package 16-lead plastic ssop (narrow .150 inch) (reference ltc dwg # 05-08-1641) 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
ltc2854/ltc2855 16 285455fb linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (40 8 ) 432-1900 fax: (40 8 ) 434-0507 www.linear.com ? linear technology corporation 2007 lt 0308 rev b ? printed in usa typical application related parts part number description comments ltc485 low power rs485 interface transceiver i cc = 300a (typ) ltc491 differential 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 10mbps operation ltc1487 ultralow power rs485 with low emi, shutdown and high input impedance up to 256 transceivers 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 ltc2856/ltc2857/ ltc2858 20mbps and slew rate-limited, 15kv rs485/rs422 transceiver up to 256 transceivers on the bus ltc2859/ltc2861 20mbps rs485 transceiver with integrated switchable termination 5v integrated, switchable, 120 termination resistor, 15kv esd te = 3.3v te = 3.3v te = 0v r d te = 0v r d 285455 ta04 r d ltc2854 r d ltc2854 ltc2854 ltc2854 multi-node network with end termination using the ltc2854

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