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electrical specifications subject to change LTM2882 1 2882p typical application description dual isolated rs232 module transceiver + power the ltm ? 2882 is a complete galvanically isolated dual rs232 module ? transceiver. no external components are required. a single 3.3v or 5v supply powers both sides of the interface through an integrated, isolated dc/dc converter. a logic supply pin allows easy interfacing with different logic levels from 1.62v to 5.5v, independent of the main supply. coupled inductors and an isolation power transformer provide 2500v rms of isolation between the line transceiver and the logic interface. this device is ideal for systems with different grounds, allowing for large common mode voltages. uninterrupted communication is guaranteed for common mode transients greater than 30kv/s. this part is compatible with the tia/eia-232-f standard. driver outputs are protected from overload and can be shorted to ground or up to 15v without damage. an auxiliary isolated digital channel is available. this channel allows con? guration for half-duplex operation by control- ling the de pin. enhanced esd protection allows this part to withstand up to 10kv (human body model) on the transceiver interface pins to isolated supplies and across the isolation barrier to logic supplies without latchup or damage. l , lt, ltc, ltm, linear technology, the linear logo and module are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. isolated dual rs232 module transceiver features applications n isolator module technology n isolated dual rs232 transceiver: 2500v rms n integrated isolated dc/dc converter: 1w, 65% ef? ciency n no external components required n 1.62v to 5.5v logic supply for flexible digital interface n high speed operation 1mbps for 250pf/3k load 250kbps for 1nf/3k load 100kbps for 2.5nf/3k tia/eia-232-f load n 3.3v (LTM2882-3) or 5v (LTM2882-5) operation n no damage or latchup to 10kv esd hbm on isolated rs232 interface or across isolation barrier n high common mode transient immunity: 30kv/s n common mode working voltage: 560v peak n true rs232 compliant output levels n small low pro? le (15mm 11.25mm 2.8mm) surface mount lga package n isolated rs232 interface n industrial communication n test and measurement equipment n breaking rs232 ground loops 1mbps operation 2882 ta01a on din t1in r1out t2in r2out dout t1out r1in t2out r2in LTM2882 3.3v (LTM2882-3) 5v (LTM2882-5) v l v cc gnd gnd2 isolation barrier on off v cc2 de 5v available current: 150ma (LTM2882-5) 100ma (LTM2882-3) 400ns/div driver outputs tied to receiver inputs tout load = 250pf + rin rout load = 150pf 10v/div 5v/div tin t1out/r1in t2out/r2in 5v/div 2882 ta01b r1out r2out
LTM2882 2 2882p pin configuration absolute maximum ratings v cc to gnd .................................................. C0.3v to 6v v l to gnd .................................................... C0.3v to 6v v cc2 to gnd2 ............................................... C0.3v to 6v logic inputs t1in, t2in, on, din to gnd .......C0.3v to (v l + 0.3v) de to gnd2 ............................C0.3v to (v cc2 + 0.3v) logic outputs r1out, r2out to gnd ...............C0.3v to (v l + 0.3v) dout to gnd2 ........................C0.3v to (v cc2 + 0.3v) driver output voltage t1out, t2out to gnd2 ...........................C15v to 15v receiver input voltage r1in, r2in to gnd2 ............................... C25v to 25v operating temperature range (note 4) LTM2882c .........................................0c t a 70c LTM2882i ..................................... C40c t a 85c storage temperature range .................. C55c to 125c peak re? ow temperature (soldering, 10 sec) ....... 245c (note 1) v cc gnd gnd2 a b c d e f g h i j k l 12345678 lga package 32-pin (15mm s 11.25mm s 2.8mm) top view v cc2 v l on din t1in r1out t2in de dout t1out r1in t2out r2in r2out t jmax = 125c, ja = 29c/w, jc(top) = 27.9c/w, jc(bot) = 18c/w, jboard = 22.7c/w, weight = 1.1g lead free finish tray part marking* package description temperature range LTM2882cv-3#pbf LTM2882cv-3#pbf LTM2882v-3 32-pin (15mm 11.25mm 2.8mm) lga 0c to 70c LTM2882iv-3#pbf LTM2882iv-3#pbf LTM2882v-3 32-pin (15mm 11.25mm 2.8mm) lga C40c to 85c LTM2882cv-5#pbf LTM2882cv-5#pbf LTM2882v-5 32-pin (15mm 11.25mm 2.8mm) lga 0c to 70c LTM2882iv-5#pbf LTM2882iv-5#pbf LTM2882v-5 32-pin (15mm 11.25mm 2.8mm) lga C40c to 85c 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. consult ltc marketing for information on lead based ? nish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ this product is only offered in trays. for more information go to: http://www.linear.com/packaging/ order information
LTM2882 3 2882p electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. LTM2882-3 v cc = 3.3v, LTM2882-5 v cc = 5.0v, v l = v cc , and gnd = gnd2 = 0v, on = v l unless otherwise noted. symbol parameter conditions min typ max units supplies v cc input supply range LTM2882-3 l 3.0 3.3 3.6 v LTM2882-5 l 4.5 5.0 5.5 v v l logic supply range l 1.62 5.5 v i cc input supply current on = 0v l 010 a LTM2882-3, no load l 24 30 ma LTM2882-5, no load l 17 21 ma v cc2 regulated output voltage, loaded LTM2882-3 de = 0v, i load = 100ma l 4.7 5.0 v LTM2882-5 de = 0v, i load = 150ma l 4.7 5.0 v v cc2(noload) regulated output voltage, no load de = 0, no load 4.8 5.0 5.35 v ef? ciency i cc2 = 100ma, LTM2882-5 (note 2) 65 % i cc2 output supply short-circuit current l 250 ma driver v old driver output voltage low r l = 3k l C5 C5.7 v v ohd driver output voltage high r l = 3k l 5 6.2 v i osd driver short-circuit current v t1out , v t2out = 0v, v cc2 = 5.5v l 35 70 ma i ozd driver three-state (high impedance) output current de = 0v, v t1out , v t2out = 15v l 0.1 10 a receiver v ir receiver input threshold input low l 0.8 1.3 v input high l 1.7 2.5 v v hysr receiver input hysteresis l 0.1 0.4 1.0 v r in receiver input resistance C15v (v r1in , v r2in ) 15v l 357 k logic v ith logic input threshold voltage on, t1in, t2in, din = 1.62v v l < 2.35v l 0.25?v l 0.75?v l v on, t1in, t2in, din = 2.35v v l 5.5v l 0.4 0.67?v l v de l 0.4 0.67?v cc2 v i inl logic input current l 1 a v hys logic input hysteresis t1in, t2in, din (note 2) 150 mv v oh logic output high voltage r1out, r2out i load = C1ma (sourcing), 1.62v v l < 3.0v i load = C4ma (sourcing), 3.0v v l 5.5v l l v l C 0.4 v l C 0.4 v v dout, i load = C4ma (sourcing) l v cc2 C 0.4 v v ol logic output low voltage r1out, r2out i load = 1ma (sinking), 1.62v v l < 3.0v i load = 4ma (sinking), 3.0v v l 5.5v l l 0.4 0.4 v v dout, i load = 4ma (sinking) l 0.4 v esd (hbm) (note 2) rs232 driver and receiver protection (t1out, t2out, r1in, r2in) to (v cc2 , gnd2) 10 kv (t1out, t2out, r1in, r2in) to (v cc , v l , gnd) 10 kv isolation boundary (v cc2 , gnd2) to (v cc , v l , gnd) 10 kv
LTM2882 4 2882p switching characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. LTM2882-3 v cc = 3.3v, LTM2882-5 v cc = 5.0v, v l = v cc , and gnd = gnd2 = 0v, on = v l unless otherwise noted. symbol parameter conditions min typ max units maximum data rate (t1in to t1out, t2in to t2out) r l = 3k, c l = 2.5nf (note 3) l 100 kbps r l = 3k, c l = 1nf (note 3) l 250 kbps r l = 3k, c l = 250pf (note 3) l 1000 kbps maximum data rate (din to dout) c l = 15pf l 10 mbps driver driver slew rate (6v/ t thl or t tlh )r l = 3k, c l = 50pf (figure 1) l 150 v/s t phld , t plhd driver propagation delay r l = 3k, c l = 50pf (figure 1) l 0.2 0.5 s t skewd driver skew |t phld C t plhd |r l = 3k, c l = 50pf (figure 1) 40 ns t pzhd , t pzld driver output enable time de = , r l = 3k, c l = 50pf (figure 2) l 0.6 2 s t phzd , t plzd driver output disable time de = , r l = 3k, c l = 50pf (figure 2) l 0.3 2 s receiver t phlr , t plhr receiver propagation delay c l = 150pf (figure 3) l 0.2 0.4 s t skewr receiver skew |t phlr C t plhr |c l = 150pf (figure 3) 40 ns t rr , t fr receiver rise or fall time c l = 150pf (figure 3) l 60 200 ns auxiliary channel t phll , t plhl propagation delay c l = 15pf, t r and t f < 4ns (figure 4) l 60 100 ns t rl , t fl rise or fall time c l = 150pf (figure 4) l 60 200 ns power supply power-up time on = to v cc2(min) l 0.2 2 ms isolation characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. LTM2882-3 v cc = 3.3v, LTM2882-5 v cc = 5.0v, v l = v cc , and gnd = gnd2 = 0v, on = v l unless otherwise noted. symbol parameter conditions min typ max units v iso rated dielectric insulation voltage 1 minute, derived from 1 second test 2500 v rms 1 second 4400 v common mode transient immunity (note 2) 30 kv/s v iorm maximum working insulation voltage (note 2) 560 v peak partial discharge v pr = 1050 v peak (note 2) <5 pc input to output resistance (note 2) >10 9 input to output capacitance (note 2) 6 pf creepage distance (note 2) 9.48 mm 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: guaranteed by design and not subject to production test. note 3: maximum data rate is guaranteed by other measured parameters and is not tested directly. note 4: this device includes over-temperature 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 speci? ed maximum operating junction temperature may result in device degradation or failure.
LTM2882 5 2882p typical performance characteristics v cc supply current vs load capacitance (dual transceiver) v cc supply current vs data rate (dual transceiver) driver short-circuit current vs temperature receiver input threshold vs temperature v cc supply current vs temperature v cc supply current vs temperature t a = 25c, LTM2882-3 v cc = 3.3v, LTM2882-5 v cc = 5v, v l = 3.3v, and gnd = gnd2 = 0v, on = v l unless otherwise noted. temperature (c) C50 v cc current (ma) 30 25 15 20 10 50 0 100 2882 g01 125 25 C25 75 no load v cc = 3.3v LTM2882-3 v cc = 5.0v LTM2882-5 temperature (c) C50 v cc current (ma) 70 60 40 35 45 55 65 50 30 50 0 100 2882 g02 125 25 C25 75 t1out and t2out baud = 100kbps r l = 3k, c l = 2.5nf v cc = 3.3v LTM2882-3 v cc = 5.0v LTM2882-5 load capacitance (nf) 0 v cc current (ma) 100 250kbps, LTM2882-3 100kbps, LTM2882-3 19.2kbps, LTM2882-3 19.2kbps, LTM2882-5 250kbps, LTM2882-5 100kbps, LTM2882-5 80 40 50 30 70 90 60 20 12 2882 g03 2.5 0.5 1.5 data rate (kbps) 0 v cc current (ma) 140 100 40 80 120 60 20 400 800 2882 g04 1000 200 600 5.0v c l = 1nf 5.0v c l = 250pf 3.3v c l = 1nf 3.3v c l = 250pf temperature (c) C50 threshold voltage (v) 3.0 2.0 0.5 1.5 2.5 1.0 0 50 0 100 2882 g05 125 input low 25 C25 75 input high load capacitance (nf) 0 slew rate (v/s) 70 50 10 20 40 60 30 0 4 2 2882 g06 5 3 1 falling rising temperature (c) C50 short-circuit current (ma) 50 40 25 20 15 35 45 30 10 0 50 75 100 2882 g07 125 C25 25 sourcing sinking driver slew rate vs load capacitance receiver output voltage vs load current load current(ma) 0 output voltage (v) 6 1 2 4 5 3 0 8 4 2882 g09 10 6 2 v l = 5.5v v l = 3.3v v l = 1.62v driver disabled leakage current vs temperature at 15v temperature (c) C50 leakage current (na) 1000 10 0.01 1 100 0.1 0.001 0 50 75 100 2882 g08 125 C25 25 v tout = 15v
LTM2882 6 2882p typical performance characteristics driver outputs exiting shutdown driver outputs enable/disable logic input threshold vs v l supply voltage t a = 25c, LTM2882-3 v cc = 3.3v, LTM2882-5 v cc = 5v, v l = 3.3v, and gnd = gnd2 = 0v, on = v l unless otherwise noted. v l supply voltage (v) 0 threshold voltage (v) 3.5 2.5 0.5 1.0 2.0 3.0 1.5 0 45 2 2882 g10 6 3 1 input high input low 100s/div 5v/div t1out t1out on t2out t2out 2882 g12 de = v cc2 de = dout, d in = v l 2s/div 5v/div 2v/div t1out t2out 2882 g13 de operating through 35kv/s common mode transients 50ns/div 500v/div 2v/div t1in r1out * * multiple sweeps of common mode transients 2v/div 2882 g14 t1out = r1in v cc2 output voltage vs load current load current (ma) 0 v cc2 voltage (v) 5.2 5.0 4.6 4.7 4.9 5.1 4.8 4.5 150 50 250 2882 g11 300 3.0v 100 200 v cc = 3.0v to 3.6v, LTM2882-3 v cc = 4.5v to 5.5v, LTM2882-5 5.5v 5.0v 4.5v 3.6v 3.3v
LTM2882 7 2882p v cc2 load step response 100s/div 50ma/div 200mv/div 2882 g18 v cc2 ripple and noise v cc2 power ef? ciency 10s/div 100mv/div 2882 g17 t1in = 250kbps t1out, t2out, r l = 3k load current (ma) 0 efficiency (%) power loss (w) 70 60 20 30 50 40 10 1.2 1.0 0.2 0.4 0.8 0.6 0 200 250 100 2882 g16 300 150 50 LTM2882-3 LTM2882-5 t a = 25c typical performance characteristics t a = 25c, LTM2882-3 v cc = 3.3v, LTM2882-5 v cc = 5v, v l = 3.3v, and gnd = gnd2 = 0v, on = v l unless otherwise noted. v cc2 surplus current vs temperature temperature (c) C50 v cc2 current (ma) 300 200 50 150 250 100 0 50 0 100 2882 g15 125 25 C25 75 t1out and t2out baud = 100kbps r l = 3k, c l = 2.5nf v cc2 = 4.8v v cc = 3.3v LTM2882-3 v cc = 5.0v LTM2882-5
LTM2882 8 2882p test circuits figure 3. receiver timing measurement figure 4. auxiliary channel timing measurement 2882 f03 rin rout c l t phlr t plhr t fr t rr 10% ?v l 90% 90% 10% 1.5v 3v v ol v oh C3v rin rout t r ,t f 40ns 2882 f04 din dout c l t plhl t phll t rl t fl 90% 10% 10% 90% ?v l ?v cc2 v l v oh v ol 0v din dout figure 1. driver slew rate and timing measurement figure 2. driver enable/disable times 2882 f01 r l tin tout c l t plhd t phld t thl t tlh 3v 0v C3v ?v l v l v old v ohd 0v tin tout t r ,t f 40ns 2882 f02 r l de tout t r ,t f 40ns 0 or v l c l t pzhd t pzld t phzd t plzd v old C 0.5v v ohd C 0.5v ?v cc2 v cc2 v ohd v old 0v 0v 0v tout tout de C5v 5v
LTM2882 9 2882p logic side r2out (pin a1): channel 2 rs232 inverting receiver output. controlled through isolation barrier from receiver input r2in. under the condition of an isolation communi- cation failure r2out is in a high impedance state. t2in (pin a2): channel 2 rs232 inverting driver input. a logic low on this input generates a high on isolated output t2out. a logic high on this input generates a low on isolated output t2out. do not ? oat. r1out (pin a3): channel 1 rs232 inverting receiver output. controlled through isolation barrier from receiver input r1in. under the condition of an isolation communi- cation failure r1out is in a high impedance state. t1in (pin a4): channel 1 rs232 inverting driver input. a logic low on this input generates a high on isolated output t1out. a logic high on this input generates a low on isolated output t1out. do not ? oat. din (pin a5): general purpose non-inverting logic input. a logic high on din generates a logic high on isolated output dout. a logic low on din generates a logic low on isolated output dout. do not ? oat. on (pin a6): enable. enables power and data communica- tion through the isolation barrier. if on is high the part is enabled and power and communications are functional to the isolated side. if on is low the logic side is held in reset and the isolated side is unpowered. do not ? oat. v l (pin a7): logic supply. interface supply voltage for pins din, r2out, t2in, r1out, t1in, and on. operating voltage is 1.62v to 5.5v. v cc (pins a8, b7-b8): supply voltage. operating volt- age is 3.0v to 3.6v for LTM2882-3, and 4.5v to 5.5v for LTM2882-5. gnd (pins b1-b6): circuit ground. isolated side gnd2 (pins k1-k7): isolated side circuit ground. these pads should be connected to the isolated ground and/or cable shield. v cc2 (pins k8, l7-l8): isolated supply voltage output. internally generated from v cc by an isolated dc/dc con- verter and regulated to 5v. supply voltage for pins r1in, r2in, de, and dout. r2in (pin l1): channel 2 rs232 inverting receiver input. a low on isolated input r2in generates a logic high on r2out. a high on isolated input r2in generates a logic low on r2out. impedance is nominally 5k in receive mode or unpowered. t2out (pin l2): channel 2 rs232 inverting driver output. controlled through isolation barrier from driver input t2in. high impedance when the driver is disabled (de pin is low). r1in (pin l3): channel 1 rs232 inverting receiver input. a low on isolated input r1in generates a logic high on r1out. a high on isolated input r1in generates a logic low on r1out. impedance is nominally 5k in receive mode or unpowered. t1out (pin l4): channel 1 rs232 inverting driver output. controlled through isolation barrier from driver input t1in. high impedance when the driver is disabled (de pin is low). dout (pin l5): general purpose non-inverting logic output. logic output connected through isolation barrier to din. de (pin l6): driver output enable. a low input forces both rs232 driver outputs, t1out and t2out, into a high impedance state. a high input enables both rs232 driver outputs. do not ? oat. pin functions
LTM2882 10 2882p block diagram 2882 bd 2.2f 2.2f v cc v cc2 gnd2 de dout t1out r1in t2out r2in v l 2.2f gnd on din t1in t2in r2out r1out dc/dc converter isolated communi- cations interface isolated communi- cations interface 5v reg v dd v ee v dd v dd v ee v ee 5k 5k
LTM2882 11 2882p figure 5. v cc and v l are independent 2882 f05 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 any voltage from 1.62v to 5.5v 3.0v to 3.6v LTM2882-3 4.5v to 5.5v LTM2882-5 external device v l v cc v cc2 gnd isolation barrier gnd2 applications information overview the LTM2882 module transceiver provides a galvani- cally-isolated robust rs232 interface, powered by an integrated, regulated dc/dc converter, complete with decoupling capacitors. the LTM2882 is ideal for use in networks where grounds can take on different voltages. isolation in the LTM2882 blocks high voltage differences, eliminates ground loops and is extremely tolerant of com- mon mode transients between grounds. error-free opera- tion is maintained through common mode events greater than 30kv/s providing excellent noise isolation. module technology the LTM2882 utilizes isolator module technology to translate signals and power across an isolation barrier. signals on either side of the barrier are encoded into pulses and translated across the isolation boundary using coreless transformers formed in the module substrate. this system, complete with data refresh, error checking, safe shutdown on fail, and extremely high common mode immunity, provides a robust solution for bidirectional signal isolation. the module technology provides the means to combine the isolated signaling with our advanced dual rs232 transceiver and powerful isolated dc/dc converter in one small package. dc/dc converter the LTM2882 contains a fully integrated isolated dc/dc converter, including the transformer, so that no external components are necessary. the logic side contains a full- bridge driver, running at about 2mhz, and is ac-coupled to a single transformer primary. a series dc blocking capacitor prevents transformer saturation due to driver duty cycle imbalance. the transformer scales the primary voltage, and is recti? ed by a full-wave voltage doubler. this topology eliminates transformer saturation caused by secondary imbalances. the dc/dc converter is connected to a low dropout regulator (ldo) to provide a regulated low noise 5v output, v cc2 . an integrated boost converter generates a 7v v dd supply and a charge pumped C6.3v v ee supply. v dd and v ee power the output stage of the rs232 drivers and are regulated to levels that guarantee greater than 5v output swing. the internal power solution is suf? cient to support the transceiver interface at its maximum speci? ed load and data rate, and has the capacity to provide additional 5v power on the isolated side v cc2 and gnd2 pins. v cc and v cc2 are each bypassed internally with 2.2f ceramic capacitors. v l logic supply a separate logic supply pin v l allows the LTM2882 to inter- face with any logic signal from 1.62v to 5.5v as shown in figure 5. simply connect the desired logic supply to v l . there is no interdependency between v cc and v l ; they may simultaneously operate at any voltage within their speci? ed operating ranges and sequence in any order. v l is bypassed internally by a 2.2f capacitor. hot plugging safely caution must be exercised in applications where power is plugged into the LTM2882s power supplies, v cc or v l , due to the integrated ceramic decoupling capacitors. the parasitic cable inductance along with the high q char- acteristics of ceramic capacitors can cause substantial ringing which could exceed the maximum voltage ratings and damage the LTM2882. refer to linear technology ap- plication note 88, entitled ceramic input capacitors can cause overvoltage transients for a detailed discussion and mitigation of this phenomenon.
LTM2882 12 2882p channel timing uncertainty multiple channels are supported across the isolation bound- ary by encoding and decoding of the inputs and outputs. the technique used assigns t1in/r1in the highest priority such that there is no jitter on the associated output chan- nels t1out/r1out, only delay. this preemptive scheme will produce a certain amount of uncertainty on t2in/r2in to t2out/r2out and din to dout. the resulting pulse width uncertainty on these low priority channels is typically 6ns, but may vary up to about 40ns. half-duplex operation the de pin serves as a low-latency driver enable for half- duplex operation. the de pin can be easily driven from the logic side by using the uncommitted auxiliary digital channel, din to dout. each driver is enabled and disabled in less than 2s, while each receiver remains continuously active. this mode of operation is illustrated in figure 6. applications information figure 6. half-duplex con? guration using d out to drive de 2882 f06 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 3.3v (LTM2882-3) 5v (LTM2882-5) v l v cc v cc2 gnd gnd2 isolation barrier t x r x driver overvoltage and overcurrent protection the driver outputs are protected from short-circuits to any voltage within the absolute maximum range of 15v relative to gnd2. the maximum current is limited to no more than 70ma to maintain a safe power dissipation and prevent damaging the LTM2882. receiver overvoltage and open circuit the receiver inputs are protected from common mode voltages of 25v relative to gnd2. each receiver input has a nominal input impedance of 5k relative to gnd2. an open circuit condition will generate a logic high on each receivers respective output pin. rf, magnetic field immunity the LTM2882 has been independently evaluated and has successfully passed the rf and magnetic ? eld immunity testing requirements per european standard en 550024, in accordance with the following test standards: en 61000-4-3 radiated, radio-frequency, electromagnetic field immunity en 61000-4-8 power frequency magnetic field immunity en 61000-4-9 pulsed magnetic field immunity tests were performed using an unshielded test card de- signed per the data sheet pcb layout recommendations. speci? c limits per test are detailed in table 1. table 1 test frequency field strength en 61000-4-3, annex d 80mhz to 1ghz 10v/m 1.4mhz to 2ghz 3v/m 2ghz to 2.7ghz 1v/m en61000-4-8, level 4 50hz and 60hz 30a/m en61000-4-8, level 5 60hz 100a/m* en61000-4-9, level 5 pulse 1000a/m *non iec method
LTM2882 13 2882p applications information pcb layout the high integration of the LTM2882 makes pcb layout very simple. however, to optimize its electrical isolation characteristics, emi, and thermal performance, some lay- out considerations are necessary. figure 7 is a suggested layout for good thermal performance and to optimize isolation characteristics. ? under heavily loaded conditions, the current in v cc and gnd can exceed 300ma. pcb copper must be made wide enough in these paths to ensure resistive losses do not cause the supply voltage at the LTM2882 to drop below the minimum allowed levels. similarly, the metal in the v cc2 and gnd2 must be wide enough to support any external load connected. ? input and output decoupling is not required, since these components are integrated within the package. if additional capacitance is used, place as close to the power and ground terminals as possible to minimize high frequency noise. for emi sensitive applications, an additional low esr capacitance of 6.8f to 22f is recommended from v cc to gnd. ? do not place copper on the pcb between the inner col- umns of pads. this area must remain open to withstand the rated isolation voltage. the pcb may also be slotted in this area to facilitate cleaning and ensure contamina- tion does not compromise the isolation voltage. ? the recommended layout of figure 7 shows copper planes for gnd and gnd2, which is good practice to optimize signal ? delity and minimize emissions on either side of the isolation boundary. however, this creates a dipole antenna which can radiate differential voltages formed between gnd and gnd2. a small capacitance (<200pf) from gnd to gnd2, either discrete or embed- ded within the substrate, provides a low impedance path minimizing the high frequency differential voltages and substantially reducing radiated emissions. care should be exercised in applying these techniques to insure the voltage rating of the isolation barrier is not compromised. figure 7. recommended pcb layout v cc v cc2 v l on din t1in r1out t2in de dout t1out r1in t2out r2in r2out slot top copper gnd2 gnd slot bottom copper
LTM2882 14 2882p typical applications figure 8. single line dual half-duplex isolated transceiver 2882 f08 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 3.3v (LTM2882-3) 5v (LTM2882-5) v l v cc gnd gnd2 3.3k isolation barrier t x r x 3.3k figure 12. isolated multirail power supply with switched outputs 2882 f12 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 3.0v to 3.6v (LTM2882-3) 4.5v to 5.5v (LTM2882-5) 5v regulated 7v switched return C6.3v switched v l v cc v cc2 gnd gnd2 isolation barrier on off figure 9. driving larger capacitive loads figure 10. 1.8v microprocessor interface 2882 f09 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 3.3v (LTM2882-3) 5v (LTM2882-5) v l v cc gnd gnd2 isolation barrier 3k c l data rate (kbps) 100 5 250 2 1000 0.5 c l (nf) 2882 f10 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 p v l v cc gnd 1.8v 3.3v (LTM2882-3) 5v (LTM2882-5) isolation barrier gnd2 figure 11. isolated 5v power supply 2882 f11 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 v l v cc v cc2 gnd 3.3v (LTM2882-3) 5v (LTM2882-5) 5v regulated 150ma (LTM2882-5) 100ma (LTM2882-3) isolation barrier gnd2 on off
LTM2882 15 2882p 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 lga package 32-lead (15mm 11.25mm 2.82mm) (reference ltc dwg # 05-08-1773 rev ?) notes: 1. dimensioning and tolerancing per asme y14.5m-1994 2. all dimensions are in millimeters land designation per jesd mo-222 5. primary datum -z- is seating plane 6. the total number of pads: 32 4 3 details of pad #1 identifier are optional, but must be located within the zone indicated. the pad #1 identifier may be either a mold or marked feature detail b detail b substrate mold cap 0.290 C 0.350 2.400 C 2.600 bbb z z package top view 11.25 bsc 15.00 bsc 4 pad a1 corner x y aaa z aaa z package bottom view 3 pads see notes suggested pcb layout top view lga 32 0308 rev ? ltmxxxxxx module tray pin 1 bevel package in tray loading orientation component pin a1 8.89 bsc 1.27 bsc pad 1 0.635 0.635 1.905 1.905 3.175 3.175 4.445 4.445 6.350 6.350 5.080 5.080 0.000 symbol aaa bbb eee tolerance 0.10 0.10 0.05 detail a 0.630 0.025 ? 32x s y x eee detail c 0.630 0.025 ? 32x s y x eee f g h l j k e a b c d 21 43 5 6 7 2.69 C 2.95 detail a 12.70 bsc 8 detail c
linear technology confidential LTM2882 16 2882p linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2009 lt 1209 ? printed in usa related parts typical applications part number description comments ltm2881 isolated rs485/rs422 module transceiver with integrated dc/dc converter 20mbps, 15kv hbm esd, 2500v rms isolation with power ltc2804 1mbps rs232 transceiver dual channel, full-duplex, 10kv hbm esd ltc1535 isolated rs485 transceiver 2500 v rms isolation with external transformer driver figure 15. isolated gate drive with overcurrent detection figure 13. isolated rs232 interface with handshaking figure 14. isolated dual inverting level translator 2882 f14 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 v l v cc v cc2 gnd gnd2 +v s 3k irlml2402 irlml6402 470pf 1k 1k 3.3v (LTM2882-3) 5v (LTM2882-5) isolation barrier reset fault pwma pwmb r ilim = 0.6/max current 47pf cmpt2369-ltv 3k logic level fets 2882 f12 on din t1in r2out t2in r2out de dout t1out r1in t2out r2in LTM2882 c peripheral v l v cc r x t x rts cts t x d r x d p y p z v cc2 gnd gnd2 3.3v (LTM2882-3) 5v (LTM2882-5) isolation barrier 2882 f13 on din t1in r1out t2in r2out de dout t1out r1in t2out r2in LTM2882 v l v cc gnd 3.3v (LTM2882-3) 5v (LTM2882-5) gnd2 1.62v to 5.5v isolation barrier on off v l 0v v l 0v C25v to 0v 3v to 25v C25v to 0v 3v to 25v

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