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1 typical a pplica t ion fea t ures descrip t ion isolated usb transceiver with isolated power the lt m ? 2884 is a complete galvanically isolated usb 2.0 compatible module ? ( micromodule) transceiver . an upstream supply powers both sides of the interface through an integrated, isolated dc/dc converter. the LTM2884 is ideal for isolation in host, hub, bus split - ter or peripheral device applications. it is compatible with usb 2.0 full speed (12 mbps) and low speed (1.5mbps) operation. automatic speed selection configures integrated pull-up resistors on the upstream port to match those sensed on the downstream device. the isolator module technology uses coupled inductors and an isolated power transformer to provide 2500v rms of isolation between the upstream and downstream usb interface. this device is ideal for systems requiring isolated ground returns or large common mode voltage variations. uninterrupted communication is guaranteed for common mode transients greater than 30kv/s. enhanced esd protection allows this part to withstand up to 15kv ( human body model) on the usb transceiver interface pins to local supplies and 15 kv through the isolation barrier to supplies without latch-up or damage. powered 2.5w isolated hub port a pplica t ions n isolated usb transceiver: 2500v rms for 1 minute n usb 2.0 full speed and low speed compatible n integrated isolated dc/dc converter, external or bus powered n auto-configuration of bus speed n 2.5w (500ma at 5v) output power from external input supply (v cc = 8.6v to 16.5v) n 1w (200ma at 5v) output power from usb bus supply (v bus ) n 3.3v ldo output supply signal references v lo , v lo2 n high common mode transient immunity: 30kv/s n esd: 15kv hbm on usb interface pins n 15 mm 15mm 5mm surface mount bga package n isolated usb interfaces n host, hub, or device isolation n industrial/medical data acquisition l, lt , lt c , lt m , linear technology, the linear logo and module are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. bus powered 1w isolated peripheral device 2884 ta01a isolation barrier v lo LTM2884 500ma at 5v on 4.4v to 16.5v v bus v bus2 8.6v to 16.5v 100f v cc spndpwr d1 + d1 ? v cc2 v lo2 d2 + downstream usb port d2 ? gnd2 gnd 15k 15k + pwr hub c 2884 ta01b v lo on spndpwr v cc2 v bus v bus gnd gnd2 gnd upstream usb port v cc isolation barrier LTM2884 200ma at 5v d1 + peripheral d1 ? v lo2 d2 + d2 ? pwr 1.5k 2884f for more information www.linear.com/LTM2884 LTM2884
2 p in c on f igura t ion a bsolu t e maxi m u m r a t ings supply voltages v cc to gnd ............................................ C 0.3 v to 18 v v bus to gnd .......................................... C 0.3 v to 18 v v cc 2 to gnd 2 ....................................... C 0.3 v to 10 v v lo to gnd .................................................. C 0.3 v to 4v v lo2 to gnd 2 ............................................... C 0.3 v to 4v on , spndpwr to gnd ................. C 0.3 v to (v lo + 0.3 v) d1 + , d1 C to gnd ........................................ C 0.3 v to 5.3 v d2 + , d2 C to gnd 2 ..................................... C 0.3 v to 5.3 v operating ambient temperature range ( note 3) ltm 28 84 c ............................................... 0 c to 70 c ltm 28 84 i ............................................ C4 0 c to 85 c ltm 28 84 h ......................................... C 40 c to 105 c storage temperature range .................. C 40 c to 125 c maximum internal operating temperature ............ 12 5 c peak body reflow temperature ............................ 24 5 c (note 1) bga package 44-lead (15mm 15mm 5mm) top view 21 43 5 6 7 8 9 1110 d1 ? d1 + spnd- pwr on v lo v bus v cc gnd d2 ? d2 + v lo2 v cc2 gnd2 gnd2 gnd gnd2 f g h l j k e a b c d t jmax = 125c, pcb = jesd51-9 2s2p: ja = 18.7c/w, jctop = 16c/w, jcbottom = 5.7c/w, jb = 5.6c/w pcb = dc1746a: ja = 33.5c/w, jctop = 15.7c/w, jcbottom = 6.1c/w, jb = 5.3c/w heat flow: ja = normal, jctop = 100%, jcbottom = 100%, jb = 100% weight = 2.4g o r d er i n f or m a t ion part number pad or ball finish part marking package type msl ra ting temperature range device finish code LTM2884cy#pbf sac305 (rohs) LTM2884y e1 bga 4 0c to 70c LTM2884iy#pbf C40c to 85c LTM2884hy#pbf C40c to 105c ? device temperature grade is indicated by a label on the shipping container. ? pad or ball finish code is per ipc/jedec j-std-609. ? terminal finish part marking: www.linear.com/leadfree ? this product is not recommended for second side reflow. for more information, go to: www.linear.com/bga-assy ? recommended bga pcb assembly and manufacturing procedures: www.linear.com/bga-assy ? bga package and t ray drawings: www.linear.com/packaging ? this product is moisture sensitive. for more information, go to: www.linear.com/bga-assy 2884f for more information www.linear.com/LTM2884 LTM2884
3 e lec t rical c harac t eris t ics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c . v cc = 5v , v bus = 5v , gnd = gnd2 = 0v , on = v lo , unless otherwise noted. symbol parameter conditions min typ max units power supply v cc operating supply range (isolated power input) l 4.4 12 16.5 v v bus operating supply range (usb bus power input) l 4.4 5 16.5 v v cc supply current power off on = 0v, v cc = 4.4v to 16.5v l 100 500 a i cc v cc supply current power on i cc2 = 0ma, figure 1 l 50 100 ma v bus supply current power off on = 0v l 10 100 a i bus v bus supply current power on i vlo = 0ma, figure 1 l 6 9 ma v bus supply current suspend mode spndpwr = 3.3v usb suspend timeout spndpwr = 0, usb suspend timeout l l 1.5 500 2.0 a ma v cc2 regulated v cc2 output voltage, loaded v cc = 4.4v, i cc2 = 200ma, figure 1 v cc = 8.6v, i cc2 = 500ma, figure 1 l l 4.75 4.75 5 5 5.25 5.25 v v v cc2 source current high power mode v cc = 8.6v, figure 1 l 500 ma v cc2 source current bus power mode v cc = v bus = 4.4v, figure 1 l 200 ma v lo v lo regulated output voltage i vlo = 0ma to 10ma, figure 1 l 3.15 3.3 3.45 v v lo output voltage maximum current figure 1 l 10 ma v lo2 v lo2 regulated output voltage i vlo2 = 0ma to 10ma, figure 1 l 3.15 3.3 3.45 v v lo2 output voltage maximum current figure 1 l 10 ma usb input levels (d1 + , d1 C , d2 + , d2 C ) v ih single-ended input high voltage l 2.0 v v il single-ended input low voltage l 0.8 v v hys single-ended input hysteresis 200 mv v diff differential input sensitivity |(d1 + C d1 C )| or |(d2 + C d2 C )| l 0.2 v v cm common mode voltage range |(d1 + + d1 C )|/2 or |(d2 + + d2 C )|/2 l 0.8 2.5 v logic input levels (on, spndpwr) v ihl logic input high voltage l 2.0 v v ill logic input low voltage l 0.8 v i inl logic input current l 1 a v hysl logic input hysteresis 200 mv usb output levels (d1 + , d1 C , d2 + , d2 C ) v ol output low voltage r pu = 1.5k to 3.6v, figure 4 l 0 0.3 v v oh output high voltage r pd = 15k to 0v, figure 4 l 2.8 3.6 v v crs differential output signal cross-point voltage l 1.3 2.0 v terminations r pu bus pull-up resistance on upstream facing port d2 + or d2 C pull-up to 3.3v 1.425 1.575 k r pd bus pull-down resistance on downstream facing port d2 + and d2 C pull-down to gnd2 14.25 15.75 k z drv usb driver output resistance l 28 44 c inusb usb transceiver pad capacitance to gnd (note 2) 10 pf 2884f for more information www.linear.com/LTM2884 LTM2884
4 s wi t ching c harac t eris t ics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c . v cc = 5v , v bus = 5v , gnd = gnd2 = 0v , on = v lo , unless otherwise noted. symbol parameter conditions min typ max units low speed usb t ldr low speed data rate c l = 50pf to 450pf (note 4) 1.5 mbps t lr rise time figure 2, c l = 50pf to 600pf l 75 300 ns t lf fall time figure 2, c l = 50pf to 600pf l 75 300 ns t lprr , t lpff propagation delay figure 2, c l = 50pf to 600pf l 200 300 ns t ldj1 differential jitter to next transition (note 2) 45 ns t ldj2 differential jitter to paired transitions (note 2) 15 ns full speed usb t fdr full speed data rate c l = 50pf (note 4) 12 mbps t fr rise time figure 3, c l = 50pf l 4 20 ns t ff fall time figure 3, c l = 50pf l 4 20 ns t fprr , t fpff propagation delay figure 3, c l = 50pf l 60 80 115 ns t fdj1 differential jitter to next transition (note 2) 2 ns t fdj2 differential jitter to paired transitions (note 2) 1 ns power supply generator v cc2 C gnd2 supply start-up time (on v lo , v cc2 to 4.5v) r load = 50, c load = 100f r load = 10, c load = 100f, v cc = 12v l l 2 3 5 10 ms ms t wuspnd wake up from suspend mode resume signal, spndpwr = 0 l 0.25 10 s esd (hbm) (note 2) isolation barrier gnd to gnd2 15 kv d1 + , d1 C , d2 + , d2 C d1 + /d1 C to gnd, v cc , v bus , or v lo and d2 + /d2 C to gnd2, v cc2 , or v lo2 15 kv on, spndpwr 3 kv i sola t ion c harac t eris t ics t a = 25c. symbol parameter conditions min typ max units isolation barrier: gnd to gnd2 v iso rated dielectric insulation voltage (notes 6, 7) 1 minute (derived from 1 second test) 2500 v rms 1 second (note 5) 3000 v rms common mode transient immunity v bus = v cc = 5v, on = 3.3v, 1000v in 33ns transient between gnd and gnd2 (note 2) 30 kv/s v iorm maximum working insulation voltage (notes 2, 5) 560 400 v peak v rms partial discharge v pr = 750v rms (note 5) <5 pc cti comparative tracking index iec 60112 (note 2) 600 v rms depth of erosion iec 60112 (note 2) 0.017 mm dti distance through insulation (note 2) 0.1 mm input to output resistance (notes 2, 5) 10 12 input to output capacitance (notes 2, 5) 13 pf creepage distance (notes 2, 5) 9.48 mm 2884f for more information www.linear.com/LTM2884 LTM2884
5 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 production tested. note 3: this module transceiver includes over temperature protection that is intended to protect the device during momentary overload conditions. junction temperature will exceed 125c when over temperature protection is active. continuous operation above specified maximum operating junction temperature may result in device degradation or failure. note 4: maximum data rate is guaranteed by other measured parameters and is not directly tested. note 5: device considered a 2-terminal device. measurement between groups of pins a1 through b11 shorted together and pins k1 through l11 shorted together. note 6: the rated dielectric insulation voltage should not be interpreted as a continuous voltage rating. note 7: in accordance with ul1577, each device is proof tested for the 2500v rms rating by applying the equivalent positive and negative peak voltage multiplied by an acceleration factor of 1.2 for one second. e lec t rical c harac t eris t ics 2884f for more information www.linear.com/LTM2884 LTM2884
6 typical p er f or m ance c harac t eris t ics low speed differential jitter v cc2 output current vs temperature v cc to v cc2 efficiency and power loss v cc input current vs v cc2 output current v cc2 output voltage vs load current full speed propagation delay vs temperature low speed propagation delay vs temperature full speed differential jitter t a = 25c, v cc = 5v, v bus = 5v, gnd = gnd2 = 0v, on = 3.3v, unless otherwise noted. temperature (c) ?50 propagation delay (ns) 100 95 75 90 85 80 70 50 0 100 2884 g01 125 25 ?25 75 c load = 120pf temperature (c) ?50 propagation delay (ns) 250 240 230 220 210 200 50 0 100 2884 g02 125 25 ?25 75 c load = 120pf 10ns/div 1v/div 2884 g03 jitter 1.4ns p-p d1 ? d1 + d2 ? d2 + 50ns/div 1v/div 2884 g04 jitter 7.5ns p-p d1 + d1 ? d2 + d2 ? temperature (c) ?50 output current (ma) 800 600 700 500 400 300 200 50 0 100 2884 g05 125 25 ?25 75 v cc = 12v v cc = 5v v cc2 = 4.75v output current (a) 0 input current (ma) 450 350 400 300 150 200 100 250 50 0 0.2 0.6 2884 g07 0.8 0.4 v cc = 12v v cc = 5v load current (a) 0 v cc2 (v) 5.25 4.75 5.00 4.50 4.25 4.00 0.4 0.2 0.8 2884 g08 1.0 0.6 v cc = 5v v cc = 4.4v v cc = 8.1v v cc = 12v i out (a) 0 efficiency (%) power loss (w) 70 50 60 40 30 20 0 1.4 1.2 0.8 1.0 0.6 0.4 0.2 0 0.2 0.6 2884 g06 0.8 0.4 v cc = 5v v cc = 5v v cc = 12v v cc = 12v power loss efficiency derating for 125c maximum internal operating temperature temperature (c) 25 load current (a) 0.55 0.45 0.50 0.40 0.25 0.15 0.20 0.35 0.30 0.10 0.05 0 4535 55 7565 9585 115 2884 g09 125 105 v bus ? v cc = 5v v bus ? v cc = 8.6v v bus ? v cc = 12v v bus ? v cc = 16.5v 2884f for more information www.linear.com/LTM2884 LTM2884
7 typical p er f or m ance c harac t eris t ics v cc2 = load step response, 0ma to 500ma (v cc = 12v) v cc2 = load step response, 0ma to 200ma (v cc = 5v) i cc vs temperature upstream v bus droop during plug-in with c load = 100f full speed data start of packet v cc2 ripple, v cc = 5v, i cc2 = 200ma v cc2 start-up ramp t a = 25c, v cc = 5v, v bus = 5v, gnd = gnd2 = 0v, on = 3.3v, unless otherwise noted. 2s/div 100mv/div 2884 g10 v cc2 ripple, v cc = 12v, i cc2 = 500ma 100s/div 500mv/div 200ma/div 2884 g13 v cc2 i cc2 100s/div 500mv/div 200ma/div 2884 g14 v cc2 i cc2 temperature (c) ?50 supply current (ma) 70 30 60 20 50 40 10 0 ?25 25 50 75 100 2884 g15 125 0 v cc = 12.5v v cc = 16.5v v cc = 5v v cc = 8.1v v cc = 4.4v i cc2 = 0ma 500s/div 1v/div 2884 g16 isolated v cc2 host v bus plug in to host 100ns/div 500mv/div 2884 g17 d2 + d2 ? 2s/div 100mv/div 2884 g11 500s/div 1v/div 2884 g12 on v cc2 v cc2 droop/plug-in response 200s/div 1v/div 2884 g16 v cc v cc2 2884f for more information www.linear.com/LTM2884 LTM2884
8 p in func t ions upstream side (v cc , v bus , v lo , gnd) d1 C ( a 1): usb data bus upstream facing negative transceiver pin. a 1.5 k pull-up resistor is automatically configured to indicate the idle condition of the d2 C pin. d1 + ( a 2): usb data bus upstream facing positive transceiver pin. a 1.5 k pull-up resistor is automatically configured to indicate the idle condition of the d2 + pin. spndpwr (a3): suspend power control. a high input enables the dc/dc converter shutdown control if the usb bus is suspended. a low input ( gnd) disables the shut - down control to the dc/dc converter maintaining power to the isolated downstream side during suspend mode. the recovery time from suspend mode may be equivalent to the power supply start-up time if the dc/dc converter was shut down. the spndpwr pin is referenced to v lo and gnd. on (a4): enable for power and data communication through the isolation barrier. if on is high, the part is enabled. if on is low, the upstream side is held in reset and the isolated side is unpowered by the dc/ dc converter. the on pin is referenced between v lo and gnd. v lo (a5): internally regulated 3.3 v logic voltage output. the v lo pin is used as a positive reference for the on and spndpwr pins and can source up to 10 ma of surplus current. internally bypassed to gnd with 2.2 f. output supply, no external connection necessary. gnd (a6, b1-b11): upstream circuit ground. v bus ( a7): voltage supply input to usb transceiver. the operating range is 4.4 v to 16.5 v. connect to the usb v bus supply or an external source. internally bypassed to gnd with 2.2f. v cc (a8-a11): voltage supply input to dc/dc converter. the operating range is 4.4 v to 16.5v . connect to an external supply greater than 8.6 v for 500 ma on v cc2 . connect to the usb v bus for up to 200 ma on v cc2 . connect v cc to v bus when the peripheral device has an external power source. internally bypassed to gnd with 4.7f. isolated downstream side (v cc2 , v lo2 , gnd2) gnd2 ( k1-k11, l3, l4, l6, l7): downstream circuit ground. d2 C (l1): usb data bus downstream facing negative transceiver pin. the pin has a 15 k pull-down resistor to gnd2. d2 + ( l 2): usb data bus downstream facing positive trans - ceiver pin . the pin has a 15 k pull-down resistor to gnd2. v lo2 (l5): internally regulated 3.3 v logic voltage output. the v lo2 pin can source up to 10 ma of surplus current. internally bypassed to gnd2 with 2.2 f. output supply, no external connection necessary. v cc2 (l8-l11): isolated voltage supply output from dc/ dc converter. output voltage is 5 v and can support up to 500ma of peripheral device current referenced to gnd2. output current is dependant on input supply voltage and current limit. internally bypassed to gnd2 with 22f. output supply, no external connection necessary. 2884f for more information www.linear.com/LTM2884 LTM2884
9 b lock diagra m 2884 bd 22f d2 + v lo2 v cc2 15k gnd2 gnd = upstream side common = downstream side common 15k downstream port d2 ? 4.7f v cc 2.2f 3.3v reg 3.3v reg isolated communication interface isolated communication interface 2.2f v bus v lo on d1 + d1 ? 2.2f dc/dc spndpwr upstream port 1.5k 1.5k 2884f for more information www.linear.com/LTM2884 LTM2884
10 tes t c ircui t s 2884 f01 isolation barrier v cc i cc LTM2884 v bus v bus v lo i vlo gnd v cc2 v lo2 gnd2 i vlo2 i cc2 + ? v cc + ? i bus figure 1. power supply loads 2884f for more information www.linear.com/LTM2884 LTM2884
11 2884 f02 0v 3.3v 0v 3.3v d1 + or d2 + d2 + or d1 + c l d1 ? or d2 ? d2 ? or d1 ? 3.6v c l 1.5k t lr t lprr t lpff t lf 10% 10% 90% 90% d2 + or d1 + d2 ? or d1 ? d1 + or d2 + d1 ? or d2 ? 2884 f03 0v 3.3v 0v 3.3v d1 + or d2 + d2 + or d1 + c l d1 ? or d2 ? d2 ? or d1 ? c l t ff t fpff t fprr t fr 10% 10% 90% 90% d2 ? or d1 ? d2 + or d1 + d1 ? or d2 ? d1 + or d2 + figure 2. low speed timing measurements figure 3. full speed timing measurements tes t c ircui t s 2884f for more information www.linear.com/LTM2884 LTM2884
12 func t ional table usb transceiver functional table mode d1 + d1 C automatic pull-up connection d2 + d2 C spndpwr full speed (idle) 1.5k pull-up host pull-down d1 + peripheral pull-up 15k pull-down x low speed (idle) host pull-down 1.5k pull-up d1 C 15k pull-down peripheral pull-up x disconnected (idle) host pull-down host pull-down none 15k pull-down 15k pull-down x suspend (idle >3ms) set at device connect set at device connect set at device connect peripheral or 15k peripheral or 15k 0 suspend no power (idle >3ms) set at device connect set at device connect set at device connect 15k pull-down 15k pull-down 3.3v d1 to d2 data in + in C set at device connect out + out C x d2 to d1 data out + out C set at device connect in + in C x power functional table mode on spndpwr v cc v bus dc/dc converter off 0 x x x off on 3.3v x >4.4v >4.4v on on, suspend (idle >3ms) 3.3v 0 >4.4v >4.4v on on, suspend (idle >3ms), power off 3.3v 3.3v >4.4v >4.4v off on, usb transceiver only power off 3.3v x 0 >4.4v off 2884f for more information www.linear.com/LTM2884 LTM2884
13 the LTM2884 module transceiver provides a galvanically isolated robust usb interface, powered by an integrated, regulated dc/dc converter, complete with decoupling capacitors. this flexible device can support a variety of usb configurations, either bus powered or externally powered. applications include isolation in hosts, hubs, peripherals, or standalone inline bus splitters. automati - cally configured pull - up resistors are included to represent the condition of the isolated downstream usb bus to the upstream usb bus. the LTM2884 is ideal for use in usb connections where grounds between upstream hub/host and downstream devices can take on different voltages. isolation in the LTM2884 blocks high voltage differences and eliminates ground loops and is extremely tolerant of common mode transients between ground potentials. error free operation is maintained through common mode events exceeding 30kv/s providing excellent noise isolation. the LTM2884 contains a fully integrated dc/dc converter including the transformer, so that no external components are necessary in many configurations. the upstream side contains a flyback converter that regulates the downstream output voltage through primary sensing techniques. the internal power solution is sufficient to support the trans - ceiver inter face and supply up to 500 ma at 5 v through v cc2 to an attached device dependent on the supply voltage and available current on v cc . the integrated usb transceivers on both sides of the iso- lation barrier support full and low speed modes defined in the usb 2.0 specification. the communication through the isolation barrier for usb is bidirectional and as such the LTM2884 determines data flow direction based on which side a start of packet ( sop) begins first. the direction of data is maintained until an end of packet ( eop) pattern is observed or a timeout occurs due to a lack of activity . the usb interface maintains a consistent propagation delay representative of a hub delay and transfers all data. pull-up resistors integrated in the upstream interface automatically indicate device connections and discon - nections. a downstream device connection automatically selects the proper pull-up resistor at the upstream facing port after sensing the idle state of the downstream device at connection time. disconnection of a downstream device automatically releases the pull- up resistor on the upstream facing port allowing the upstream 15 k pull-down resistors to pull the bus signals to a disconnect condition. this func - tion makes the LTM2884 ideal for host, hub, bus splitter, or peripheral device integration. isolator module t echnology the LTM2884 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 us - ing differential signaling through 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 a usb transceiver and powerful isolated dc/dc converter in one small package. usb transceiver pin protection the LTM2884 usb transceiver pins d1 + , d1 C , d2 + , and d2 C have protection from esd and short-circuit faults. the transceiver pins withstand 15 kv hbm esd events. overcurrent circuitry on the transceiver pins monitor fault conditions from d1 + and d1 C to gnd, v lo , or v bus and from d2 + and d2 C to gnd2, v lo2 , or v cc2 . a current detection circuit disables the transceiver pin if the pin sinks about 40ma for greater than 600 ns. the v lo and v lo2 output supplies protect the usb transceiver pins from shorts to gnd or gnd2 respectively with a 40ma current limit. o pera t ion 2884f for more information www.linear.com/LTM2884 LTM2884
14 usb connectivity the LTM2884 module transceiver connects directly to usb ports on the upstream side and the downstream side without the addition of external components. the trans - ceiver passes through all data and does not act as a hub or intelligent device. the bus lines are monitored for idle conditions, start of packet, and end of packet conditions to properly maintain bus speed and data direction. the series resistance, pull-up, and pull-down resistors are built into the LTM2884. the upstream facing usb port contains automatically configured 1.5 k pull-up resistors which are switched in or out based on the downstream side peripheral device configuration. this implementation allows upstream reporting of the downstream bus speed and connection/ disconnection conditions. built - in 15 k pull- down resistors are included from the d2 + and d2 C signals to gnd2 supporting the downstream bus configuration. monitoring the usb data pins, the LTM2884 detects a k-state to begin a data packet and set the data direction. the data is monitored for an end of packet signature and a finishing j-state before the bus is released. the data pay - load between the k- state and j- state is transferred through the LTM2884 isolator with a delay of approximately 80ns. idle state communication and automatic speed selection the LTM2884 module transceiver maintains the condi- tions of the usb bus idle state by monitoring the down- stream side bus idle condition and refreshing the state across the isolation barrier at a consistent rate. further- more, the LTM2884 monitors the speed of the downstream peripheral once connected and sets its own operation to match. figure 4 shows the abbreviated circuitry of the automatic monitoring and reporting of the bus speeds. the d2 + or d2 C signals are monitored for a connection to pull-ups on d2 + or d2 C and the result is processed as full speed or low speed, otherwise disconnect. the idle state is communicated to the upstream side through a refresh transmission. the switches sw1 or sw2 are controlled based on the received information. sw1 is closed if d2 + is detected to have a pull-up and d2 C was open. sw2 is closed if d2 C is detected to have a pull-up and d2 + was open. both sw1 and sw2 are opened if the downstream usb bus is disconnected. during a usb suspend, the pull- up resistor will maintain the condition prior to detecting the suspend command. a pplica t ions i n f or m a t ion figure 4. idle state automatic resistor setting 2884 f04 isolation barrier LTM2884 refresh v lo d1 + r pu 1.5k r pu 1.5k sw1 sw2 d1 ? 15k 15k d2 + d2 ? r pd 15k r pd 15k 1.5k full speed upstream connection downstream connection or or disconnected low speed 1.5k 3.3v 3.3v 2884f for more information www.linear.com/LTM2884 LTM2884
15 a pplica t ions i n f or m a t ion suspend mode when the upstream usb bus is idle for greater than 3ms, the LTM2884 enters suspend mode . the power savings and behavior in suspend mode depend on the state of the spndpwr pin, as summarized in table 1. table 1. suspend mode operation spndpwr v cc2 i bus i cc wake-up wake-up time high off < 500a v cc /45k resume 3ms low on 1.5ma 50ma resume or remote wake-up 10s the biggest power savings in suspend mode comes when spndpwr is high . in this case, the dc/dc converter is disabled, shutting down power to the isolated side, while the current draw on v cc and v bus are minimized . how- ever, in this mode, if a downstream device is connected or disconnected from the bus or remote wake- up functionality is configured, it will not be recognized by the LTM2884 and will not be relayed to the host . a resume command at the upstream side will wake up the LTM2884 and a re- numeration by the host will be required . recovery time is about 3 ms from the start of the resume command on the upstream side. if spndpwr is low in suspend mode, the LTM2884 oper - ates in a low power mode but maintains a higher functional state with the dc/dc converter on and the downstream transceiver powered. the v bus current is reduced to 1.5ma and v cc current is about 50 ma when there is no external draw on v cc2 . wake-up is initiated with discon- nects, reconnects , or a remote wake-up command from a downstream device or a resume command from the host. recovery time from suspend mode is about 10 s from when the first state change is detected. during suspend mode dc current drawn from v lo into external circuits will be supplied from v bus and may exceed the limits set in the usb specification. dc/dc power supply the internal dc/dc converter converts the input power from the v cc pin to the v cc2 output. the power delivered to the v cc2 pin is regulated and current limited to protect against overcurrent conditions. the voltage supply, v cc , is sensed to limit the maximum current that can be delivered before usb specifications are exceeded. connecting the v cc and v bus supply pins to the usb v bus pin (4.4 v to 5.5v ) lim - its the maximum downstream side supply current to 200ma before v cc2 supply degradation. when v cc is connected to a high voltage external dc source (8.6 v to 16.5 v) the cur- rent limit is increased so that 500 ma is sourced from v cc2 . if a downstream device sinking current from v cc2 draws more than 25 ma, the input current on v cc may exceed 100ma, the usb single unit load specification for low power devices . the LTM2884 does not enforce a 100ma current limit for low power peripherals. v cc2 is internally decoupled to gnd2 with a 22 f capaci- tor. add an additional low esr 100 f capacitor to v cc2 to meet the v bus downstream supply decoupling minimum specification of 120 f when supporting device plug in. locate the additional 100 f capacitor adjacent to the downstream usb connector. additional capacitance may not be necessary when the LTM2884 is used in a peripheral device, or upstream hub application. v lo and v lo2 supplies the v lo and v lo2 output supply pins are available for use as low current 3.3 v supplies on both sides of the isolation barrier. they also serve as supplies for the usb interface circuitry. an internal linear regulator maintains 3.3 v on v lo from the v bus input supply. a separate linear regulator maintains 3.3 v on v lo2 from v cc2 . the current is limited to 10 ma for external applications. exceeding this limit may cause degradation in the v lo or v lo2 supplies and undesirable operation from the usb isolator. connection of signals on or spndpwr to v lo will not cause a significant change in the available v lo current. these supplies are available to support interface logic to the isolated usb port. in order to meet the suspend mode current limit, minimize the dc current of external applications on the v lo output supply. v lo and v lo2 are protected from overcurrent and overtemperature conditions. 2884f for more information www.linear.com/LTM2884 LTM2884
16 a pplica t ions i n f or m a t ion supply current loading the multiple output supply pins of the LTM2884 affects the supply current on v bus and v cc . the v bus input supplies current to the the upstream side of the trans- ceiver and to the v lo pin. the v cc input supplies power to v cc2 and v lo2 through an isolated dc/dc converter. the efficiency ( ) of the dc/dc converter is shown in the typical performance characteristics section for 5 v and 12v inputs from v cc to v cc2 . supply current equations operating: i bus = 6ma + i vlo i cc = v cc2 ? 6ma + i cc2 + i vlo2 ( ) ? v cc suspend: spndpwr = 0 i bus = 1.5ma + i vlo i cc = v cc2 ? 6ma + i cc2 + i vlo2 ( ) ? v cc suspend: spndpwr = v lo i bus = 0.45ma + i vlo i cc = v cc 45k off: i bus = 10a i cc = v cc 45k usb 2.0 compatibility the LTM2884 module transceiver is compatible with the usb 2.0 specification of full and low speed operation. some characteristics and implementations may not support full compliance with the usb 2.0 specification. three specific cases exist within the LTM2884 module transceiver and the integrated dc/dc power converter. first, the propagation delay for full speed data of 80ns exceeds the specification for a single hub of 44 ns plus the attached cable delay of 26 ns. this is due to driving the signal to the 3.3 v rail prior to a k-state transition to maintain balanced crossover voltages equivalent to the cross over voltages of the successive data transitions. usb ports commonly drive the idle state bus to the 3.3v rail prior to the k-state start of packet transition. second, setting spndpwr = v lo will cause the dc/dc power converter to turn off during a bus suspend. v cc2 will lose power causing the downstream device to lose enumeration. remote wake-up, disconnect, and recon- nect events are ignored. a resume command from the host or upstream hub will start the dc/dc converter and wake up the downstream device. the downstream device will require re-enumeration, which causes a failure in usb compliance testing. after a resume command initiates, a delay of 3 ms will elapse before the isolated device is fully powered. when spndpwr = 0 v, the dc/dc power converter remains on during suspend, therefore power and enumeration information is retained. the v cc supply consumes 50 ma to support the isolated power during suspend. separate the v bus and v cc supplies to comply with the 2.5ma usb 2.0 v bus suspend current specification. third, when connecting a low power device to the downstream side of the LTM2884 and v bus and v cc are connected together, the input current is higher due to the operating current and the efficiency of the dc/dc converter. the operating current of the dc/dc converter and the usb transceiver function is 46 ma. the efficiency of the converter is approximately 55%, resulting in a 1/0.55 increase in the input current due to the load current on v cc2 . a 100 ma load on v cc2 appears as a 181 ma load + operating current at v bus and v cc . in order to meet a 100ma input current, the v cc2 load current must be less than 25 ma. this characteristic of an isolated supply may limit the use of the LTM2884 in bus powered hub applica- tions or downstream connection to a bus powered hub. connect v cc to an external supply to mitigate this concern. 2884f for more information www.linear.com/LTM2884 LTM2884
17 a pplica t ions i n f or m a t ion hot plug protection the v cc and v bus inputs are bypassed with low esr ceramic capacitors. during a hot plug event, the supply inputs can overshoot the supplied voltage due to cable inductance. when using external power supply sources greater than 10 v that can be hot plugged, add an ad - ditional 2.2 f tantalum capacitor with greater than 1 of esr, or a ceramic capacitor with a series 1 resistor to the v cc input to reduce the possibility of exceeding absolute maximum ratings. refer to application note 88, ceramic capacitors can cause overvoltage transients, for a detailed discussion of this problem. pc board layout the high integration of the LTM2884 makes pcb layout simple. however, to optimize its electrical isolation char- acteristics, emi, and thermal performance, some layout considerations are necessary. the pcb layout in figure 5 is a recommended configuration for a low emi usb application. the following considerations optimize the performance of the LTM2884: ? under loaded conditions, v cc and gnd current exceed 700ma, v cc2 and gnd2 current is up to 500 ma. use sufficient copper on the pcb to ensure resistive losses do not cause the supply voltage to drop below the minimum allowed level. the heavy copper traces will also help to reduce thermal stress and improve thermal conductivity. ? input and output decoupling is not required on peripheral or hub inputs. add additional low esr capacitance to reduce noise induction on the power supply connec - tions. hub/bus splitter outputs require an additional 100f of low esr capacitance. ? do not place copper between the inner columns of pads on the top or bottom of the pcb. this area must remain open to withstand the rated isolation voltage and maintain the creepage distance. rf, magnetic field immunity the isolator module technology used within the LTM2884 has been independently evaluated, and successfully passed the rf and magnetic field immunity testing requirements per european standard en 55024, 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 t ests were performed using an unshielded test card de - signed per the data sheet pcb layout recommendations. specific limits per test are detailed in t able 2. table 2. test frequency field strength en 61000-4-3, annex d, 80 mhz to 1ghz 1.4 mhz to 2ghz 2ghz to 2.7ghz 10v/m 3v/m 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 emi radiated emissions have been measured for the LTM2884 using a gigahertz transverse electromagnetic ( gtem) cell with and without a usb cable attached. the performance shown in figure 6 was achieved with the layout structure in figure 5. results are corrected per iec 61000-4-20. 2884f for more information www.linear.com/LTM2884 LTM2884
18 a pplica t ions i n f or m a t ion figure 5. pc board layout figure 6. emi plot frequency (mhz) 0 dbv/m 60 50 ?20 40 30 20 10 ?10 ?30 400 200 600 2884 f06 1000 300 100 500 700 900800 0 cispr 22 class b limit detector = peak-hold rbw = 120khz vbw= 300khz sweep time = 680ms # of points = 501 2884 f04 te chn ol ogy dc1789a demo board dc1789a top dc1789a bottom 2884f for more information www.linear.com/LTM2884 LTM2884
19 typical a pplica t ions figure 7. bus powered inline bus splitter figure 8. usb hub upstream isolator 2884 f08 v lo on spndpwr upstream to usb host v cc2 5v v bus v bus gnd v cc isolation barrier LTM2884 d1 + d1 ? v lo2 d2 + d2 ? gnd2 gnd pwr usb hub controller da + da ? db + db ? dc + dc ? 4 usb downstream ports dd + dd ? gnd2 d + d ? 2884 f07 v lo on spndpwr v cc2 v bus2 v bus v bus 100ma or 500ma gnd v cc isolation barrier LTM2884 5v 25ma or 200ma 100f isolated downstream usb port d1 + upstream usb port d1 ? d + d ? v lo2 d2 + d2 ? d + d ? gnd2 gnd2 gnd pwr 2884f for more information www.linear.com/LTM2884 LTM2884
20 typical a pplica t ions figure 9. usb host integration figure 10. powered peripheral device with usb isolation and low current suspend 2884 f09 v lo on spndpwr v cc2 v bus2 v bus gnd v cc 4.4v to 16.5v isolation barrier usb host controller LTM2884 5v up to 200ma for v cc 4.4v to 5.5v 500ma for v cc 8.6v to 16.5v 100f d1 + d1 ? 15k v lo2 d2 + d2 ? d + downstream usb port d ? gnd2 gnd2 pwr 15k 2884 f10 v lo on spndpwr v cc2 v bus v bus gnd v cc isolation barrier LTM2884 d1 + d1 ? d + upstream usb port d ? v lo2 d2 + d2 ? gnd2 gnd pwr peripheral 5v 2884f for more information www.linear.com/LTM2884 LTM2884
21 typical a pplica t ions figure 11. bus or self powered usb isolation with low current suspend and power plug detection 2884 f11 v lo on spndpwr v cc2 v bus gnd v cc isolation barrier LTM2884 d1 + d1 ? d + upstream usb port d ? v lo2 d2 + d2 ? gnd2 gnd pwr peripheral 200ma for v cc 4.4v to 5.5v 500ma for v cc 8.6v to 16.5v v in gnd ctl sense gate stat ltc4412 v in shdn uv ov 4.75k 4.99k 150k gate v out fault gnd ltc4365 overvoltage = 16.7v undervoltage = 8.1v 9v to 16v (500ma) si4230dy-ti-ge3 sia921edj v plug v bus 2884f for more information www.linear.com/LTM2884 LTM2884
22 typical a pplica t ions figure 12. isolated 1w or 2.5w power supply 2884 f12 v lo on spndpwr v cc2 v bus v plug gnd v cc isolation barrier LTM2884 d1 + d1 ? v lo2 d2 + d2 ? gnd2 gnd pwr 200ma for v cc 4.4v to 5.5v 500ma for v cc 8.6v to 16.5v 4.4v to 16.5v (500ma) offon 5v 2884f for more information www.linear.com/LTM2884 LTM2884
23 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. p ackage descrip t ion bga package 44-lead (15mm 15mm 5.02mm) (reference ltc dwg # 05-08-1881 rev a) please refer to http://www .linear.com/designtools/packaging/ for the most recent package drawings. notes: 1. dimensioning and tolerancing per asme y14.5m-1994 2. all dimensions are in millimeters ball designation per jesd ms-028 and jep95 4 3 details of pin #1 identifier are optional, but must be located within the zone indicated. the pin #1 identifier may be either a mold or marked feature package top view 4 pin ?a1? corner x y aaa z aaa z package bottom view 3 see notes suggested pcb layout top view detail a pin 1 0.000 1.270 2.540 2.540 3.810 1.270 0.3175 0.3175 3.810 5.080 6.350 5.080 6.350 6.350 6.350 5.080 5.080 0.000 detail a ?b (44 places) f g h l j k e a b c d 2 1 4 3 567 11 8910 detail b substrate 0.37 ? 0.47 3.95 ? 4.05 // bbb z d a a1 b1 ccc z detail b package side view mold cap z m x yzddd m zeee 0.630 0.025 ? 44x symbol a a1 a2 b b1 d e e f g aaa bbb ccc ddd eee min 4.82 0.50 4.32 0.71 0.60 nom 5.02 0.60 4.42 0.78 0.63 15.0 15.0 1.27 12.70 12.70 max 5.22 0.70 4.52 0.85 0.66 0.15 0.10 0.20 0.30 0.15 notes dimensions total number of balls: 44 e b e e b a2 f g bga 44 1212 rev a tray pin 1 bevel package in tray loading orientation component pin ?a1? module ltmxxxxxx 5. primary datum -z- is seating plane 6. solder ball composition can be 96.5% sn/3.0% ag/0.5% cu or sn pb eutectic 7 package row and column labeling may vary among module products. review each package layout carefully ! 7 see notes 2884f for more information www.linear.com/LTM2884 LTM2884
24 ? linear technology corporation 2014 lt 514 ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/LTM2884 r ela t e d p ar t s typical a pplica t ion part number description comments ltm2881 complete isolated rs485/rs422 module transceiver + power 2500v rms isolation in surface mount bga or lga ltm2882 dual isolated rs232 module transceiver with integrated dc/dc converter 2500v rms isolation in surface mount bga or lga ltm2883 spi or i 2 c module isolator with adjustable 12.5v and 5v regulated power 2500v rms isolation in surface mount bga ltm2892 spi/digital or i 2 c isolated module 3500v rms isolation, 6 channels figure 13. self powered 4-port hub with independent isolation 2884 f13 v bus 12v v lo v cc on spndpwr gnd isolation barrier LTM2884 d4d ? d4d + d3c ? d3c + v lo2 v cc2 v busa gnd2 d2 + d2 ? da + da ? pwr usb port a 100f v bus 12v v lo d2 + d2 ? v cc on spndpwr gnd isolation barrier LTM2884 v lo2 v cc2 v busb gnd2 db + db ? pwr usb port b 100f v bus 12v v lo v cc on spndpwr gnd isolation barrier LTM2884 v lo2 v cc2 v busc gnd2 dc + dc ? pwr usb port c 100f v bus 12v v lo v cc 0.2 51k 1.5k 91k 4.7f 4.7f 0.2 on 15k 27 27 sn74lvc04 spndpwr gnd isolation barrier LTM2884 d1 ? d1 + d1 ? d1 + d2b ? d2b + d1 ? d1 + d1a ? pwron_a pwron_b pwron_c pwron_d d1a + d1 ? d1 + v lo2 v cc2 v busd gndd gndc gndb gnda gnd2 dd + dd ? pwr usb port d 100f status en sd in v s ds gate gnd ltc1154 12v 27 27 3.3v 3.3v 47k 3.3v 15k 15k 27 27 status en sd in v s ds gate gnd ltc1154 6mhz clock signal system power-on reset 12v 15k 0.2 15k 27 27 status en sd in v s ds gate gnd ltc1154 12v 15k 0.2 15k 27 27 status en sd in v s ds gate gnd ltc1154 12v 15k ovrcur4 pwron4 dp4 dm4 dp0 dm0 dp0 v bus dm0 ovrcur3 extmem v cc 12v gnd pwron3 dp3 dm3 xtal1 xtal2 ovrcur2 reset buspwr eedata/ ganged gnd pwron2 dp2 dm2 ovrcur1 pwron1 dp1 dm1 sn75240 max4594 spst gnd no com in v + 3.3v ldo lt1762-3.3 a b c d tusb2046b 3.3v 51k 3.3v 51k 3.3v 51k 3.3v d2 + d2 ? d2 + d2 ? 2884f for more information www.linear.com/LTM2884 LTM2884

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