1 16kv esd protected, +125c, 3.0v to 5.5v, tdfn packaged, low power rs-485/rs-422 transmitter isl3298emrtep the intersil isl3298emrtep is a 16.5kv hbm esd protected (7kv iec61000 contact), 3.0v to 5.5v powered, single transmitter for balanced communication using the rs-485 and rs-422 standards. this driver has very low bus currents (40ma), so it presents less than a ?1/8 unit load? to the rs-485 bus. this allows more than 256 transmitters on the network without violating the rs-485 specificatio n?s 32 unit load maximum, and without using repeaters. hot plug circuitry ensures that th e tx outputs remain in a high impedance state while the power supply stabilizes. the driver on the isl3298emrtep is not limited, so it can achieve a 16mbps data rate and is offered in the -55c to +125c temperature range. this devices also feature a logic supply pin (v l ) that sets the switching points of the de and di inputs to be compatible with a lower supply voltage in mixed voltage systems. for a companion single rs-485 receiver in micro packages, please see the isl32 82emrtep data sheet. applications ?clock distribution ?high node count systems ? space constrained systems ?security camera networks ? building environmental control/lighting systems ? industrial/process control networks features ? specifications per dla vid v62/10602 ? full mil-temp electrical performance from -55c to +125c ? controlled baseline with one wafer fabrication site and one assembly/test site ? full homogeneous lot processing in wafer fab ? no combination of wafer fa brication lots in assembly ? full traceability through assembly and test by date/trace code assignment ? enhanced process change notification ? enhanced obsolescence management ? eliminates need for up-screening a cots component ? high esd protection on rs-485 outputs . . . . 16.5kv hbm - iec61000-4-2 contact test method. . . . . . . . . . . . . . . 7kv - class 3 esd level on all other pins . . . . . . . . . . .>8kv hbm ?specified for +125 c operation (v cc 3.6v only) ? logic supply pin (v l ) eases operation in mixed supply systems ? hot plug - tx output remains three-state during power-up ? low tx leakage allows >256 devices on the bus ? high data rates . . . . . . . . . . . . . . . . . . . . . . . . . up to 16mbps ? low quiescent supply current . . . . . . . . . . . . . . .150 a (max) - very low shutdown supply current . . . . . . . . . . 1 a (max) ? -7v to +12v common mode output voltage range (v cc 3.6v only) ? current limiting and thermal shutdown for driver overload protection (v cc 3.6v only) ? tri-statable tx output ?5v tolerant logic input when v cc 5v table 1. summary of features part number function data rate (mbps) slew-rate limited? hot plug? v l pin? tx enable? maximum quiescent i cc (a) low power shutdown? pin count isl3298emrtep 1 tx 16 no yes yes yes 150 yes 8-tdfn july 28, 2011 fn7607.1 caution: these devices are sensitive to electrostatic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | copyright intersil americas inc. 2010, 2011. all rights reserved intersil (and design) is a trademark owned by intersil corporation or one of its subsidiaries. all other trademarks mentioned are the property of their respective owners.
isl3298emrtep 2 fn7607.1 july 28, 2011 pin configuration isl3298emrtep (8 ld tdfn) top view truth table transmitting inputs outputs de di z y 1101 1010 0xhigh-z *high-z * note: *shutdown mode 2 3 4 1 7 6 5 8 v l de di gnd v cc z y gnd d pin descriptions pin number pin symbol function 1v l logic-level supply which sets the v il /v ih levels for the di and de pins. power-up this supply after v cc , and keep v l v cc. 2 de driver output enable. the driver outputs, y and z, are enabled by bringing de high, and are high impedance when de is low. if the driver enable function isn?t needed, connect de to v cc (or v l ) through a 1k to 3k resistor. 3 di driver input. a low on di forces output y low and output z hi gh. similarly, a high on di forces output y high and output z low. 4, 5 gnd ground connection. this is also the potential of the tdfn thermal pad. 6 y 15kv hbm, 7kv iec61000 (contact method) esd protecte d rs-485/422 level, noninverting transmitter output. 7 z 15kv hbm, 7kv iec61000 (contact method) esd protected rs-485/422 level, inverting transmitter output. 8v cc system power supply input (3.0v to 5.5v). on devices with a v l pin, power-up v cc first. ordering information part number (note) vendor item drawing part marking temp. range (c) package (tape and reel) isl3298emrtep-t v62/10602-01xb 298 -55 to +125 8 ld tdfn ISL3298EMRTEP-TK v62/10602-01xb 298 -55 to +125 8 ld tdfn note: please refer to tb347 for details on reel specifications.
isl3298emrtep 3 fn7607.1 july 28, 2011 typical operating circuit 0.1f + r 5 8 4 1 7 2 v cc gnd ro re b a +3.3v to 5v 0.1f + d 7 6 8 2 3 4, 5 v cc gnd de di z y r t +3.3v isl3282emrtep isl3298emrtep 1 v l 1.8v 6 v l 2.5v v cc logic device (p, asic, uart) v cc logic device (p, asic, uart) network with v l pin for interfacing to lo wer voltage logic devices test circuits and waveforms figure 1a. v od and v oc figure 1b. v od with common mode load figure 1. dc driver test circuits figure 2a. test circuit figure 2b. measurement points figure 2. driver propagation delay and differential transition times d de di v cc or v l v od v oc r l /2 r l /2 z y d de di v cc or v l v od 375 ? 375 ? z y r l = 60 ? v cm -7v to +12v d de di v cc or v l signal generator cd r diff z y out (z) 3v or v l 0v 50% 50% v oh v ol out (y) t sd1 t sd2 diff out (y - z) t r +v od -v od 90% 90% t f 10% 10% di t dsk = |t ddlh - t ddhl | t ssk = |t sd1(y) - t sd2(y) | or |t sd1(z) - t sd2(z) | 50% 50% 50% t ddlh t ddhl 50%
isl3298emrtep 4 fn7607.1 july 28, 2011 figure 3a. test circuit figure 3b. measurement points figure 3. driver enable and disable times figure 4a. test circuit figure 4b. measurement points figure 4. driver data rate test circuits and waveforms (continued) d de di z y v cc gnd sw parameter output di sw t hz y/z 1/0 gnd t lz y/z 0/1 v cc t zh y/z 1/0 gnd t zl y/z 0/1 v cc signal generator 500 ? 50pf out (y, z) 3v or v l 0v 50% 50% v oh 0v v oh - 0.25v t hz out (y, z) v cc v ol v ol + 0.25v t lz de output high output low t zl t zh 50% 50% d de di v cc or v l signal generator z y c d v od + - 54 ? 3v or v l 0v diff out (y - z) +v od -v od di 0v
isl3298emrtep 5 fn7607.1 july 28, 2011 applications information rs-485 and rs-422 are differential (balanced) data transmission standards for use in long haul or noisy environments. rs-422 is a subset of rs-485, so rs-485 transmitters and receivers are al so rs-422 compliant. rs-422 is a point-to-multipoint (multidrop) standard, which allows only one driver and up to 10 (assuming one unit load devices) receivers on each bus. rs-485 is a true multipoint standard, which allows up to 32 one unit load devices (any combination of drivers and receivers) on each bus. to allow for multipoint operation, the rs-485 specification requires that drivers must handle bus contention without sustaining any damage. another important advantage of rs-485 is the extended common mode range (cmr), which specifies that the driver outputs and receiver inputs withstand signals that range from +12v to -7v. rs-422 and rs-485 are intended for runs as long as 4000?, so the wide cmr is necessary to handle ground potential differences, as well as voltages induced in the cable by external fields. driver features this rs-485/rs-422 driver is a di fferential output device that delivers at least 1.5v across a 54 load (rs-485), and at least 2v across a 100 load (rs-422). the drivers feature low propagation delay skew to maximize bit width, and to minimize emi. the driver is tri-statable via the active high de input. if the tx enable function isn?t needed, tie de to v cc (or v l ) through a 1k to 3k resistor. the isl3298emrtep?s output transition times allow data rates of at least 16mbps. wide supply range the isl3298emrtep is optimized for 3.3v operation, but can be operated with supply voltages as high as 5.5v. this device meets the rs-422 and rs-485 specifications for supply voltages less than 4v, and is rs-422 and rs-485 compatible for supplies greater than 4v. operation at +125c requires v cc 3.6v, while 5v operation requires adding output current limiting resistors (as described in the ?driver overload protection? on page 6) if output short circuits (e.g., from bus contention) are a possibility. 5.5v tolerant logic pins logic input pins (di, de) contain no esd nor parasitic diodes to v cc (nor to v l ), so they withstand input voltages exceeding 5.5v regardless of the v cc and v l voltages (see figure 5). logic supply (v l pin) note: power-up v cc before powering up the v l supply. the isl3298emrtep includes a v l pin that powers the logic inputs (di and de). these pins interface with ?logic? devices such as uarts, asics, and controllers, and today most of these devices use power supplies signif icantly lower than 3.3v. thus, the logic device?s low v oh might not exceed the v ih of a 3.3v or 5v powered di or de input. connecting the v l pin to the power supply of the logic device (as sh own in figure 5) reduces the di and de input switching points to values compatible with the logic device?s output levels. tailoring the logic pin input switching points and output levels to the supply voltage of the uart, asic, or controller eliminates the need for a level shifter/translator between the two ics. v l can be anywhere from v cc down to 1.35v, but the input switching points may not prov ide enough noise margin, and 16mbps data rates may not be achievable, when v l <1.5v. the e.c. table in the smd indicates typical v ih and v il values for various v l settings so the user can ascertain whether or not a particular v l voltage meets his/her needs. the v l supply current (i l ) is typically much less than 20a, as shown in figure 9, when de and di are above/below v ih /v il . gnd t xd den v cc = +2v uart/processor gnd di de v cc = +3.3v isl3293e v oh 2v v ih 2v gnd t xd den v cc = +2v uart/processor gnd di de v cc = +3.3v isl3296e v oh 2v v ih = 1.4v v ih = 1.4v v l v oh 2v v ih 2v v oh 2v figure 5. using v l pin to adjust logic levels
isl3298emrtep 6 fn7607.1 july 28, 2011 hot plug function when a piece of equipment powers-up, there is a period of time where the processor or asic driving the rs-485 control line (de) is unable to ensure that the rs- 485 tx outputs are kept disabled. if the equipment is connected to the bus, a driver activating prematurely during power up may crash the bus. to avoid this scenario, the isl3298emrtep incorporates a ?hot plug? function. during power-up, circuitry monitoring v cc ensures that the tx outputs remain disabled for a period of time, regardless of the state of de. this gives the processor/asic a chance to stabilize and drive the rs-485 control lines to the proper states. esd protection all pins on this device incl udes class 3 (8kv) human body model (hbm) esd protection structures, but the rs-485 pins (driver outputs) incorporate advanced structures allowing it to survive esd events in excess of 16.5kv hbm and 7kv to the iec61000 contact test method. the rs-485 pins are particularly vulnerable to esd damage because they typically connect to an exposed port on the exterior of the finished product. simply touching the port pins, or connecting a cable, can cause an esd event that might destroy unprotected ics. these new esd structures protect th e device whether or not it is powered up, and without degrading the rs-485 common mode range of -7v to +12v. this built- in esd protection eliminates the need for board level protection structures (e.g., transient suppression diodes), and the asso ciated, undesirable capacitive load they present. data rate, cables, and terminations rs-485/rs-422 are intended for network lengths up to 4000?, but the maximum system data rate decreases as the transmission length increases. devices operating at 16mbps are limited to lengths less than 100?. twisted pair is the cable of choice for rs-485/rs-422 networks. twisted pair cables tend to pick up noise and other electromagnetically induced voltag es as common mode signals, which are effectively rejected by the differential receivers in these ics. proper termination is imperative, to minimize reflections. in point-to-point, or point-to-multipoint (single driver on bus) networks, the main cable should be terminated in its characteristic impedance (typically 120 ) at the end farthest from the driver. in multi-receiver applications, stubs connecting receivers to the main cable should be kept as short as possible. multipoint (multi-driver) systems require that the main cable be terminated in its characteristic impedance at both ends. stubs connecting a transmitter or receiver to the main cable should be kept as short as possible. driver overload protection as stated previously, the rs-485 specification requires that drivers survive worst case bus contentions undamaged. these drivers meet this requirement, for v cc 3.6v, via driver output short circuit current limits, and on-chip thermal shutdown circuitry. the driver output stages incorpor ate short circuit current limiting circuitry which ensures that the output current never exceeds the rs-485 specification, for v cc 3.6v, even at the common mode voltage range extremes. additionally, these devices utilize a foldback circuit which reduces th e short circuit current, and thus the power dissipation, whenever the contending voltage exceeds either v cc or gnd. in the event of a major short circui t condition, devices also include a thermal shutdown feature that di sables the drivers whenever the die temperature becomes excessive. this eliminates the power dissipation, allowing the die to cool. the drivers automatically re-enable after the die temperature drops about +20c. if the contention persists, the thermal shutdown/re-enable cycle repeats until the fault is cleared. at v cc > 3.6v, the instantaneous short circuit current is high enough that output stage damage may occu r during short circuit conditions to voltages outside of gnd to v cc , before the short circuit limiting and thermal shutdown activate. for v cc = 5v operation, if output short circuits are a possibility (e.g ., due to bus contention), it is recommended that a 5 resistor be inserted in series with each output. this resistor limits the instantaneous current below levels that can cause damage. the driver v od at v cc = 5v is so large that this small added resistance has little impact. high temperature operation due to power dissipation and instantaneous output short circuit current levels at v cc = 5v, these transmitters may not be operated at +125c with v cc > 3.6v. at v cc = 3.6v, the device may be operated at +125c, while driving a 100?, double terminated, cat 5 cable at 16mbps, without triggering the thermal shdn circuit. low power shutdown mode this bicmos transmitter uses a fr action of the power required by its bipolar counterparts and it also includes a shutdown feature that reduces the already low quiescent i cc to a 1a trickle. this device enters shutdown whenever the driver disables (de = gnd).
isl3298emrtep 7 fn7607.1 july 28, 2011 typical performance curves v cc = v l = 3.3v, t a = +25 c ; unless otherwise specified figure 6. driver output current vs differential output voltage figure 7. driver differential output voltage vs temperature figure 8. supply current vs temperature figure 9. v l supply current vs logic pin voltage figure 10. driver output current vs short circuit voltage figure 11. driver differential propagation delay vs temperature differential output voltage (v) driver output current (ma) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 10 20 30 40 50 60 70 80 90 100 110 +25c +85c +125c 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 -55 -35 -15 5 25 45 65 85 105 125 temperature (c) differential output voltage (v) r diff = 100 ? , v l = v cc = 5.0v, l r diff = 100 ? , v l = v cc = 5.0v, h r diff = 54 ? , v l = v cc = 5.0v, l r diff = 54 ? , v l = v cc = 5.0v, h r diff = 100 ? , v l = v cc = 3.3v, l r diff = 100 ? , v l = v cc = 3.3v, h r diff = 54w,v l = v cc = 3.3v, l r diff = 54 ? , v l = v cc = 3.3v, h 95 96 97 98 99 100 101 102 103 104 105 -55 -35 -15 5 25 45 65 85 105 125 temperature (c) i cc (a) v cc = 5.0v, di = h v cc = 5.0v, di = l 024 di voltage (v) i l (a) 135 677.5 v l = 3.3v 0 5 10 15 20 25 30 35 40 v cc = 3.3v v l 2v v l = 2.5v output voltage (v) -7 -6 -4 -2 0 2 4 6 8 10 12 output current (ma) -50 0 50 100 150 200 -100 -150 y or z = low 19 21 23 25 27 29 31 -55 -35 -15 5 25 45 65 85 105 125 temperature (c) propagation delay (ns) v l = v cc 3.3v,skew v l = v cc 3.3v, skew
isl3298emrtep 8 fn7607.1 july 28, 2011 figure 12. driver differential skew vs temperature figure 13. driver si ngle-ended skew vs temperature figure 14. single-ended propagation delay vs temperature figure 15. driver waveforms, high to low die characteristics substrate and tdfn thermal pad potential (powered up): gnd transistor count: 516 process: si gate bicmos typical performance curves v cc = v l = 3.3v, t a = +25 c ; unless otherwise specified (continued) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 -55 -35 -15 5 25 45 65 85 105 125 temperature (c) skew (ns) v l = v cc 3.3v, skew 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 -55 -35 -15 5 25 45 65 85 105 125 temperature (c) skew (ns) y, v l = v cc = 3.3v, skew z, v l = v cc = 3.3v, skew 18 20 22 24 26 28 30 32 -55 -35 -15 5 25 45 65 85 105 125 temperature (c) propagation delay (ns) y, v l = v cc , tddlh z, v l = v cc , tddlh z, v l = v cc = tddhl y, v l = v cc = tddhl time (10ns/div) r diff = 54 ? , c d = 50pf 1.5 3.0 driver output (v) 0 3 driver input (v) di y z 0 -3 -2 -1 0 1 2 3 y - z v l = 1.35v driver output (v)
isl3298emrtep 9 intersil products are manufactured, assembled and tested utilizing iso9000 quality systems as noted in the quality certifications found at www.intersil.com/design/quality intersil products are sold by description only. intersil corporat ion reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnished by intersil is believed to be accurate and reliable. however, no responsi bility is assumed by intersil or its subsid iaries for its use; nor for any infringem ents of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of i ntersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com fn7607.1 july 28, 2011 for additional products, see www.intersil.com/product_tree products intersil corporation is a leader in the design and manufacture of high-performance analog semico nductors. the company's product s address some of the industry's fastest growing markets, such as , flat panel displays, cell phones, handheld products, and noteb ooks. intersil's product families address power management and analog signal processi ng functions. go to www.intersil.com/products for a complete list of intersil product families. *for a complete listing of applications, related documentation an d related parts, please see the respective device information page on intersil.com: isl3298emrtep to report errors or suggestions for this datasheet, please go to www.intersil.com/askourstaff fits are available from our website at http://rel.intersil.com/reports/search.php revision history the revision history provided is for inform ational purposes only and is believed to be accurate, but not warranted. please go t o web to make sure you have the latest rev. date revision change 7/28/11 fn7607.1 changed in features ?specifications per dscc? to ?specifications per dla? to match website. 1/27/11 in figure 8 on page 7, corrected units in y axis from ma to a. 3/30/10 fn7607.0 initial release.
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