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il3285/il3222 isoloop ? is a registered trademark of nve corporation. *u.s. patent number 5,831, 426; 6,300,617 and others. rev. k nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829- 9217 fax: (952) 829-9189 www.isoloop.com ?nve corporation fractional load rs-485 and rs-422 isolated transceivers functional diagrams r re a b z r re y il3222 il3285 a b v coil2 v coil1 v coil1 v coil2 de d de d il3285 truth table v (a-b) de d r re mode 200 mv h h h l drive ? 200 mv h l l l drive 200 mv l x h l receive ? 200 mv l x l l receive x x x z h x open l x h l receive z = high impedance x = irrelevant il 3222 receiver re r v (a-b) h z x l h 200 mv l l ? 200 mv l h open il3222 driver de d v (y-z) l x z h h 200 mv h l ? 200 mv selection table model full/half duplex no. of devices allowed on bus data rate mbps fail-safe il3285 half 256 5 yes il3222 full 256 5 yes features ? 3.3 v / 5 v input supply compatible ? 5 mbps data rate ? ? unit load ? 15 kv esd protection ? 2500 v rms isolation (1 minute) ? 20 kv/s typical common mode rejection ? 15 kv bus esd protection ? low emc footprint ? ? 40c to +85c temperature range ? thermal shutdown protection ? ul1577 and iec 61010-2001 approved ? 0.15" or 0.3" 16-pin soic packages applications ? high node-count networks ? security networks ? building environmental controls ? industrial control networks ? gaming systems description the il3285 and il3222 are galvanically isolated, differential bus transceivers designed for bidirectional data communication over balanced transmission lines. the devices use nve?s patented* isoloop spintronic giant magnetoresistance (gmr) technology. the il3285 delivers a t least 1.5 v into a 54 ? load, and the il3222 at least 2 v into a 100 ? load, allowing excellent data integrity over long cables. these devices are also compatible with 3.3 v input supplies, allowing interface to standard microcontrollers without additional level shifting. both the il3285 and il3222 have current limiting and thermal shutdown features to protect against output short circuits and bus contentions that may cause excessive power dissipation. the receivers also in corporate a ?fail-safe if open? design, ensuring a logic high on r if the bus lines are disconnected or ?floating.? receiver input re sistance of 96 k? is eight times the rs-485 ?unit load? (ul) minimum of 12 k ? . thus these products are known as ?one-eighth ul? transceivers. there can be up to 256 of these devices on a network while still complying with the rs-485 loading specification. a capacitor (c boost ; see page 7) must be placed across the current limit resistor to ensure the full specified performance.
il3285/il3222 2 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation absolute maximum ratings operating at absolute maximum ratings will not damage the device. however, extended periods of operation at the absolute maximu m ratings may affect performance and reliability. parameters symbol min. typ. max. units test conditions storage temperature t s ? 65 150 c ambient operating temperature t a ? 40 85 c voltage range at a or b bus pins ? 7 12 v supply voltage (1) v dd 1 , v dd 2 ? 0.5 7 v digital input voltage ? 0.5 v dd +0.5 v digital output voltage ? 0.5 v dd +1 v esd protection 15 kv input current i in ? 25 +25 ma esd (all bus nodes) 15 kv hbm recommended operating conditions parameters symbol min. typ. max. units test conditions supply voltage v dd 1 v dd 2 3.0 4.5 5.5 5.5 v ambient operating temperature t a ? 40 85 c input voltage at any bus terminal (separately or common mode) v i v ic 12 ? 7 v input threshold for output logic high i inh 1.5 0.8 ma input threshold for output logic low i inl 5 3.5 ma differential input voltage (2) v id +12/ ? 7 v high-level output current (driver) i oh ? 60 ma high-level digital output current (receiver) i oh ? 8 8 ma low-level output current (driver) i ol ? 60 60 ma low-level digital output current (receiver) i ol ? 8 8 ma ambient operating temperature t a ? 40 85 c digital input signal rise, fall times t ir ,t if 1 s insulation specifications parameters symbol min. typ. max. units test conditions creepage distance (external) 8.08 mm barrier impedance >10 14 ||7 ? || pf leakage current 0.2 a 240 v rms , 60 hz safety approvals iec61010-2001 tuv certificate numbers: n1502812, n1502812-101 classification: reinforced insulation model package pollution degree material group max. working voltage il3222e, il3285e, il3222-3e, IL3285-3E so ic (0.15" and 0.3") ii iii 300 v rms ul 1577 rated 2500 v rms for 1 minute component recognition program file number: e207481 soldering profile per jedec j-std-020c, msl=2 electrostatic discharge sensitivity this product has been tested for electrostatic sensitivity to th e limits stated in the specifica tions. however, nve recommends that all integrated circuits be handled with appropriate care to avoid damage. damage caused by inappropriate handling or storage could range from performance degradation to complete failure.
il3285/il3222 3 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation il3285-3 pin connections (0.15" soic package) 1 v dd1 input power supply 2 gnd 1 ground return for v dd1 3 r output data from bus 4 re read enable (if re is high, r is high impedance) 5 de drive enable 6 v coil1 coils for de and d (connect to v dd1 ) 7 d data input to bus 8 nc no internal connection 9 gnd 2 ground return for v dd2 10 nc no internal connection 11 v dd2 output power supply 12 a non-inverting bus line 13 b inverting bus line 14 nc no internal connection 15 gnd 2 ground return for v dd2 16 v coil2 coil for r (connect to v dd2 ) v dd1 v coil2 gnd 1 v coil1 gnd 2 rn c re b de a d v dd2 nc nc gnd 2 il3285-3 il3222-3 pin connections (0.15" soic package) 1 v dd1 input power supply 2 gnd 1 ground return for v dd1 3 r output data from bus 4 re read enable (if re is high, r is high impedance) 5 de drive enable 6 v coil1 coils for de and d (connect to v dd1 ) 7 d data input to bus 8 nc no internal connection 9 gnd 2 ground return for v dd2 10 y non-inverting driver bus line 11 v dd2 output power supply 12 z inverting driver bus line 13 b inverting receiver bus line 14 a non-inverting receiver bus line 15 gnd 2 ground return for v dd2 16 v coil2 coil for r (connect to v dd2 ) v dd1 v coil2 gnd 1 v coil1 gnd 2 ra re b de z d v dd2 y nc gnd 2 il3222-3
il3285/il3222 4 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation il3285 pin connections (0.3" soic package) 1 v dd1 input power supply 2 gnd 1 ground return for v dd1 3 r output data from bus 4 re read enable (if re is high, r is high impedance) 5 de drive enable 6 v coil1 coils for de and d (connect to v dd1 ) 7 d data input to bus 8 gnd 1 v dd1 ground return for 0.3" package (no internal connection on 0.15" il3285-3) 9 gnd 2 ground return for v dd2 10 nc no internal connection 11 v dd2 output power supply 12 a non-inverting bus line 13 b inverting bus line 14 nc no internal connection 15 gnd 2 ground return for v dd2 16 v coil2 coil for r (connect to v dd2 ) v dd1 v coil2 gnd 1 v coil1 gnd 2 rn c re b de a d v dd2 nc gnd 1 gnd 2 il3285 il3222 pin connections (0.3" soic package) 1 v dd1 input power supply 2 gnd 1 ground return for v dd1 3 r output data from bus 4 re read enable (if re is high, r is high impedance) 5 de drive enable 6 v coil1 coils for de and d (connect to v dd1 ) 7 d data input to bus 8 gnd 1 v dd1 ground return for 0.3" package (no internal connection on 0.15" il3222-3) 9 gnd 2 ground return for v dd2 10 y non-inverting driver bus line 11 v dd2 output power supply 12 z inverting driver bus line 13 b inverting receiver bus line 14 a non-inverting receiver bus line 15 gnd 2 ground return for v dd2 16 v coil2 coil for r (connect to v dd2 ) v dd1 v coil2 gnd 1 v coil1 gnd 2 r a re b de z d v dd2 y gnd 1 gnd 2 il3222
il3285/il3222 5 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation driver section electrical specifications are t min to t max unless otherwise stated. parameters symbol min. typ. max. units test conditions coil input impedance z coil 85||9 ? ||nh t amb = 25c v dd = 3.0 v to 5.5 v temperature coefficient of coil resistance tc r coil 0.2 0.25 ? /c v dd = 3.0 v to 5.5 v output voltage v dd v i o = 0 differential output voltage |v od1 | v dd v i o = 0 differential output voltage |v od2 | 2 3 v r l = 100 ? , v dd = 5 v differential output voltage (6) v od3 1.5 2.3 v r l = 54 ? , v dd = 5 v change in magnitude (7) of differential output voltage |v od | 0.2 v r l = 54 ? or 100 ? common mode output voltage v oc 3 v r l = 54 ? or 100 ? change in magnitude (7) of common mode output voltage |v oc | 0.2 v r l = 54 ? or 100 ? output current (4) 1 ? 0.8 ma ma output disabled, v o = 12 v v o = ? 7 v high level input current i ih 0.8 ma low level input current i il 5 3.5 ma |short-circuit output current| i os 60 250 ma ? 7 v < v o < 12 v supply current (v dd2 = +5 v) (v dd1 = +5 v) i dd2 i dd1 6 2.5 7 3 ma no load (outputs enabled) supply current (v dd1 = +3.3 v) i dd2 1.3 2 ma no load (outputs enabled) switching specifications (v dd1 = +5 v, c boost = 16pf) parameters symbol min. typ. max. units test conditions data rate 5 mbps r l = 54 ? , c l = 50 pf differential output prop delay t d (od) 40 65 ns r l = 54 ? , c l = 50 pf pulse skew (10) t sk (p) 6 20 ns r l = 54 ? , c l = 50 pf differential output rise and fall time t t (od) 3 12 25 ns r l = 54 ? , c l = 50 pf output enable time to high level t pzh 25 80 ns r l = 54 ? , c l = 50 pf output enable time to low level t pzl 25 80 ns r l = 54 ? , c l = 50 pf output disable time from high level t phz 25 80 ns r l = 54 ? , c l = 50 pf output disable time from low level t plz 25 80 ns r l = 54 ? , c l = 50 pf skew limit (3) t sk (lim) 8 ns r l = 54 ? , c l = 50pf common mode rejection |cm h |,|cm l | 15 20 kv/ s v t = 300 v peak switching specifications (v dd1 = +3.3 v, c boost = 16pf) parameters symbol min. typ. max. units test conditions data rate 5 mbps r l = 54 ? , c l = 50 pf differential output prop delay t d (od) 40 65 ns r l = 54 ? , c l = 50 pf pulse skew (10) t sk (p) 6 20 ns r l = 54 ? , c l = 50 pf differential output rise and fall time t t (od) 3 12 25 ns r l = 54 ? , c l = 50 pf output enable time to high level t pzh 25 80 ns r l = 54 ? , c l = 50 pf output enable time to low level t pzl 25 80 ns r l = 54 ? , c l = 50 pf output disable time from high level t phz 25 80 ns r l = 54 ? , c l = 50 pf output disable time from low level t plz 25 80 ns r l = 54 ? , c l = 50 pf skew limit (3) t sk (lim) 8 ns r l = 54 ? , c l = 50pf common mode rejection |cm h |,|cm l | 15 20 kv/ s v t = 300 v peak
il3285/il3222 6 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation receiver section electrical specifications are t min to t max unless otherwise stated. parameters symbol min. typ. max. units test conditions coil input impedance z coil 85||9 ? ||nh t amb = 25c v dd = 3.0 v to 5.5 v temperature coefficient of coil resistance tc r coil 0.2 0.25 ? /c v dd = 3.0 v to 5.5 v positive-going input threshold v it+ 0.2 v ? 7 v < v cm < 12 v negative-going input threshold v it ? ? 0.2 v ? 7 v < v cm < 12 v hysteresis voltage (v it+ ? v it? ) v hys 70 mv v cm = 0v, t = 25c high level digital output voltage v oh v dd ? 0.2 v dd ? 0.2 v v id = 200 mv i oh = 4 ma low level digital output voltage v ol 0.8 v v id = ? 200 mv i ol = 4 ma high impedance state output current i oz 10 a 0.4 v o (v dd2 ? 0.5) v line input current (8) i i 1 ma v i = 12 v ? 0.8 v i = ? 7 v input resistance r i 96 k ? switching characteristics. (v dd1 = +5 v, c boost = 16pf) parameters symbol min. typ. max. units test conditions data rate 5 mbps r l = 54 ? , c l = 50 pf propagation delay (9) t pd 90 150 ns ? 1.5 v o 1.5 v, c l = 15 pf pulse skew (10) t sk (p) 6 20 ns ? 1.5 v o 1.5 v, c l = 15 pf skew limit (3) t sk (lim) 2 8 ns r l = 54 ? , c l = 50 pf output enable time to high level t pzh 4 10 ns c l = 15 pf output enable time to low level t pzl 4 10 ns c l = 15 pf output disable time from high level t phz 4 10 ns c l = 15 pf output disable time from low level t plz 4 10 ns c l = 15 pf switching characteristics. (v dd1 = +3.3 v, c boost = 16pf) parameters symbol min. typ. max. units test conditions data rate 5 mbps r l = 54 ? , c l = 50 pf propagation delay (9) t pd 100 150 ns ? 1.5 v o 1.5 v, c l = 15 pf pulse skew (10) t sk (p) 10 20 ns ? 1.5 v o 1.5 v, c l = 15 pf skew limit (3) t sk (lim) 4 10 ns r l = 54 ? , c l = 50 pf output enable time to high level t pzh 5 10 ns c l = 15 pf output enable time to low level t pzl 5 10 ns c l = 15 pf output disable time from high level t phz 5 10 ns c l = 15 pf output disable time from low level t plz 17 10 ns c l = 15 pf notes (apply to both driver and receiver sections): 1. all voltage values are with respect to network ground except differential i/o bus voltages. 2. differential input/output voltage is m easured at the non-inverting terminal a with respect to the inverting terminal b. 3. skew limit is the maximum difference in any two channels in one device. 4. the power-off measurement in ansi standard eia/tia-422-b app lies to disabled outputs only and is not applied to combined in puts and outputs. 5. all typical values are at v dd1 , v dd2 = 5 v or v dd1 = 3.3 v and t a = 25c. 6. while ?7 v < v cm < 12 v, the minimum v od2 with a 54 ? load is either ? v od1 or 1.5 v, whichever is greater. 7. |v od | and |v oc | are the changes in magnitude of v od and v oc , respectively, that occur when the input is changed from one logic state to the other. 8. this applies for both power on and pow er off; refer to ansi standard rs-485 fo r exact condition. the eia/tia-422-b limit do es not apply for a combined driver and receiver terminal. 9. includes 10 ns read enable time. maximum propagation delay is 25 ns after read assertion. 10. pulse skew is defined as the |t plh ? t phl | of each channel.
il3285/il3222 7 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation 2500 16 5000 3 500 1000 signal rise/fall time (ns) c boost ( pf ) 16 5000 3 1000 signal rise/fall time (ns) c boost ( pf ) 20 50 100 210 power supply decoupling both v dd1 and v dd2 must be bypassed with 47 nf ceramic capacitors. these should be placed as close as possible to v dd pins for proper operation. additionally, v dd2 should be bypassed with a 10 f tantalum capacitor. operation the il3222 and il3285 are current-mode devices. changes in input coil current switch internal spintronic gmr sensors, which then change the logic state of the outputs. the gmr bridge is designed so the output of the isolator is logic high when no field signal is present. a single resistor is required to limit the input coil current to the recommended 5 ma. the absolute maximum current through any coil is 25 ma dc. although logic threshold currents are typically less than the worst-case 5 ma, nve recommends designing for 5 ma logic threshold current in all applications. figure 1 shows the input response of the il3222 and il3285. output logic high is the zero input current state. the output switches to the low state with approximately 3.5 ma of coil current, and back to the high state when the input current falls below approximately 1.5 ma. this allows glitch-free interface with low slew-rate signals. typical resistor values the table shows typical values for the external resistor in 5 v and 3 v logic systems. as always, these values as approximate and should be adjusted for temperature or other application specifics if the expected temperature range is large, 1% tolerance resistors may provide additional design margin. boost capacitor the boost capacitor in parallel with the current-limiting resistor boosts the instantaneous coil current at the signal transition. the boost current pushes the gmr bridge output through the comparator threshold voltage in a bipolar fashion providing important magnetic centering and very reliable switching. select the value of the boost capacitor based on the rise and fall times of the signal driving the inputs. use the chart as a guide to boost capacitor selection. the capacitor value is generally not critical, and can of ten vary 50% with little noticeable difference in device performance provi ded the center value is correct. if in doubt, choose a value higher than indicated, up to a maximum of 470 nf. note however that power dissipation in the input coil increases in proportion to the capacitor value. the correct boost capacitor gives a great deal of design headroom and can usually eliminate design concerns related to temperat ure and power supply fluctuations. 3.5 5 high low logic state coil current ma 1.5 t t figure 1. il3000 series input transfer function v coil 0.125w, 5% resistor 3.3 v 510 5 v 820 figure 2. c boost selector
il3285/il3222 8 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation magnetic field immunity isoloop devices operate by imposing a magnetic field on a gmr sensor, which translates the change in field into a change in log ic state. the devices are manufactured with a magnetic shield above the sensor. the shield acts as a flux concentrator to boost th e magnetic signal from the internal coil, and as a shield agains t external magnetic fields. the shield absorbs surrounding stray flux until it becomes saturated. at saturation the shield is transparen t to external applied fields, and the gmr sensor may react to the field. to compensate for this effect, is oloop isolators use wheatstone bridge structures that ar e only sensitive to differentia l magnetic fields. there are several ways to further enhanced the magnetic field immunity of il3000 transceivers. providing a larger internal field will reduce the effect of an external fiel d on the gmr sensor. immunity to external magnetic fields can a lso be enhanced by proper orientation of the device with resp ect to the field direction and field boosting capacitors. orientation of the device with respect to the field direction an applied field in the ?h1? direction is the worst case for magnetic immunity. in this case the external field is in the same direction as the applied internal field. in one direction it will tend to help switching; in the other it will hinder switching. this can cause unpredictable operation. an applied field in the direction of ?h2? has considerably less effect on the sensor and will result in significantly higher immunity levels as shown in table 1. the greatest magnetic immunity is achieved by adding the current boost capacitor across the input resistor. very high immunity can be achieved with this method. method approximate immuni ty immunity description field applied in direction h1 20 gauss a dc current of 16 a flowing in a conductor 1 cm from the device could cause disturbance field applied in direction h2 70 gauss a dc current of 56 a flowing in a conductor 1 cm from the device could cause disturbance field applied in any direction but with field booster capacitor (470 pf) in circuit 250 gauss a dc current of 200 a flowing in a conductor 1 cm from the device could cause disturbance table 1. magnetic immunity data rate and magnetic field immunity it is easier to disrupt an isolated dc signal with an external magnetic field than it is to disrupt an isolated ac signal. simi larly, a dc magnetic field will have a greater effect on the device than an ac magnetic field of the same effective magnitude. for example, signals with pulses greater than 100 s long are more susceptible to magnetic fields than shorter pulse widths. for input signals faster than 1 mhz, rising in less than 3 ns, a 470 pf field-boost capacitor provides as much as 400 gauss immunity, whi le the same input capacitor might provide just 70 gauss of immunity at 50 khz. figure 3. orientation of external magnetic field v dd1 v coil2 gnd 1 v coil1 gnd 2 r nc re b de a d v dd2 nc gnd 1 gnd 2 h1 h2
il3285/il3222 9 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation applications information rs-485 and rs-422 are differential (balanced) data transmission st andards for use over long distances or in noisy environments. rs-422 is an rs-485 subset, so rs-485 transceivers are also rs-422-compliant. rs-422 is a multi-drop standard allowing only one driver and up to 10 receivers on each bus (assuming unit load receivers). rs-485 is a true mu ltipoint standard which allows up to 32 unit load devices (any combination of drivers and receivers) on each bus. to allow for multipoint operation, rs-485 requi res drivers to handle bus contention without damage. another impor tant advantage of rs-485 is the extended common-mode range (cmr), which requires driv er outputs and receiver i nputs withstand +12 v to ? 7 v. rs-422 and rs-485 are intended for runs as long as 4,000 feet (1,200 m), so the wide cmr is necessary for ground pot ential differences, as well as voltages induced in the cable by external fields. receiver features il3000 transceivers have differen tial input receivers for maximum noise immunity and common-mode rejection. input sensitivity is 200 mv as required by the rs-422 and rs-485 specifications. the receivers include a ?fail-safe if open? function that guarantees a high level receiver output if the receiver inputs ar e unconnected (floating). receivers easily meet the data rates supported by the corresponding driver. il3000- series receiver outputs have tri-state capabilities with active low re inputs. driver features the rs485/422 driver is a differential output device that delivers at least 1.5 v across a 54 ? load (rs-485), and at least 2 v across a 100 load (rs-422). the driver features low propagation delay skew to maximize bit width and minimize emi. il3222 and il3285 drivers have tri-state capability with an active high de input. cabling, data rate and terminations cabling: use twisted-pair cable. the cable can be unshielded if it is shor t (<10 m) and the data rate is slow (<100 kbps). otherwise, us e screened cable with the shield tied to earth ground at one end only. do not tie the shield to digital ground. the other end of the shield may be tied to earth ground through an rc network. this prevents a dc ground loop in the shield. shielded cable minimizes emi emissions and external noise coupling to the bus. data rate: the longer the cable, the slower the data rate. the rs-485 bus can transmit ground over 4,000 feet (1,200 m) or at 10mbps, but not both at the same time. transducer and cable characteristics combine to act as a filter with the general response shown in figure 4. other parameters such as acceptable jitter affect the final cable length versus data rate tradeoff. less jitter means better signal quality but shorter cable lengths or slower data rates. figure 4 shows a generally accepted 30% jitter and a correspondi ng data rate versus cable length. figure 4. cable length vs. data rate (30% jitter). 1000 100 40 4000 100 1k 10k 100k 1m 10m data rate (bps) cable length (feet)
il3285/il3222 10 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation terminations: transmission lines should be terminated to avoid reflections that cause data errors. in rs-485 systems both ends of the bus, no t every node, should be terminated. in rs-422 syst ems only the receiver end should be terminated. 100 ? unterminated parallel proper termination is imperative when using il3285 and il3222 to minimize reflections. unterminated lines are only suitable for very low data rates and very short cable runs, otherwise line re flections cause problems. parallel terminations are the most po pular. they allow high data rates and excellent signal quality. occasionally in noisy environments, fast pul ses or noise appearing on the bus lines cause errors. one way of alleviating such e rrors without adding circuit delays is to place a series resistor in the bus line. dependi ng on the power supply, the resistor should be between 300 ? (3 v supply) and 500 ? (5 v supply). typical coil connections r re a b v dd2 v coil2 v coil1 v dd1 de d r1 16pf 50% 16pf 50% 16pf 50% r2 r3 a b z r re y v coil2 v dd2 v coil1 v dd1 de d r1 r2 r3 16pf 50% 16pf 50% 16pf 50% v dd1 = v dd2 = 5 v r1, r2, r3 = 820 ? v dd1 = 3.3 v r1, r2 = 510 ? ; ? r3 = 820 ? v dd1 = v dd2 = 5 v r1, r2, r3 = 820 ? v dd1 = 3.3 v r1, r2 = 510 ? ; ? r3 = 820 ?
il3285/il3222 11 nve corporation 11409 valley view road, eden prairie, mn 55344-3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?2008 nve corporation fail-safe operation: ?fail-safe operation? is defined here as the forcing of a logic high state on the ?r? output in response to an open-circuit con dition between the ?a? and ?b? lines of the bus, or when no drivers are active on the bus. proper biasing can ensure fail-safe operation, that is a know n state when there are no active drivers on the bus. il3285 and il 3222 isolated transceivers include internal pull-up and pull-down resistors of approximately 200 k ? in the receiver section (r fs-int ; see figure below). these internal resistors are designed to ensure failsafe operation but only if there are no termination resistor s. the entire v dd will appear between inputs ?a? and ?b? if there is no loading and no termination re sistors, and there will be more than the required 200 mv with up to four rs-485/rs-422 worst-case one-eighth unit loads of 96 k ? . many designs operating below 1 mbps or less than 1,000 feet are untermina ted. termination resistors may not be nece ssary for very low da ta rates and very sh ort cable runs because reflections have time to settle before data sampling, which occurs at th e middle of the bit interval. in busses with low-impedance termination resistors, however, the differential voltage across the conductor pair will be close t o zero with no active drivers. in this case the state of the bus is indeterminate, and the idle bus will be susceptible to noise. for example, with 120 ? termination resistors (r t ) on each end of the cable, and four eighth unit loads (96 k ? each), without external fail-safe biasing resistors the internal pull-up and pull-down resistors will produce a voltage between inputs ?a? and ?b? of o nly about one millivolt. this is not nearly enough to ensure a known state. external fa il-safe biasing resistors (r fs-ext ) at one end of the bus can ensure fail-safe operation with a terminated bus. re sistors should be selected so that under worst-case power suppl y and resistor tolerances there is at least 200 mv across the c onductor pair with no active driver s to meet the input sensitivity specification of the rs-422 and rs-485 standards. using the same value for pull-up and pull-down biasing resistors maintains balance for positive- and negative going transitions . lower-value resistors increase inactive noise immunity at the expense of quiescent power consumption. note that each unit load on the bus adds a worst-case loading of 12 k ? across the conductor pair, and 256 one-eighth unit loads add 375 ? worst-case loading. the more loads on the bus, the lower the required values of the biasing resistors. in the example with two 120 ? termination resistors and four eighth unit loads, 560 ? external biasing resistors provide more than 200 mv between ?a? and ?b? with adequate margin for power supply variations and resistor tolerances. this ensures a known state when there are no active drivers. other illustrative examples are shown in the table below. fail-safe biasing r b v dd 200k gnd a 5 v r fs-ext r t r t r fs-ext r fs-int r fs-int 200k il32xx fail-safe r t loadin g operation? none four eighth- unit loads (96 k ? ea.) 283 mv yes 120 ? four eighth- unit loads (96 k ? ea.) 1 mv no 560 ? 120 ? four eighth- unit loads (96 k ? ea.) 254 mv yes 510 ? 120 ? 256 eighth-unit loads (96 k ? ea.) 243 mv yes nominal v a-b (inactive) r fs -ext internal only internal only
il3285/il3222 12 nve corporation 11409 valley view road, eden prairie, mn 55344 -3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?nve corporation package drawings, dimensions and specifications 0.15" 16-pin soic 0.054 (1.4) 0.072 (1.8) 0.040 (1.0) 0.060 (1.5) 0.016 (0.4) 0.050 (1.3) 0.386 (9.8) 0.394 (10.0) pin 1 identified by either an indent or a marked dot nom 0.228 (5.8) 0.244 (6.2) 0.152 (3.86) 0.157 (3.99) dimensions in inches (mm) 0.007 (0.2) 0.013 (0.3) 0.004 (0.1) 0.012 (0.3) 0.040 (1.02) 0.050 (1.27) 0.013 (0.3) 0.020 (0.5) pin spacing is a basic dimension; tolerances do not accumulate note: 0.3" 16-pin soic nom pin 1 identified by either an indent or a marked dot 0.287 (7.29) 0.300 (7.62) dimensions in inches (mm) 0.08 (2.0) 0.10 (2.5) 0.092 (2.34) 0.105 (2.67) 0.397 (10.1) 0.413 (10.5) 0.013 (0.3) 0.020 (0.5) 0.394 (10.00) 0.419 (10.64) 0.040 (1.0) 0.060 (1.5) 0.004 (0.1) 0.012 (0.3) 0.007 (0.2) 0.013 (0.3) 0.016 (0.4) 0.050 (1.3) pin spacing is a basic dimension; tolerances do not accumulate note:
il3285/il3222 13 nve corporation 11409 valley view road, eden prairie, mn 55344 -3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?nve corporation ordering information and valid part numbers il 32 85 -3 e tr13 bulk packaging blank = tube tr13 = 13'' tape and reel package e = rohs compliant package type blank = 0.3'' soic -3 = 0.15'' soic channel configuration 22 = rs-422 85 = rs-485 base part number 32 = passive-in, 1/8-load transceiver product family il = isolators valid part numbers il3285e il3285e tr13 IL3285-3E IL3285-3E tr13 il3222e il3222e tr13 il3222-3e il3222-3e tr13 rohs compliant
il3285/il3222 14 nve corporation 11409 valley view road, eden prairie, mn 55344 -3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?nve corporation revision history isb-ds-001-il3185/22-k august 2009 changes ? changes to current-limiting resistor values (pp. 7 and 10). ? details for boost capacitor selection (p. 7). isb-ds-001-il3285/22-j change ? noted ul1577 approval. isb-ds-001-il3285/22-i change ? added bus-protection esd specification (15 kv). isb-ds-001-il3285/22-h changes ? added typical coil resistance and temp erature coefficient specifications. ? added note on package drawings that pi n-spacing tolerances are non-accumulating. isb-ds-001-il3285/22-g changes ? changed ordering information to reflect that devices are now fully rohs compliant with no exemptions. isb-ds-001-il3285/22-f changes ? eliminated soldering profile chart isb-ds-001-il3285/22-e changes ? separate pinout diagrams for narrow- and wide-body packages isb-ds-001-il3285/22-d changes ? added ?open ? input condition to truth tables ? fail-safe biasing section added ? narrow-body soic packages added isb-ds-001-il3285/22-c changes 1. capacitor information added on page 1 2. input signal rise/fall times changed from 10 s to 1 s 3. typical coil formations show c boost 4. switching characteristics show c boost = 16 pf isb-ds-001-il3285/22-b revision a not released isb-ds-001-il3285/22-a internal release only
il3285/il3222 15 nve corporation 11409 valley view road, eden prairie, mn 55344 -3617 phone: (952) 829-9217 fax: (952) 829-9189 www.isoloop.com ?nve corporation about nve an iso 9001 certified company nve corporation manufactures innovative products based on uni que spintronic giant magnetoresistive (gmr) technology. products include magnetic field sensors, magnetic field gradient sensors (gradiometers), digital magnetic field sensors, digita l signal isolators, and isolated bus transceivers. nve pioneered spintronics and in 1994 introduced the world?s first products using gmr material, a line of ultra-precise magneti c sensors for position, magnetic media, gear speed and current sensing. nve corporation 11409 valley view road eden prairie, mn 55344-3617 usa telephone: (952) 829-9217 fax: (952) 829-9189 internet: www.nve.com e-mail: isoinfo@nve.com the information provided by nve corpor ation is believed to be accurate. however, no responsibility is assumed by nve corporation for its use, nor for any infringement of patents, nor rights or licenses granted to third parties, which may result from its use. no license is granted by implication, or otherwise, unde r any patent or patent rights of nve corporation. nve corporation does not authorize, nor warrant, any nve co rporation product for use in life support devices or systems or other critical applications, without the express written approval of the president of nve corporation. specifications are subject to change without notice. isb-ds-001-il3285/22-k august 2009

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