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technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 1 of 7 www.murata-ps.com for full details go to www.murata-ps.com/rohs $ www.murata-ps.com electrical characteristics parameter test conditions min. typ. max. units supply voltage, v cc 4.75 5.0 5.25 v high level input voltage, v ih d x enable and d inputs 2.8 v low level input voltage, v il 0.8 v common mode output voltage, v oc driver -7.0 12 v high level output current i oh -60 ma low level output current, i ol 60 ma common mode input voltage, v ic receiver 12 v differential input voltage, v id 12 v high level output current, i oh -5.0 ma low level output current, i ol 25 ma each receiver electrical characteristics parameter test conditions min. typ. max. units high threshold differential input, v th v o =2.7v, i o =-0.4ma 0.2 v low threshold differential input, v tl v o =0.5v, i o =16ma -0.2 v input hysteresis, v t 50 mv high level output voltage, v oh v id =200mv, i oh =-5.0ma 2.7 v low level output voltage, v ol v id =200mv, i ol =25ma 0.8 v line input current, i i other input at 0v, v i =12v 1.0 ma other input at 0v, v i =-12v -0.8 ma short circuit output current, i os -15 ma input resistance, r i 12 k receiver switching characteristics parameter test conditions min. typ. max. units propagation delay time l to h, t plh v id =-1.5v to 1.5v, c l =15pf 70 155 ns propagation delay time h to l, t phl 72 135 ns receiver function table differential inputs a-b rx out v id 0.2v high level -0.2vNM485Dc is an electrically isolated dual differential driver and receiver designed for bal- anced mulipoint bus transmission at rates up to 1.25mbits per second. the device provides two receive channels and two driver channels. the two driver channels have an active high enable. no external components are needed and a single 5v input supply powers all functions either side of the isolation boundary. the driver outputs provide limiting for positive and negative currents and thermal shutdown protection from line fault condi- tions on the transmission bus line. the receiver outputs will always be high if the receiver inputs are open. the isolation voltage between input and output is 1000vrms, the devices are supplied in a low pro? le 24 pin dil plastic package.
technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 2 of 7 www.murata-ps.com each driver electrical characteristics parameter test conditions min. typ. max. units high level output voltage, v oh i oh =-33ma 3.7 v low level output voltage, v ol i oh =33ma 1.1 v differential output voltage, v od1 i o =0 1.5 6.0 v differential output voltage, v od2 r l =100 2.0 v r l =54 1.5 5.0 v change in magnitude of differential output voltage, v od r l =54 or 100 0.2 v common mode output voltage, v oc -1.0 3.0 v change in magnitude of common mode output voltage, v oc 0.2 v output current power off, i o v cc =0, v o =-7.0v to 12v 100 a high level input current, i ih v ih =4.0v 2.0 20 a low level input current, i il v il =0.8v -15 ma short circuit output current, i os v o =-7.0v 1 -250 ma v o =12v 1 250 ma driver switching characteristics parameter test conditions min. typ. max. units differential output delay time, t dd r l =54, cl=50pf 20 25 ns output disable time from high level, t phz r l =110, cl=50pf 90 120 ns output disable time from low level, t plz r l =110, cl=50pf 30 45 ns propagation delay time l to h, t plh r l =27, cl=50pf 70 145 ns propagation delay time h to l, t phl 70 145 ns differential output transition time, t td r l =54, cl=50pf 150 300 ns output enable time to high level, t pzh r l =110, cl=50pf 80 120 ns output enable time to low level, t pzl r l =110, cl=50pf 40 60 ns driver function table dx in d x enable dx y output dx z output high level high level high level low level low level high level low level high level irrelevant low level high impedance high impedance temperature characteristics parameter min. typ. max. units operating free-air temperature range 060oc storage temperature range -40 125 oc 1. duration of short circuit should not exceed 1 second.
technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 3 of 7 www.murata-ps.com application notes the eia-485 standard is an upgrade version of the eia rs-422 standard. the use of balanced data transmission lines in distribut ing data to several systems components and peripherals over relatively long lines, requires the use of multiple driver/receiver combinations on a single twisted pair line. this is referred to as a party-line (see ? gure 1). the NM485Dc is an isolated interface device providing eia-485 compatibility. a single supply provides all necessary power for t he device, either side of the isolation bound- ary. the isolation feature allows the logic and differential grounds to be isolated from each other, eliminating ground loop cu rrent and inherently long noise paths. the maximum number of drivers and receivers that may be placed on a single communication bus depends upon their loading charact eristics, relative to the de? nition of a unit load (u.l.), transmission speed does not affect the unit load capability. as the NM485Dc complies with the eia-485 stand ard a maximum of 32 unit loads per line is recommended. a unit load usually consists of a driver-receiver pair, but not the line termination resistors. with only a 5v supply connected, the NM485Dc receiver and differential outputs give levels greater than +2.7v and 1.5v respect ively. this known output state may be used as a reference for use in environments with considerable levels of noise. an unused driver should be disabled by grounding its enable pin to reduce power dissipation. figure 2 illustrates the way one receiver and one driver of the NM485Dc may be connected to implement an isolated eia-485 inter face with a typical uart and processor bus. figure 3 demonstrates how the NM485Dc may be used as a transceiver. this is possible by using the driver enable to determi ne the data direction. for example, the device could receive when the driver enable is low and transmit when it is high. precise circuitry will depend on the application and in particular the use of the control lines shown will need to be altered t o suit the situation. for instance the maximum sychronous baud rate of the 8251a is 64kbps, whereas the NM485Dc had a maximum baud rate of 1.25mbps. implementing an isolated lonworks ( ? ) network using the NM485Dc the echleon lonworks (local operating network) network is designed to be used in industrial applications in which other eletrical equipment is operated. often the lon (r) will be the method of controlling machinery or sensing machine activity. the environment is therefore likely to be electrically noisy and to reduce the possibility of data corruption, an isolated network communications system is a preferred method of data transfer. the eia-485 standard provides a method of achieving multi- point (multi-drop) data transmission over balanced twisted pair transmission lines. the standard is a differential scheme offering a large degree of common mode immunity compared to single ended schemes. the isolated differential method offers the highest common mode and line noise immunity for wire based systems. the NM485Dc is a fully isolated eia-485 standard dual driver and receiver, which requires only a single 5v supply. the device offers full data direction programming and can hence be con? gured as a transceiver. the NM485Dc can be operated at transmitting or receiving data rates of up to 1.25mbps, hence is fully compatible with the lontalk ( ? ) transmission rate standards. con? guring the NM485D as a transceiver the NM485D is con? gured as a transceiver simply by con- necting the inverting r1 b receive to the inverting d1 z drive and the non-inverting r1 a receive to the non-inverting d1 y drive, similarly r2 b to d2 z and r2 a to d2 y for the second transceiver (see ? gure 3), in this way the NM485D is con? gured as a dual transceiver. the data direction is determined by the driver en- able pins (d x enable), the transceiver acting as a transmitter when the enable pin is high and a receiver when the enable pin is low. if only a single transceiver is required it is recommended that the second transceiver driver is disabled, this reduces the power consumption to around 0.6w. the second driver is disabled by taking the driver enable pin low, this should be via a pull-down resistor (recommend value is 1k). 35 35 3fdfjwfs 3fdfjwfs %sjwfs %sjwfs $pnnpo*tpmbufe (spvoe-jof %"5"5&3.*/"- " /.% ,&:#0"3% %*41-": 1spdfttps #vt 3 9 % 5 9 3%: 5 9 3 065 % &/"#-& % */ 3fdfjwfs %sjwfs 3 # 3 " % : % ; ? ? %"5"5&3.*/"- " /.% *tpmbujpo#bssjfs 1spdfttps #vt 3 9 % 5 9 3%: 5 9 3 065 7 $$ (/% % &/"#-& % */ 3 # 3 " % : % ; *40(/% &*" figure 1 figure 2 figure 3
technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 4 of 7 www.murata-ps.com application notes (continued) system performance the eia-485 standard allows a maximum of 32 unit loads to be connected to the network, this is less than the lonworks standard of 64 nodes. a unit load is any single driver, receiver or transceiver in the eia-485 standard, or any single node under the lonworks scheme. similarly the eia-485 st andard speci? es a maximum data rate standard of 10mbps, whereas the maximum lonworks data rate standard is 1.25mbps. the resultant maximum system performance for t he lonworks eia-485 con- ? guration is therefore 32 nodes at 1.25mbps. the NM485D isolated serial interface devices supports this con? guration, as well as any lower speci? ed system. the eia-485 standard de? nes the maximum line length as a function of data rate (in mbps). this implies that the user must choo se between the line length of the network and its maximum data transmission rate. the isolated interface has been used in previous con? gurations (e.g. nm232d) to increase the available line length as isolated data lines are much less susceptible to ground currents and variations in local supplies. the feature of isolation in a lon environment is intended to be used primaril y to improve noise susceptibility, therefore, unless the line length improvements can be reliably demonstrated by the user, the eia-485 recommendations on maximum cable leng th are assumed to apply. the complete hardware implementation for the lonworks eia-485 network is relatively simple and straight forward (see ? gure 5). there is a minimum of components required, only 1 interface part and one resistor, and the complete lontalk transmission protocols are supported. the isolation barrier of 1000vrms offers improved noise immunity compared to a non-isolated system and eliminates node-to-node supply voltage mismatch and possible ground current loop s. if protection from voltage transients is required, then a bi-directional transzorb from each line side to ground should be conn ected (see ? gure 6). a transzorb with a breakdown voltage higher than the common-mode voltage required should be used. however the added parasitic capacitance will loa d down the bus, and should therefore be taken into consideration. figure 5 /&630/ /.% $139 $15& $159 3 065 7 $$ (/% % &/"#-& % */ 3 # 3 " % : % ; *40(/% 3fdfjwfs ? ? &*"/&5803, 7 7 ,? $1 %sjwfs figure 4 %bubsbuf $bcmfmfohui nfusft
.byjnvn#bve3buf %bub4jhobmmjoh3buf cjuttfdpoe %sjwfs ? figure 6
technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 5 of 7 www.murata-ps.com application notes (continued) NM485D receiver output status the receiver output will be high (>2.7v) when the differential input lines are left open (open circuit). however, when a line t ermination resistor is attached, the inputs are effectively shorted together, not left ? oating. since the receiver has typically 70mv of hysteresis, the output will remain in its last active state, high or low. to force the receiver output to a known state, the con? guration shown in ? gure 7 should be used. it should be noted that this arrangement will use typically 100mw of power, for each receiver connected in this manner. the termination resistors are used to generate a dc bias, which forces the receiver into a high state, when no signal is applie d. this arrangement will still allow the output to switch due to a change at the input, whilst maintaining line termination characteristics. technical notes isolation voltage hi pot test, flash tested, withstand voltage, proof voltage, dielectric withstand voltage & isolation test voltage are all terms that relate to the same thing, a test voltage, applied for a speci? ed time, across a component designed to provide electrical isolation, to verify the integrity of that isol ation. murata power solutions NM485Dc series of dc/dc converters are all 100% production tested at their stated isolation voltage. thi s is 1000vrms for 1 second. a question commonly asked is, what is the continuous voltage that can be applied across the part in normal operation? for a part holding no speci? c agency approvals, such as the NM485Dc series, both input and output should normally be maintaine d within selv limits i.e. less than 42.4v peak, or 60vdc. the isolation test voltage represents a measure of immunity to transient voltages and the part should never be used as a n element of a safety isolation system. the part could be expected to function correctly with several hundred volts offset applied continuously across the isolation barrier; bu t then the circuitry on both sides of the barrier must be regarded as operating at an unsafe voltage and further isolation/insulation systems must form a barrier between these circui ts and any user-accessible circuitry according to safety standard requirements. repeated high-voltage isolation testing it is well known that repeated high-voltage isolation testing of a barrier component can actually degrade isolation capability, to a lesser or greater degree depending on materials, construction and environment. the NM485Dc series has toroidal isolation transformers, with no additional insulation between pri mary and secondary windings of enameled wire. while parts can be expected to withstand several times the stated test voltage, the isolation capability does depend on the w ire insulation. any material, including this enamel (typically polyurethane) is susceptible to eventual chemical degradation when subject to very high applied voltages thus implyi ng that the number of tests should be strictly limited. we therefore strongly advise against repeated high voltage isolation testing, but if it is absolutely required, that the voltag e be reduced by 20% from speci? ed test voltage. this consideration equally applies to agency recognized parts rated for better than functional isolation where the wire enamel insulation is always supplemented by a further insulation system of physical spacing or barriers. rohs compliance information this series is compatible with rohs soldering systems with a peak wave solder temperature of 300oc for 10 seconds. the pin term ination ? nish on this product series is matte tin over nickel preplate. the series is backward compatible with sn/pb soldering systems . for further information, please visit www.murata-ps.com/rohs , 3 , 7 07 3 " 3 # 3 065
technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 6 of 7 www.murata-ps.com package specifications mechanical dimensions pin connections recommended footprint pin function description 1r1 out receiver number 1 output ttl logic 2 nc no internal connection 3v cc +5v supply 4r2 out receiver number 2 output ttl logic 5d 1 enable driver no.1 enable 6d1 in driver no.1 input ttl logic 7 nc no internal connection 8d 2 enable driver number 2 enable 9d2 in driver number 2 input ttl logic 10 nc no internal connection 11 gnd ground 12-15 nc no internal connection tube outline dimensions 16 iso gnd isolated ground 17 d2 y driver number 2 differential non-inverting output 18 d2 z driver number 2 differential inverting output 19 d1 z driver number 1 differential inverting output 20 d1 y driver number 1 differential non-inverting output 21 r2 b receiver number 2 differential inverting input 22 r2 a receiver number 2 differential non-inverting input 23 r1 a receiver number 1 differential non-inverting input 24 r1 b receiver number 1 differential inverting input 1.28 (32.60) max 0.58 (14.72) 0.3 (7.60) max 0.1 (2.54) 0.6673 (16.95) max 0.012 (0.30) 0.008 (0.20) 0.16 (4.10) 0.02 (0.002) 0.50 (0.005) 1.1 (27.94) NM485Dc xyyww ? ?
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? weight: 5.9g all pins on a 0.1 (2.54) pitch. all dimensions are in inches (mm) 0.01 (0.25). all dimensions are in inches (mm) 0.01 (0.25) tube quantity : 15 all dimensions are in inches (mm) 0.01 (0.25)
technical enquiries email: mk@murata-ps.com, tel: +44 (0)1908 615232 NM485Dc series isolated dual eia-485 driver and receiver 2009-12-09 kii_NM485Dc.a03 page 7 of 7 murata power solutions, inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. the descriptions contained her ein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. speci? cations are subject to cha nge without notice. ? 2009 murata power solutions, inc. murata power solutions, inc. 11 cabot boulevard, mans? eld, ma 02048-1151 u.s.a. iso 9001 and 14001 registered www.murata-ps.com/locations

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