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| NM485SLC Low Power Isolated EIA-485 Driver and Receiver ELECTRICAL CHARACTERISTICS Parameter Supply voltage, VCC Isolated reference voltage, VREF +VREF Current High level input voltage, VIH Low level input voltage, VIL Common mode output voltage, VOC High level output current IOH Low level output current, IOL Common mode input voltage, VIC Differential input voltage, VID High level output current, IOH Low level output current, IOL Test conditions Min. 4.75 Typ. 5.0 Max. 5.25 5.0 25 0.8 12 -60 60 12 12 -5.0 25 Units V mA V V V mA mA V V mA mA RL=54 D ENABLE, R ENABLE and DIN 2.8 -7.0 Driver FEATURES RoHS compliant Site compatible with NM485D Single 5V supply Thermal shutdown protection EIA-485 and CCITT V.10 & V.11 compatible Differential driver and receiver Driver tri-state outputs active high enable Low Profile 24 pin DIL package style 1kVrms Isolation Thermal shutdown protection Receiver RECEIVER ELECTRICAL CHARACTERISTICS Parameter High threshold differential input, VTH Low threshold differential input, VTL Input hysteresis, VT High level output voltage, VOH Low level output voltage, VOL Line input current, II Short circuit output current, IOS Input resistance, RI Test conditions VO=2.7V, IO=-0.4mA VO=0.5V, IO=16mA VID=200mV, IOH=-5.0mA VID=-200mV, IOL=25mA Other input at 0V, VI=12V Other input at 0V, VI=-7.0V Min. -0.2 Typ. Max. 0.2 Units V V mV V V mA mA K 70 2.7 0.8 1.0 -0.8 85 12 RECEIVER SWITCHING CHARACTERISTICS DESCRIPTION The NM485SLC is a low power electrically isolated differential driver and receiver designed for bi-directional data communication or multipoint bus transmission at rates up to 2.5Mbits per second. The device combines a tri-state differential line driver and a differential input line receiver. The driver and receiver have active high and active low enables, respectively, which can be connected together to function as direction control. The receiver features a high output state when the inputs are left open. Thermal shutdown protection forces the driver into a high impedance state, under line fault conditions. No external components are needed as a single 5V supply powers all functions either side of the isolation boundary. The device is supplied in a low profile 24 pin plastic package. Parameter Propagation delay time L to H, TPLH Propagation delay time H to L, TPHL Output disable time from high level Output disable time from low level Output enable time to high level Output enable time to low level Test conditions VID=-1.5V to 1.5V, CL=15pF CL=15pF CL=15pF CL=15pF CL=15pF Min. Typ. 150 130 90 90 130 80 Max. 180 150 150 150 150 150 Units ns ns ns ns ns ns RECEIVER FUNCTION TABLE Differential inputs A-B VID0.2V -0.2V Low level Low level Low level High level ROUT High level Undefined Low level High level ISOLATION CHARACTERISTICS Parameter Isolation test voltage Isolation capacitance Conditions Flash tested for 1 second Min. 1000 Typ. 40 Max. Units Vrms pF ABSOLUTE MAXIMUM RATINGS Supply voltage VCC with respect to pin 11 Input voltage D ENABLE, R ENABLE and DIN Receiver differential input voltage range Output voltage range, driver Power dissipation Data transmission rate Lead temperature 1.5mm from case for 10 seconds For full details go to www.murata-ps.com/rohs 7V 7V -14V to +14V -14V to +14V 1000mW 2.5Mbps 300C All data taken at TA=25C, VCC=5V. www.murata-ps.com Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232 KII_NM485SLC.A02 Page 1 of 6 NM485SLC Low Power Isolated EIA-485 Driver and Receiver DRIVER ELECTRICAL CHARACTERISTICS Parameter High level output voltage, VOH Low level output voltage, VOL Differential output voltage, VOD1 Differential output voltage, VOD2 Change in magnitude of differential output voltage, VOD Common mode output voltage, VOC Change in magnitude of common mode output voltage, VOC Output current power off, IO High level input current, IIH Low level input current, IIL Short circuit output current, IOS Test conditions IOH=-25mA IOH=25mA IO=0 RL=100 RL=54 RL=54 or 100 VCC=0, VO=-7.0V to 12V VIH=4.0V VIL=0.8V VO=-7.0V1 VO=12V1 Min. Typ. 3.7 1.1 Max. Units V V V V V V V V A A mA mA mA 1.5 2.0 1.5 -1.0 6.0 5.0 0.2 3.0 0.2 100 20 -15 -250 250 2.0 -8.0 DRIVER SWITCHING CHARACTERISTICS Parameter Differential output delay time, TDD Output disable time from high level, TPHZ Output disable time from low level, TPLZ Propagation delay time L to H, TPLH Propagation delay time H to L, TPHL Differential output transition time, TTD Output enable time to high level, TPZH Output enable time to low level, TPZL Test conditions RL=54, CL=50pF RL=110, CL=50pF RL=110, CL=50pF RL=27, CL=50pF RL=54, CL=50pF RL=110, CL=50pF RL=110, CL=50pF Min. Typ. 20 70 60 80 80 150 80 80 Max. 25 120 120 150 150 300 120 120 Units ns ns ns ns ns ns ns ns DRIVER FUNCTION TABLE DIN High level Low level Irrelevant D ENABLE High level High level Low level DY Output High level Low level High impedance DZ Output Low level High level High impedance TEMPERATURE CHARACTERISTICS Parameter Operating free-air temperature range Storage temperature range Min. 0 -40 Typ. Max. 70 125 Units C C RoHS COMPLIANCE INFORMATION This series is compatible with RoHS soldering systems with a peak wave solder temperature of 300C for 10 seconds. The pin termination finish 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 1. Duration of short circuit should not exceed 1 second. www.murata-ps.com Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232 KII_NM485SLC.A02 Page 2 of 6 NM485SLC Low Power Isolated EIA-485 Driver and Receiver APPLICATION NOTES The increased use of balanced data transmission lines, (distributing data to several system components and peripherals over relatively long lines) has brought about the need for multiple driver/receiver combinations on a single twisted pair line. This resulted in an upgraded version of EIA RS-422, named EIA-485. EIA-485 takes into account EIA RS-422 requirements for balanced line data transmission, and allows for multiple drivers and receivers. The NM485SLC is a low power isolated differential interface providing EIA-485 compatibility. The use of a differential communications interface such as the NM485SLC allows data transmission at high rates and over long distances to be accomplished. This is because effects of external noise sources and cross talk are much less pronounced on the data signal. Any external noise source coupling onto the differential lines will appear as an extra common mode voltage which the receiver is insensitive to. The difference between the signal levels on the two lines will therefore remain the same. Similarly a change in the local ground potential at one end of the line will appear as just another change in the common mode voltage level of the signals. Twisted pair cable is commonly used for differential communications since its twisted nature tends to cause cancellation of the magnetic fields generated by the current flowing through each wire, thus reducing the effective inductance of the pair. Computer and industrial serial interfacing are areas where noise can seriously affect the integrity of data transfer, and a proven route to improve noise performance for any interface system is galvanic isolation. Galvanic isolation removes the ground loop currents from data lines and hence the impressed noise voltage which affects the signal is also eliminated. The isolation feature of the NM485SLC also means that common mode noise effects are removed and many forms of radiated noise are reduced to negligible limits. The NM485SLC has driver thermal shutdown protection which protects the device from line fault conditions. If the outputs of the driver are accidently shorted to a power supply or low impedance source, up to 250mA can flow through the part. The thermal shutdown circuit disables the driver output when the internal temperature of the I.C. reaches 150C and turns it back on when the temperature cools to 130C. If two or more NM485SLCs are used and drivers are shorted directly, the driver outputs can not supply enough current to activate the thermal shutdown. Thus the internal shutdown circuit will not prevent contention faults when two drivers are active on the same bus at the same time. Figure 1 demonstrates how the differential lines of the NM485SLC can be connected to form a transceiver. Data direction is controlled by the driver enable and receiver enable pins. This means the device can receive when the receiver enable is low and transmit when the driver enable is high. As the driver is active high, to reduce the power dissipation even further, it is advisable to disable the driver when not transmitting data. Some data encoding schemes require the output of the receiver to maintain a known state, usually a logic 1, when the data transmission is complete and all drivers are forced into three-state, high impedance. The NM485SLC receiver has a fail safe feature which guarantees the output to be in a logic 1 state when the receiver inputs are left floating (open circuit). However, when the cable is terminated with 120, the differential inputs to the receiver are shorted together, not left floating. Since the receiver has about 70mV hysteresis, the output will maintain the last bit received. Implementing an isolated LONWORKS (TM) network using the NM485SLC The Echleon LONWORKS (Local Operating Network) network is designed to be used in industrial applications in which other electrical 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 NM485SLC is a fully isolated EIA-485 standard driver and receiver, which requires only a single 5V supply. The device offers full data direction programming and can hence be configured as a transceiver. The NM485SLC can be operated at transmitting or receiving data rates of up to 2.5Mbps, hence is fully compatible with the LONTALK (TM) transmission rate standards. Configuring the NM485SLC as a transceiver The NM485SLC is configured as a transceiver simply by connecting the inverting RB receive to the inverting DZ drive and the non-inverting RA receive to the non-inverting DY drive. The data direction is determined by the driver enable pins (D ENABLE and R ENABLE), the transceiver acting as a transmitter when the enable pin is high and a receiver when the enable pin is low. Figure 1 www.murata-ps.com Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232 KII_NM485SLC.A02 Page 3 of 6 NM485SLC Low Power Isolated EIA-485 Driver and Receiver 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 standard specifies a maximum data rate standard of 10Mbps, whereas the maximum LONWORKS data rate standard is 1.25Mbps. The resultant maximum system performance for the LONWORKS EIA-485 configuration is therefore 32 nodes at 1.25Mbps. The NM485SLC isolated serial interface device supports this configuration, as well as any lower specified system. The EIA-485 standard defines the maximum line length as a function of data rate (in Mbps). This implies that the user must choose between the line length of the network and its maximum data transmission rate. The isolated interface has been used in previous configurations (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 primarily to improve noise susceptibility, therefore, unless the line length improvements can be reliably demonstrated by the user, the EIA-485 recommendations on maximum cable length are assumed to apply. The complete hardware implementation for the LONWORKS EIA-485 network is relatively straight forward (see figure 2). 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 loops. Figure 2 Figure 3 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 specified time, across a component designed to provide electrical isolation, to verify the integrity of that isolation. Murata Power Solutions NM485SLC series of DC/DC converters are all 100% production tested at their stated isolation voltage. This 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 specific agency approvals, such as the NM485SLC series, both input and output should normally be maintained 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 an 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; but 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 circuits 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 NM485SLC series has toroidal isolation transformers, with no additional insulation between primary 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 wire insulation. Any material, including this enamel (typically polyurethane) is susceptible to eventual chemical degradation when subject to very high applied voltages thus implying 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 voltage be reduced by 20% from specified 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. www.murata-ps.com Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232 KII_NM485SLC.A02 Page 4 of 6 NM485SLC Low Power Isolated EIA-485 Driver and Receiver PACKAGE SPECIFICATIONS MECHANICAL DIMENSIONS 1.28 (32.60) MAX 0.58 (14.72) NM485SLC XYYWW 0.3 (7.60) MAX 0.1 (2.54) 0.02 (0.002) 0.50 (0.005) 1.1 (27.94) 0.16 (4.10) 0.012 (0.30) 0.008 (0.20) 0.6673 (16.95) MAX Weight: 5.0g All pins on a 0.1 (2.54) pitch. All dimensions are in inches 0.01 (mm 0.25). PIN CONNECTIONS Pin 1 2 3 4 5 6 7-10 11 12-13 14 15 16 17-18 19 20 21-22 23 24 Function ROUT R ENABLE VCC NC D ENABLE DIN NC GND NC VREF NC ISO GND NC DZ DY NC RA RB Description Receiver number output TTL logic Receiver ENABLE (low) +5V supply No Internal Connection Driver ENABLE (High) Driver input TTL logic No Internal Connection Ground No Internal Connection Isolated +5V output No Internal Connection Isolated ground No Internal Connection Driver differential inverting output Driver differential non-inverting output No Internal Connection Receiver differential non-inverting input Receiver differential inverting input RECOMMENDED FOOTPRINT All dimensions are in inches 0.01 (mm 0.25) TUBE OUTLINE DIMENSIONS All dimensions are in inches 0.01 (mm 0.25) Tube Quantity : 15 www.murata-ps.com Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232 KII_NM485SLC.A02 Page 5 of 6 NM485SLC Low Power Isolated EIA-485 Driver and Receiver USA: UK: France: Japan: Tucson (Az), Tel: (800) 547 2537, email: sales@murata-ps.com Milton Keynes, Tel: +44 (0)1908 615232, email: mk@murata-ps.com Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com Tokyo, Tel: 3-3779-1031, email: sales_tokyo@murata-ps.com Osaka, Tel: 6-6354-2025, email: sales_osaka@murata-ps.com Website: www.murata-ps.jp Shanghai, Tel: +86 215 027 3678, email: shanghai@murata-ps.com Guangzhou, Tel: +86 208 221 8066, email: guangzhou@murata-ps.com Canada: Toronto, Tel: (866) 740 1232, email: toronto@murata-ps.com Murata Power Solutions, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A. Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356 www.murata-ps.com email: sales@murata-ps.com ISO 9001 REGISTERED 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 herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. (c) 2008 Murata Power Solutions, Inc. Germany: Munchen, Tel: +49 (0)89-544334-0, email: munich@murata-ps.com China: www.murata-ps.com Technical enquiries - email: mk@murata-ps.com, tel: +44 (0)1908 615232 KII_NM485SLC.A02 Page 6 of 6 |
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