NEC Optocouplers for Isolated RS485/RS422 Serial ...
NEC Optocouplers for Isolated RS485/RS422 Serial ...
NEC Optocouplers for Isolated RS485/RS422 Serial ...
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OPTICAL ISOLATION <strong>for</strong> <strong>RS485</strong>/<strong>RS422</strong><strong>NEC</strong> <strong>Optocouplers</strong> <strong>for</strong> <strong>Isolated</strong> <strong>RS485</strong>/<strong>RS422</strong><strong>Serial</strong> Communications Interfaces<strong>NEC</strong> OPTOCOUPLERSThe <strong>RS485</strong> serial communications standardis commonly used in data acquisitionapplications. The standard supports 32drivers and receivers in a 2- or 4-wire differentialconfiguration with cable lengthsup to 4000 feet.Galvanic isolation becomes critical inthe prevention of ground loops, electricalnoise and power spikes in these widelydistributed systems.POWERPWMISOLATION<strong>NEC</strong> OPTOCOUPLERSLMS1487TRANSCEIVERKEY REQUIREMENTSKey requirements <strong>for</strong> optocouplersused <strong>for</strong> isolation in these applicationsinclude:DATA• Wide range of data transfer rates• High Common Mode Rejection(CMR)• Compact size• Repeatability• ReliabilityDIFFERENTIAL BUS TRANSCEIVER ICNational Semiconductor’s LMS1487 is alow power differential bus/line transceiverdesigned <strong>for</strong> high speed bidirectionaldata communication on multipoint bustransmission lines. Designed <strong>for</strong> balancedtransmission lines, it combines aTRI-STATE TM differential line driver anddifferential input receiver, both of whichoperate from a single 5.0V power supply.The LMS1487 is available in an 8 pinSOIC or 8 pin DIP package.APPLICATION NOTE AVAILABLEAn application Note: 2.5Mbps <strong>Isolated</strong><strong>RS485</strong> Communications Interface with upto 500mW Supplementary Power is availableat www.cel.com.RECOMMENDED OPTOCOUPLERS See specifications on next page1 Mbps Analog DevicesPS8101PS8802-1, -2PS8821-1, -210 Mbps Digital DevicesPS9117APS9121PS9821-1, -23750 Vr.m.s breakdown voltage, high CMR, 35V VCC,miniature 5 pin SOP package2500 Vr.m.s breakdown voltage, high CMR, 35V VCC,one or two channel, miniature S08 package2500 Vr.m.s breakdown voltage, high CMR, 7V VCC,one or two channel, miniature S08 packages3750 Vr.m.s. breakdown voltage, high CMR, singlechannel, open collector output, 5 pin SOP package3750 Vr.m.s. breakdown voltage, high CMR, 3.3 V VCC,single channel, 5 pin SOP package2500 Vr.m.s breakdown voltage, high CMR, 3.3 V VCC,one or two channel, miniature S08 packagesData sheets and Application Notes are available at: www.cel.comCL578A 10.22.07
<strong>NEC</strong> OPTOCOUPLERSOPTICAL ISOLATION <strong>for</strong> <strong>RS485</strong>/<strong>RS422</strong>SPECIFICATIONS Data Sheets <strong>for</strong> these devices can be found at www.cel.com<strong>NEC</strong> 1 Mbps Analog <strong>Optocouplers</strong>Absolute Maximum RatingsBV VCC IC tPHL tPLH CTR SafetyPart Number Description (Vr.m.s.) (V) (mA) (ns) (ns) (%) CertificationPS8101High CMR, high breakdown voltage,miniature 5 pin SOP package3750 35 8 0.5 0.6 N = 15 to 35 UL, VDEPS8802-1, -2High CMR, high voltage, one andtwo channel, 8 pin SOP package2500 35 8 0.3 0.6 N = 15 to 35 UL, VDEPS8821-1, -2Low power consumption, one andtwo channel, 8 pin SOP package2500 7 8 0.3 0.5 N = 20 to 40 UL, VDE<strong>NEC</strong> 1 0 Mbps Digital <strong>Optocouplers</strong>Typical PerfomanceVCC IFHL tPHL tPLH BV SafetyPart Number Description (V) (mA) (ns) (ns) (Vr.m.s.) CertificationPS9117AHigh CMR, open collector output,miniature 5 pin SOP package7 2 40 45 3750 UL, VDEPS9121High CMR, low pulse widthdistortion, 5 pin SOP package2.7 – 5.5 2.5 40 45 3750 UL, VDEPS9821-1, -2High CMR, one or two channel,8-pin SOP package2.7 – 5.5 2.5 45 50 2500 UL, VDE Cali<strong>for</strong>nia Eastern Laboratories 4590 Patrick Henry Drive Santa Clara, CA 95054 408.919.2500 info@cel.com www.cel.com
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