Manual de instrucciones de National DS36C278

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DS36C278 Low Power Multipoint EIA-RS-485 Transceiver
December 1995
DS36C278
Low Power Multipoint EIA-RS-485 Transceiver
General Description Features
Y
100% RS-485 compliant
The DS36C278 is a low power differential bus/line trans-
Ð Guaranteed RS-485 device interoperation
ceiver designed to meet the requirements of RS-485 stan-
Y
dard for multipoint data transmission. In addition it is com- Low power CMOS design I 500 mA max
CC
patible with TIA/EIA-422-B. Y
Built-in power up/down glitch-free circ

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Absolute Maximum Ratings (Note 1) Recommended Operating If Military/Aerospace specified devices are required, Conditions please contact the National Semiconductor Sales Min Typ Max Units Office/Distributors for availability and specifications. a a a Supply Voltage (V ) 4.75 5.0 5.25 V CC Supply Voltage (V ) a12V CC Bus Voltage b7 a12 V b a Input Voltage (DE, RE*, & DI) 0.5V to (V 0.5V) CC Operating Free Air Temperature (Ta) Common Mode (V ) DS36C278T b40 25 a85 C CM § a Driver Output/Receiver In

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Electrical Characteristics (Continued) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 2 and 3) Symbol Parameter Conditions Reference Min Typ Max Units e ea I Line Input Current Other Input 0V, DS36C278 V 12V 0 0.19 0.25 mA IN IN (Note 7) DE e V ,RE*eV , IL IL eb b b V 7V 0 0.1 0.2 mA IN e V 4.75 to 5.25 CC DS36C278T ea V 12V 0 0.19 0.5 mA IN or 0V eb b b V 7V 0 0.1 0.4 mA IN e ea I Line Input Current Glitch Other Input 0V, DS36C278 V 12V 0 0.19 0.25 mA IN

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Switching Characteristics (Continued) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified (Notes 3 and 8) Symbol Parameter Conditions Reference Min Typ Max Units RECEIVER CHARACTERISTICS t Propagation Delay C e 15 pF PHL L 30 210 400 ns High to Low Figures 12, 13 t Propagation Delay PLH 30 190 400 ns Low to High b t Skew, t t 020 50 ns SK l PHL PLHl e t Output Disable Time C 15 pF Ð 50 150 ns PLZ L t Ð 55 150 ns PHZ Figures 14, 15, 16 t Output Enable Time Ð 40 150 ns

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Parameter Measurement Information (Continued) TL/F/12040±6 FIGURE 6. Driver Differential Propagation Delays and Differential Rise and Fall Times TL/F/12040±8 FIGURE 8. TRI-STATE Waveforms (t ,t ) PZH PHZ TL/F/12040±7 FIGURE 7. TRI-STATE Test Circuit (t ,t ) PZH PHZ TL/F/12040±10 FIGURE 10. TRI-STATE Waveforms (t ,t ) PZL PLZ TL/F/12040±9 FIGURE 9. TRI-STATE Test Circuit (t ,t ) PZL PLZ TL/F/12040±12 FIGURE 12. Receiver Differential Propagation Delay TL/F/12040±11 Test Circuit FIGURE 11. Receiver

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Parameter Measurement Information (Continued) TL/F/12040±13 FIGURE 13. Receiver Differential Propagation Delay Waveforms TL/F/12040±14 FIGURE 14. Receiver TRI-STATE Test Circuit TL/F/12040±15 FIGURE 15. Receiver Enable and Disable Waveforms (t ,t ) PLZ PZL TL/F/12040±16 FIGURE 16. Receiver Enable and Disable Waveforms (t ,t ) PHZ PZH http://www.national.com 6

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Typical Application Information TL/F/12040±17 FIGURE 17. Typical RS-485 Bus Interface TABLE I. Device Pin Descriptions Pin No. Name Description t 1 RO Receiver Output: When RE (Receiver Enable) is LOW, the receiver is enabled (ON), if DO/RI DO*/RI* by s 200 mV, RO will be HIGH. If DO/RI DO*/RI* by 200 mV, RO will be LOW. Additionally RO will be HIGH for OPEN (Non-terminated) Inputs. 2RE* Receiver Output Enable: When RE* is LOW the receiver output is enabled. When RE* is HIGH, the receiver output

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http://www.national.com 8

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Physical Dimensions inches (millimeters) 8-Lead (0.150× Wide) Molded Small Outline Package, JEDEC Order Number DS36C278TM, DS36C278M NS Package Number M08A 9 http://www.national.com

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Physical Dimensions inches (millimeters) (Continued) 8-Lead (0.300× Wide) Molded Dual-In-Line Package Order Number DS36C278TN, DS36C278N NS Package Number N08E LIFE SUPPORT POLICY NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or 2. A critical component is any component of a life syste