MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-LimitedRS-485/RS-422 TransceiversLine Length vs. Data RateThe RS-485/RS-422 standard covers line lengths up to4000 feet. For line lengths greater than 4000 feet, seeFigure 23.
Figures 19 and 20 show the system differential voltagefor the parts driving 4000 feet of 26AWG twisted-pairwire at 110kHz into 120Ωloads.
Figures 21 and 22 show typical network applicationscircuits. These parts can also be used as linerepeaters, with cable lengths longer than 4000 feet, asshown in Figure 23.
To minimize reflections, the line should be terminated atboth ends in its characteristic impedance, and stublengths off the main line should be kept as short as possi-ble. The slew-rate-limited MAX483 and MAX487–MAX489are more tolerant of imperfect termination.
Typical ApplicationsThe MAX481, MAX483, MAX485, MAX487–MAX491, andMAX1487 transceivers are designed for bidirectional datacommunications on multipoint bus transmission lines.
DI5V0VDI5V0V1VVY-VZ0V-1VVY-VZ1V0V-1VRO5V0VRO5V0V2μs/div2μs/divFigure 19. MAX481/MAX485/MAX490/MAX491/MAX1487 SystemDifferential Voltage at 110kHz Driving 4000ft of CableFigure 20. MAX483, MAX487–MAX489 System DifferentialVoltage at 110kHz Driving 4000ft of Cable120ΩDIB120ΩBDEDDEROREABABAADDIRRDDRROREMAX481MAX483MAX485MAX487MAX1487RDIDEROREDIDEROREFigure 21. MAX481/MAX483/MAX485/MAX487/MAX1487 Typical Half-Duplex RS-485 Network13
MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487Low-Power, Slew-Rate-LimitedRS-485/RS-422 TransceiversAROREDEZDIY120Ω120ΩZDEB120Ω120ΩYZBAYZBAARERORBDDIDYRRDDRMAX488–MAX491DIDERERODIDERERONOTE: RE AND DE ON MAX489/MAX491 ONLY.Figure 22. MAX488–MAX491 Full-Duplex RS-485 NetworkIsolated RS-485MAX488–MAX491For isolated RS-485 applications, see the MAX253 andMAX1480 data sheets.
AROREDEDIRB120ΩDATA INZD120ΩYDATA OUTNOTE: RE AND DE ON MAX489/MAX491 ONLY.Figure 23. Line Repeater for MAX488–MAX49114
MEMORY存储芯片MAX5035BASA+T中文规格书 - 图文
