RS485
来自Jack's Lab
(版本间的差异)
(→Hardware) |
(→MAX485) |
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第17行: | 第17行: | ||
* 0.1µA Low-Current Shutdown Mode (MAX481/483/487) | * 0.1µA Low-Current Shutdown Mode (MAX481/483/487) | ||
* Low Quiescent Current: | * Low Quiescent Current: | ||
− | + | **120µA (MAX483/487/488/489) | |
− | + | **230µA (MAX1487) | |
− | + | **300µA (MAX481/485/490/491) | |
* -7V to +12V Common-Mode Input Voltage Range | * -7V to +12V Common-Mode Input Voltage Range | ||
* Three-State Outputs | * Three-State Outputs |
2017年9月16日 (六) 13:56的版本
目录 |
1 Overview
RS-485 在多数情况下,由于应用环境的恶劣,需采用隔离方案以防止出现接地环路。
光耦隔离电路占用空间大,需要分立元件、缓存驱动, 但成本便宜
ADI 的 iCoupler 磁隔离解决方案,它能够提供多通道数字隔离、集成 RS-485 收发器的数字隔离、集成 isoPower 磁隔离电源的数字隔离等多种灵活的隔离方案。在体积、功耗、速率等众多方面优于光耦的解决方案
2 Hardware
2.1 MAX485
- In µMAX Package: Smallest 8-Pin SO
- Slew-Rate Limited for Error-Free Data Transmission (MAX483/487/488/489)
- 0.1µA Low-Current Shutdown Mode (MAX481/483/487)
- Low Quiescent Current:
- 120µA (MAX483/487/488/489)
- 230µA (MAX1487)
- 300µA (MAX481/485/490/491)
- -7V to +12V Common-Mode Input Voltage Range
- Three-State Outputs
- 30ns Propagation Delays, 5ns Skew (MAX481/485/490/491/1487)
- Full-Duplex and Half-Duplex Versions Available
- Operate from a Single 5V Supply
- Allows up to 128 Transceivers on the Bus (MAX487/MAX1487)
- Current-Limiting and Thermal Shutdown for Driver Overload Protection
Need B0505 DC-DC and PS2501
- RS485_1_A+ --- MAX485_PIN6
- RS485_1_B- --- MAX485_PIN7
- MAX485_PIN4 --- ARM9_CORE_J2_68_TXD0
- MAX485_PIN1 --- ARM9_CORE_J2_69_RXD0
- MAX485_PIN2 & 3 --- ARM9_CORE_J1_69_PC30
2.2 ISL3152E
- High driver VOD 2.4V (Min) at RD = 54Ω Better noise immunity, or drive up to eight terminations
- ±16.5kV IEC61000 ESD protection on I/O bus pins
- High transient overvoltage tolerance . . . . . ±100V
- Full fail-safe (open, short, terminated) receivers
- High Rx IOL for opto-couplers in isolated designs
- Hot plug circuitry - Tx and Rx outputs remain three-state during power-up and power-down
- True 1/8 unit load for up to 256 devices on the bus
- High data rates . . . . . . . . . . . . . . . up to 20Mbps
- Low quiescent supply current . . . . . . . . . . 600µA
- Ultra low shutdown supply current . . . . . . . . 70nA
- http://www.intersil.com/content/dam/Intersil/documents/isl3/isl3150e-52e-53e-55e-56e-58e.pdf
- http://www.intersil.com/content/dam/Intersil/whitepapers/interface/rs-485-transceiver-tutorial_cn.pdf
- http://www.intersil.com/content/dam/Intersil/documents/an19/an1986.pdf
2.3 ADM2483
Also need the B0505 DC-DC
2.4 ISO3082
Also need the B0505 DC-DC
2.5 ADM2587
ADM2582E/ADM2587E 以单芯片实现完全的半/全双工RS-485接口隔离。ADM2582E/ADM2587E 集成 isoPower 磁隔离电源,无需外部隔离电源供电。还集成了数字隔离通道和 RS-485 收发器,具备±15 kV ESD 保护功能,适用于多点传输线路上的高速通信应用。
其内部集成的 RS-485 驱动器带有一个高电平有效使能电路,并且还提供一个高电平接收机有效禁用电路,可使接收机输出进入高阻抗状态。该器件具备限流和过热关断特性,能够防止输出短路,并防止出现由于总线争用而引起功耗过大的情况。
芯片封装为 SOIC-20
全双工RS-485/RS-422:
半双工RS-485/RS-422:
3 Reference