The ADM2481 differential bus transceiver is an integrated, galvanically isolated component designed for bidirectional data communication on balanced, multipoint bus transmission lines. It complies with ANSI EIA/TIA-485-A and ISO 8482: 1987(E). Using iCoupler® technology from Analog Devices, Inc., the ADM2481 combines a 3-channel isolator, a three-state differential line driver, and a differential input receiver into a single package. The logic side of the device is powered with either a 5 V or 3 V supply, and the bus side uses a 5 V supply only.
The ADM2481 is slew-limited to reduce reflections with improperly terminated transmission lines. The controlled slew rate limits the data rate to 500 kbps. The input impedance of the device is 96 kΩ, allowing up to 256 transceivers on the bus. Its driver has an active-high enable feature. The driver differential outputs and receiver differential inputs are connected internally to form a differential I/O port. When the driver is disabled or when VDD1 or VDD2 = 0 V, this imposes minimal loading on the bus. An active-high receiver disable feature, which causes the receiver output to enter a high impedance state, is provided as well.
The receiver inputs have a true fail-safe feature that ensures a logic-high receiver output level when the inputs are open or shorted. This guarantees that the receiver outputs are in a known state before communication begins and at the point when communication ends.
Current limiting and thermal shutdown features protect against output short circuits and bus contention situations that might cause excessive power dissipation. The part is fully specified over the industrial temperature range of −40°C to +85°C and is available in a 16-lead, wide body SOIC package.Applications
|Title||Content Type||File Type|
|ADM2481: Half-Duplex, iCouplerIsolated RS-485 Transceiver (Rev A, 06/2012) (pdf, 275 kB)||Data Sheets|
|AN-960: RS-485/RS-422 Circuit Implementation Guide (pdf, 245 kB)||Application Notes|
Solving Isolation Challenges in Industrial Automation
This webcast will discuss the role isolation plays in providing protection and reducing the system bit-error-rate, using the specific design challenges of an RS-485 network. Topics to be covered in this presentation will include: Why and when one should isolate, Types of isolation and their advantages, Design Considerations for an RS-485 node (and how this translates to design considerations for signal isolation) as well as many other topics.
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High-Performance Multichannel Power-Line Monitoring with Simultaneous-Sampling ADCs
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The ezLINX™ iCoupler® Isolated Interface Development Environment provides developers with a cost-effective, plug and play method for evaluation eight physical layer, digitally-isolated communication standards.
Evaluation board for evaluating the ADM2481 2.5 kV Signal Isolated, 500 kbps, Half Duplex RS-485 Transceiver
Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.
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