ADM2481 2.5 kV Signal Isolated, 500 kbps, Half Duplex RS-485 Transceiver

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. Applications Low power RS-485/RS-422 networks Isolated interfaces Building control networks Multipoint data transmission systems

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.

Features and Benefits

RS-485 transceiver with electrical data isolation
Complies with ANSI TIA/EIA-485-A and ISO 8482: 1987(E)
500 kbps data rate
Slew rate-limited driver outputs

Low power operation: 2.5 mA maximum
Suitable for 5 V or 3.3 V operations (VDD1)
High common-mode transient immunity: >25 kV/μs
See data sheet for additional features

Interface & Isolation

Isolated RS-485

Data Sheets

Document	note
ADM2481: Half-Duplex, iCouplerIsolated RS-485 Transceiver (Rev. A)	PDF 275 kB

Application Notes

Document	note
AN-1179: Junction Temperature Calculation for Analog Devices RS-485/RS-422, CAN, and LVDS/M-LVDS Transceivers (Rev. A)	PDF 156.87 K
AN-1176: Component Footprints and Symbols in the Binary .Bxl File Format (Rev. 0)	PDF 671 kB
AN-960: RS-485/RS-422 Circuit Implementation Guide (Rev. 0)	PDF 245 kB