Half-Duplex, Coupler Isolated RS-485 Transceiver

The ADM2483 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 the iCoupler technology from Analog Devices, Inc., the ADM2483 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 ADM2483 is slew-limited to reduce reflections with improperly terminated transmission lines. The controlled slew rate limits the data rate to 500 kbps. The device’s input impedance 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 input/output (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 receive 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 and is available in a 16-lead, wide body SOIC package.

Applications

* Low power RS-485/RS-422 networks

* Isolated interfaces

* Building control networks

* Multipoint data transmission systems

* RS-485 transceiver with electrical data isolation

* Complies with ANSI TIA/EIA RS-485-A and ISO 8482: 1987(E)

* 500 kbps data rate

* Slew rate-limited driver outputs

* Low power operation: 2.5 mA max

* Suitable for 5 V or 3 V operations (VDD1)

* High common-mode transient immunity: >25 kV/μs

* True fail-safe receiver inputs

* Chatter-free power-up/power-down protection

* 256 nodes on bus

* Thermal shutdown protection

* Safety and regulatory approvals

* UL recognition: 2500 V rms for 1 minute per UL 1577

* CSA Component Acceptance Notice 5A

* UL 1577

* VISO = 2500 VRMS for 1 minute

* IEC/CSA 62368-1

* IEC/CSA 60601-1

* IEC/CSA 61010-1

* CQC GB4943.1

* DIN EN IEC 60747-17 (VDE 0884-17)

* VIORM = 565 V peak

* Operating temperature range: −40°C to +85°C