ADM489ARZ - 250 kbps Full-Duplex RS-485/RS-422 Transceiver | Analog Devices
Teilenummer: ADM489ARZ ✓ AktivADM489ARZ Übersicht
An RS-485 transceiver is the physical-layer building block that converts a logic-level serial signal into a balanced differential signal for transmission over long, noisy cables, and converts the returning differential signal back into a logic-level output. The RS-485 standard defines a differential bus in which multiple receivers may listen to one driver pair, making it the most widely deployed industrial serial interface for factory automation, instrumentation, building controls, and networked sensors. The RS-422 companion standard adds point-to-point, full-duplex capability, which is exactly what the ADM489 implements with separate driver and receiver pin pairs.
Key features of the ADM489ARZ include slew-rate limiting for reduced EMI and reflection, compliance with the EIA RS-485 and RS-422 standards, a 250 kbps data rate that comfortably covers legacy industrial protocols such as Modbus RTU at 19.2 kbps to 115.2 kbps, and tolerance of supply variation of plus or minus 10 percent around the nominal 5 V rail. Slew-rate-limited edges are the main reason the ADM489 is preferred over faster parts in noisy cabinet environments, since they suppress the ringing that causes false start bits and CRC errors.
Architecturally the device combines a differential line driver, a differential receiver with fail-safe biasing, and separate active-high driver-enable and active-low receiver-enable inputs. That separation allows the two directions of the full-duplex link to be managed independently, so a system can hold its bus driver disabled in listen-only mode without tying up the receive path. The 14-pin SOIC footprint gives adequate lead spacing for hand assembly and automated pick-and-place while keeping the board area small.
Typical deployments include industrial PLC and DCS remote I/O modules, RS-485 to RS-232 gateways, building HVAC controllers, utility and metering equipment, CNC machine tools, and long-cable sensor networks. The 250 kbps ceiling also suits legacy barcode scanners, weigh bridges, and access-control readers that use RS-485 or RS-422 over single runs of cable.
A key design consideration is that the differential pair must be routed as a matched, tightly coupled pair over a continuous ground reference, with termination resistors of 100 ohm or 120 ohm fitted only at the two physical ends of the bus. Keep the transceiver close to the connector so that unbalanced stub lengths stay short, and decouple the 5 V supply locally with a 100 nF ceramic capacitor plus a bulk capacitor near the device.
This page consolidates device specifications, drop-in pin-compatible alternatives, a parameter-by-parameter comparison table, and practical RS-485 layout and termination guidance that designers normally have to piece together from several separate documents.
Drop-in-Alternativen für ADM489ARZ – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit ADM489ARZ (gleiche Bauform und Footprint).
MAX489ESA+
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
MAX489CSD+
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
MAX3071ESE+
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
MAX3485ESD+
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
ISL8489EIBZ
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
ADM489ARZ Technische Daten
| Number of Drivers/Receivers | 1/1 |
| Transceiver Type | Full-duplex differential line transceiver |
| Supported Protocols | RS-422, RS-485 |
| Standard Compliance | EIA RS-485 and EIA RS-422 |
| Supply Voltage Range | 4.5 V to 5.5 V |
| Datenrate | 250 kbps |
| Edge Rate Control | Slew-rate limited |
| Supply Variation Tolerance | +/-10% |
| Gehäuse / Bauform | 14-SOIC (0.154 in, 3.90 mm width) |
| Packaging | Tube |
| Montageart | Surface Mount |
| Driver Enable | Active-high DE input |
| Receiver Enable | Active-low /RE input |
ADM489ARZ Pin-Konfiguration
| Pin 1 | RO — Receiver output (logic-level data from the bus) |
| Pin 2 | /RE — Receiver enable, active low |
| Pin 3 | DE — Driver enable, active high |
| Pin 4 | DI — Driver input (logic-level data to be transmitted) |
| Pin 5 | GND — Ground (logic side reference) |
| Pin 6 | VCC — Positive supply, 4.5 V to 5.5 V |
| Pin 7 | Y — Driver output (non-inverting differential output) |
| Pin 8 | Z — Driver output (inverting differential output) |
| Pin 9 | Y — Receiver input (non-inverting differential input) |
| Pin 10 | Z — Receiver input (inverting differential input) |
| Pin 11 | GND — Ground (bus side reference) |
| Pin 12 | NC — Not connected (per datasheet) |
| Pin 13 | NC — Not connected (per datasheet) |
| Pin 14 | NC — Not connected (per datasheet) |
Typische Anwendungen
ADM489ARZ ist geeignet für 6 Anwendungs: Industrial PLC Remote I/O Module, Building HVAC and Controller Network, RS-485 to RS-232 Protocol Gateway, Utility Metering and Data Acquisition, CNC Machine Tool and Robotics Control, Long-Cable Sensor and Barcode Network.
Industrial PLC Remote I/O Module
The ADM489ARZ suits remote I/O cards that sit on an RS-485 backbone between a PLC and field sensors. Its full-duplex architecture keeps the transmit and receive paths independent, so the module can hold the driver disabled in listen-only mode while the controller polls the bus, which is exactly the multi-drop discipline the RS-485 standard requires. With a 250 kbps ceiling, the part supports Modbus RTU at 19.2 kbps to 115.2 kbps over several hundred metres of cable without risking reflections, and the slew-rate-limited driver keeps radiated emissions inside the limits that industrial cabinets demand. Termination of 120 ohm is fitted only at the two physical ends of the segment, while each card keeps its stub to the connector short to preserve signal integrity.
Empfohlen
Building HVAC and Controller Network
HVAC panels, room controllers and VAV damper actuators are commonly wired with RS-485 so that a single cable run links dozens of field devices back to a floor controller. The ADM489ARZ operates from a single 5 V rail between 4.5 V and 5.5 V, which matches the regulated rails already present in building controllers and simplifies the power tree. Because its edges are slew-rate limited, the transceiver is far quieter on the cable than a 12 Mbps alternative, reducing common-mode noise that would otherwise couple into adjacent thermostat and lighting circuits running in the same conduit. The device also tolerates supply variation of plus or minus 10 percent, so it keeps working through brown-out conditions on building power without a separate supervisor.
Empfohlen
RS-485 to RS-232 Protocol Gateway
Gateways that translate between legacy RS-232 ports on a PC or instrument and an RS-485 field network are a classic home for a full-duplex transceiver. The ADM489ARZ gives the gateway two independent differential pairs, so the RS-232 side can be received while the RS-485 side transmits without turnaround delays. Using one chip for both directions keeps the board area small in a DIN-rail enclosure where space is at a premium, and the 14-pin SOIC outline is compatible with standard automated assembly and pick-and-place libraries. For designs that need galvanic isolation, the same bus can instead be terminated with an isolated transceiver such as the ISO1042BDWR while keeping identical firmware and connector assignments.
Empfohlen
Utility Metering and Data Acquisition
Electric, gas and water metering clusters are often distributed over RS-485 in outdoor cabinets where temperature swings and electromagnetic interference are severe. The ADM489ARZ's slew-rate-limited output dramatically reduces the high-frequency content on the pair, which limits both radiated emissions and susceptibility to coupling from adjacent power cables. The receiver side, with its differential input, rejects common-mode noise that would otherwise be rectified by a single-ended input, improving the integrity of the pulse-width and amplitude information that metering protocols rely on. Because the transceiver is a legacy 250 kbps class device, it works with the many installed master meters and concentrators that predate faster 1 Mbps hardware, which removes a costly field upgrade from the project plan.
Empfohlen
CNC Machine Tool and Robotics Control
Machine tool controllers and robot teach pendants distribute servo and safety I/O over RS-422 point-to-point links, where the full-duplex capability of the ADM489ARZ is a direct benefit. Because RS-422 allows continuous bidirectional transmission with no arbitration, position feedback can stream in the reverse direction at the same time as commands, and the independently controlled driver-enable and receiver-enable inputs let the controller park the outputs in a safe state during a fault. Slew-rate-limited edges also help in electrically noisy machine environments where a faster transceiver would ring on imperfectly terminated cabling. The 250 kbps rate is well above the bandwidth needed for typical axis status and program-transfer traffic on these links.
Empfohlen
Long-Cable Sensor and Barcode Network
Sensor hubs, weigh bridges and barcode readers in warehouses are frequently daisy-chained with RS-485 over cable runs that cross between buildings or buildings and loading bays. The ADM489ARZ was designed for exactly this condition: a 250 kbps rate that still delivers usable margin at 115.2 kbps, and slew-rate-limited edges that keep the differential pair from exciting cable resonances. The receiver's differential architecture tolerates the common-mode voltage that develops between the grounds of widely separated devices, so a single reference ground per segment is usually sufficient. Using the same 14-pin SOIC package as the alternatives in this family means a redesign during component sourcing can be absorbed with a footprint change rather than a board respin.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für ADM489ARZ – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | MAX489ESA+ | MAX489CSD+ | MAX3071ESE+ | MAX3485ESD+ | ISL8489EIBZ |
|---|---|---|---|---|---|---|
| Package | SOIC-14 (14-SOIC, 0.154 in / 3.90 mm width) | SOIC-14 - same | SOIC-14 - same | SOIC-14 - same | SOIC-14 - same | SOIC-14 - same |
| Brand | Analog Devices | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Renesas Electronics |
| Protocols | RS-422, RS-485 | RS-422, RS-485 | RS-422, RS-485 | RS-422, RS-485 | RS-422, RS-485 | RS-422, RS-485 |
| Number of Drivers/Receivers | 1/1 full duplex | 1/1 full duplex | 1/1 full duplex | 1/1 full duplex | 1/1 full duplex | 1/1 full duplex |
| Supply Voltage Range | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 3.3 V to 5.5 V | 3 V to 5.5 V |
| Maximum Data Rate | 250 kbps | 250 kbps | 250 kbps | 1 Mbps | 12 Mbps | 250 kbps class low-power |
| Output Edge Control | Slew-rate limited | Slew-rate limited | Slew-rate limited | Slew-rate limited | High-speed, no slew-rate limiting | Slew-rate limited, low power |
| Packaging | Tube, 14-SOIC | Tube, SOIC-14 | Tube, SOIC-14 | Tube, SOIC-14 | Tape and reel, SOIC-14 | Tube, SOIC-14 |
| Driver / Receiver Enable Control | Active-high DE and active-low /RE inputs | Active-high DE and active-low /RE inputs | Active-high DE and active-low /RE inputs | Active-high DE and active-low /RE inputs | Active-high DE and active-low /RE inputs | Enable polarities to confirm in the ISL8489 datasheet |
Wichtigste Unterscheidungsmerkmale
- Slew-rate-limited driver for noisy industrial cabinets (vs. MAX3485ESD+)
- 250 kbps rate matches the installed Modbus RTU infrastructure (vs. MAX3071ESE+)
- Single 4.5 V to 5.5 V rail with +/-10% supply variation tolerance (vs. ISL8489EIBZ)
- Established Analog Devices interface family with a documented 14-SOIC footprint (vs. MAX489ESA+)
Designhinweise
Place the ADM489ARZ as close as practical to the RS-485 connector and route the Y and Z driver outputs and receiver inputs as a tightly coupled pair with a continuous ground reference beneath them. Keep stubs short, avoid vias in the differential pair where possible, and keep the pair away from switching nodes such as inductors and clocked power stages. A common mistake is splitting the driver and receiver nets onto separate layers, which destroys the common-mode cancellation that makes the differential receiver work.
Terminate the bus at both physical ends only, with 100 ohm to 120 ohm across the pair, and never add termination at every node in a multi-drop installation. Fit a biasing network at a single location on the bus so the line idles at a valid differential state; without bias, the ADM489 receiver can output noise during bus turnaround. Also note that the active-high DE and active-low /RE pins are frequently wired together, and tying DE high while the driver input floats can drive the bus and cause contention.
Decouple the 5 V supply at the device with a 100 nF ceramic capacitor placed within a few millimetres of the VCC and GND pins, plus a bulk electrolytic or 1 uF to 10 uF ceramic for longer-distance or high-noise installations. The ADM489ARZ operates from 4.5 V to 5.5 V and tolerates supply variation of plus or minus 10 percent, but local decoupling determines how much of the supply noise actually reaches the receiver threshold. Estimated: with a 250 mA average bus load, a 100 mV supply step at the pins would shift the receiver threshold by 20 mV, so keep the supply impedance low.
Because the ADM489ARZ is slew-rate limited, most of its spectrum sits in the low-MHz region where cable radiation is easier to control than for a 12 Mbps part. If the installation also carries a separate high-speed RS-485 segment on the same board, keep the two pairs physically apart and cross no ground discontinuity, since a broken ground under the pair destroys the common-mode rejection the receiver depends on. Chassis ground should be bonded to signal ground at a single point near the connector for predictable behaviour.
Compliance-Informationen
The ADM488/ADM489 datasheet describes EIA RS-485 and RS-422 compliance; no explicit RoHS, REACH, lead-free or AEC-Q100 statement was available for this part number, so those fields remain unconfirmed.
