ADM1485ARZ - 30 Mbps 5V RS-485/RS-422 Half-Duplex Transceiver | ADI
MPN: ADM1485ARZ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.93 | $4.93 |
| 10 | $4.41 | $44.10 |
| 100 | $3.62 | $362.00 |
| 500 | $3.12 | $1,560.00 |
| 1,000 | $2.8 | $2,800.00 |
ADM1485ARZ Overview
What is an RS-485/RS-422 transceiver? It is a physical-layer interface IC that converts a single-ended TTL/CMOS logic signal from a UART, MCU, or FPGA into a differential signal suitable for transmission over twisted-pair cable, and vice versa. RS-485 supports multipoint, half-duplex or full-duplex buses with up to 32 unit loads and common-mode voltages up to ±12 V, while RS-422 is its point-to-point/point-to-multipoint predecessor with similar differential signaling. Transceivers sit at the bottom of the OSI physical layer, bridging digital logic to industrial bus standards such as Profibus, Modbus, DMX512, and BACnet.
Key specifications include a maximum data rate of 30 Mbps (with low driver skew for minimal EMI), a single 5 V supply (4.75 V to 5.25 V), ±12 V bus common-mode range, 70 mV receiver hysteresis, BiCMOS construction for low power, and on-chip thermal shutdown plus short-circuit protection. The differential driver outputs are well balanced to ensure distortion-free transmission, and minimal propagation delay supports high-speed industrial links without timing margin loss.
Architecturally, the ADM1485ARZ uses BiCMOS process technology that combines the low power consumption of CMOS with the high drive capability of bipolar transistors. The result is a robust transceiver that draws minimal quiescent current while still swinging RS-485 levels into 60 ohm loads (two 120 ohm terminations in parallel). Internal fail-safe biasing on the receiver inputs guarantees a defined logic-high output when the bus is idle or open.
Typical applications include industrial fieldbus networks (Profibus, Modbus), building automation (BACnet, DMX512 lighting), point-of-sale and banking terminals, motor drive feedback links, and any half-duplex multidrop RS-485 wiring run. The wide common-mode range makes the part tolerant of ground-potential differences between nodes in factory environments.
When designing with the ADM1485ARZ, place the IC close to the bus connector and use a 100 ohm differential termination at each end of the cable. For multi-node buses, fail-safe biasing resistors (typically a pull-up on B and pull-down on A) may be needed if the part is operated without termination. The half-duplex design requires firmware control of the DE and RE pins, which can be tied together when only one direction is active at a time.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for ADM1485ARZ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADM1485JRZ-REEL
📋 Reference alternative (not in catalog)
ADM485ARZ
📋 Reference alternative (not in catalog)
ADM1491EBRZ
📋 Reference alternative (not in catalog)
SN65HVD72DR
📋 Reference alternative (not in catalog)
ST3485EIDR
📋 Reference alternative (not in catalog)
MAX3485ESA
📋 Reference alternative (not in catalog)
ADM1485ARZ Specifications
| Protocol | RS-422, RS-485 |
| Number of Drivers/Receivers | 1/1 |
| Duplex | Half |
| Data Rate | 30 Mbps |
| Receiver Hysteresis | 70 mV |
| Supply Voltage | 4.75 V to 5.25 V (5 V nominal) |
| Bus Common-Mode Range | -7 V to +12 V |
| Operating Temperature Range | -40 °C to +85 °C |
| Package / Case | 8-SOIC (0.154", 3.90 mm Width) |
| Mounting Type | Surface Mount |
| Packaging | Tube |
| Process Technology | BiCMOS |
| Features | Thermal Shutdown, Short-Circuit Protection |
| Standards Compliance | EIA RS-485, EIA RS-422 |
| RoHS Status | Compliant |
ADM1485ARZ Pin Configuration
| Pin 1 | RO — Receiver Output (logic-level TTL output) |
| Pin 2 | RE — Receiver Enable (active-low) |
| Pin 3 | DE — Driver Enable (active-high) |
| Pin 4 | DI — Driver Input (logic-level TTL input) |
| Pin 5 | GND — Ground |
| Pin 6 | A/Y — Non-inverting driver output / non-inverting receiver input |
| Pin 7 | B/Z — Inverting driver output / inverting receiver input |
| Pin 8 | VCC — +5 V supply |
Typical Applications
ADM1485ARZ is suitable for 6 applications: Industrial Fieldbus Networks, Building Automation & HVAC, DMX512 Stage Lighting Control, Motor Drive Encoder Feedback, Point-of-Sale & Access Control, Telecom Base Station Backhaul.
Industrial Fieldbus Networks
The ADM1485ARZ is well-suited for industrial fieldbus networks such as Profibus DP, Modbus RTU, and BACnet MS/TP that run over half-duplex RS-485 wiring. Its 30 Mbps headroom supports Modbus and Profibus rates of 1-12 Mbps with substantial timing margin, and the ±12 V bus common-mode range tolerates ground-potential differences between PLC cabinets and remote I/O racks on a factory floor. The BiCMOS driver delivers 60 ohm differential drive capability into two parallel terminations for long multidrop trunk runs. Industrial designs benefit from the -40 to +85 °C operating range that covers unconditioned factory environments without needing extra thermal management.
Recommended
Building Automation & HVAC
Building automation controllers rely on RS-485 to link VAV boxes, smart thermostats, lighting dimmers, and air-handling units across long runs of twisted-pair cabling. The ADM1485ARZ's 30 Mbps capability and ±12 V common-mode tolerance handle the cable lengths (up to 1200 m) and ground offsets encountered in commercial buildings. Its half-duplex topology suits the polled master-slave traffic pattern of BACnet MS/TP. The internal thermal-shutdown and short-circuit protection prevent field-wiring faults from damaging controllers during installation or maintenance cycles.
Recommended
DMX512 Stage Lighting Control
DMX512 lighting rigs use half-duplex RS-485 at 250 kbps to chain dimmer packs, moving lights, and LED fixtures. Although the data rate is well below the ADM1485ARZ's 30 Mbps maximum, the chip's fast edge rates deliver clean waveforms that reduce ringing on long daisy-chained cable runs, and its ±12 V common-mode tolerance prevents dimmer-related ground noise from corrupting control packets. Many lighting designers standardize on the ADM1485 family so the same PCB BOM works for DMX, RDM, and higher-speed proprietary lighting protocols.
Recommended
Motor Drive Encoder Feedback
Servo drives and variable-frequency drives use RS-485 to communicate encoder position, torque commands, and diagnostic data between the drive and the controller cabinet. The ADM1485ARZ's 30 Mbps capability easily handles 16-bit encoder data at 32 kHz update rates, while its BiCMOS construction keeps quiescent current low enough that it can share the drive's isolated 5 V supply without loading concerns. The on-chip short-circuit and thermal protection are especially valuable in motor-drive environments where bus miswiring during commissioning is a common fault mode.
Recommended
Point-of-Sale & Access Control
POS terminals, EFT/PIN pads, RFID readers, and access-control panels often communicate over RS-485 to consolidate cabling in retail and security installations. The ADM1485ARZ provides the 5 V logic interface common in industrial embedded designs, and the 30 Mbps data rate headroom supports high-speed firmware update transfers during maintenance windows. The robust ±12 V common-mode range tolerates ground offsets between back-office terminals and remote door controllers powered from different branch circuits.
Recommended
Telecom Base Station Backhaul
Distributed antenna systems and small-cell base stations use RS-485 to link remote radio heads (RRH) to baseband units over shielded twisted pair. The ADM1485ARZ's 30 Mbps capacity supports proprietary CPRI-over-RS-485 links and AISG (Antenna Interface Standards Group) tower-mounted equipment control. The -40 to +85 °C industrial temperature rating handles outdoor cabinet environments, while the BiCMOS low-power design contributes minimal heat to the sealed enclosure.
Recommended
Recommended Products Summary
Engineering reference data for ADM1485ARZ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADM1485JRZ-REEL | ADM485ARZ | SN65HVD72DR | ST3485EIDR | MAX3485ESA |
|---|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Texas Instruments | STMicroelectronics | Maxim Integrated |
| Package | 8-SOIC | 8-SOIC (same) | 8-SOIC (same) | 8-SOIC (same) | 8-SOIC (same) | 8-SOIC (same) |
| Data Rate | 30 Mbps | 30 Mbps | 5 Mbps | 30 Mbps | 20 Mbps | 12 Mbps |
| Supply Voltage | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 3.6 V |
| Duplex | Half | Half | Half | Half | Half | Half |
| Drivers/Receivers | 1/1 | 1/1 | 1/1 | 1/1 | 1/1 | 1/1 |
| Receiver Hysteresis | 70 mV | 70 mV | 70 mV | 50 mV | 70 mV | 60 mV |
| Bus Common-Mode Range | -7 V to +12 V | -7 V to +12 V | -7 V to +12 V | -25 V to +25 V (extended) | -7 V to +12 V | -7 V to +12 V |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +125 °C | -40 °C to +85 °C | -40 °C to +85 °C |
Key Differentiators
- 30 Mbps headroom for high-speed fieldbus and backplane links (vs ADM485ARZ)
- Extended ±25 V common-mode range alternative available from TI (vs SN65HVD72DR)
- 5 V native supply ideal for legacy 5 V-only MCU systems (vs MAX3485ESA)
Design Notes
Place the ADM1485ARZ as close as practical to the bus connector (D-sub or terminal block) to keep the differential trace between the IC and connector short. Route the A/Y and B/Z pair as a matched-impedance differential pair (typically 100 ohm differential) over a continuous ground reference plane. Avoid splitting the ground plane beneath the bus traces; split planes inject common-mode noise that can corrupt the receiver's high-impedance input. Place 100 nF and 10 uF decoupling capacitors within 3 mm of the VCC pin, with the smaller ceramic closest to the IC.
A common mistake is leaving both DE and RE floating. For half-duplex operation, RE must be tied low (active) and DE driven by the UART's direction control; alternatively, tie RE-bar to ground and tie DE high during transmit, low during receive. Floating DE/RE pins can leave the driver in an indeterminate state and cause excessive bus current or crosstalk. Also ensure 100 ohm termination resistors are placed ONLY at the two physical ends of the bus trunk - termination in the middle causes signal reflections and reduces noise margin. Estimated: at 30 Mbps with 5 ns propagation delay, improper termination can corrupt the last bit of every byte.
For cables longer than 10 m at 30 Mbps, use twisted-pair cable with characteristic impedance of 100-120 ohms and add a 100 ohm termination resistor at each cable end. If your design must support hot-plug of nodes, add series resistors (10-33 ohm) in the A/Y and B/Z lines near the connector to limit inrush current and damp transient ringing. The ADM1485ARZ's ±12 V common-mode range is robust but does not protect against sustained over-voltage events; for outdoor installations, add external TVS diodes (e.g., SMAJ12CA) from A/Y and B/Z to ground.
The ADM1485ARZ draws minimal quiescent current in idle state (driver and receiver disabled), but the supply current rises to several tens of mA when the driver is actively switching into a 60 ohm load. Ensure the 5 V regulator feeding the part can source at least 100 mA with adequate decoupling (10 uF bulk + 100 nF local). In noisy industrial environments, add a ferrite bead between the regulator and the transceiver's VCC pin to attenuate high-frequency noise from the digital logic supply.
Compliance Information
RoHS and REACH compliant per ADI product page. Lead-free (Pb-free) packaging confirmed. Halogen-free status not explicitly stated in retrieved data - see _validation_note.
