MAX22025AWA+ - 3.5kVRMS Isolated RS-485 Transceiver | ADI
MPN: MAX22025AWA+ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.85 | $4.85 |
| 10 | $4.36 | $43.60 |
| 100 | $3.88 | $388.00 |
| 500 | $3.49 | $1,745.00 |
| 1,000 | $3.1 | $3,100.00 |
MAX22025AWA+ Overview
An RS-485/RS-422 transceiver is a differential line driver/receiver IC that translates a single-ended UART signal into a balanced differential pair. The differential signaling inherent to RS-485 enables robust communication over long cable runs (up to 1200m) with strong common-mode noise rejection. Galvanic isolation extends this robustness by separating the cable-side ground potential from the local controller ground, which is essential when the bus spans multiple power domains or is exposed to high transient voltages. Isolated transceivers are a key sub-category of interface ICs, themselves part of the broader mixed-signal semiconductor hierarchy.
Key features include ±35kV ESD protection on the bus pins (HBM), short-circuit protection on the driver outputs, thermal shutdown, and 1/8 unit-load receiver input impedance allowing up to 256 transceivers on a single bus. The integrated isolation barrier replaces discrete optocouplers and isolated power, typically shrinking the BOM by 40-60% and reducing PCB footprint to roughly 80mm². The device supports -40°C to +85°C operation and is specified over a wide 3.0V to 5.5V UART-side VDD range.
Architecturally, the MAX22025 uses Maxim's proprietary capacitive isolation technology with an OOK-modulated carrier across the barrier. The cable-side driver meets the RS-485 standard's 1.5V minimum differential output with 54Ω load, while the receiver hysteresis (typ. 30mV) ensures clean switching even on heavily attenuated signals. On-chip deglitch filters suppress transient bus spikes up to 150ns.
Typical applications include isolated RS-485 nodes in industrial PLCs, solar inverter modbus links, battery management system (BMS) communication, HVAC controllers, and any 4-20mA replacement using RS-485 over a galvanically-isolated link. It is also well-suited for fieldbus gateways, smart-grid metering, and remote sensor data acquisition where ground-potential differences exceed hundreds of volts.
When designing with the MAX22025AWA+, observe the creepage and clearance rules of IEC 60664-1 on the PCB to preserve the rated isolation. A bypass capacitor of 0.1µF must be placed within 2mm of each supply pin; the UART-side and cable-side grounds must remain separate, joined only through the device's internal barrier. Verify the driver slew rate at your chosen data rate to control EMI.
Drop-in alternatives for MAX22025AWA+ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MAX22025AWA+ (same form factor and footprint) — differing in Duplex, Function, Operating Temperature, Package, Data Rate (max).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX22025AWA+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX22027AWA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX22028AWA+
✅ Drop-In✓ In Stock
$3.45 / Unit
View Datasheet →MAX22026AWA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX14852GWE+
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$7.25 / Unit
View Datasheet →MAX22025AWA+ Specifications
| Function | Transceiver, Isolated RS-485/RS-422 |
| Number of Drivers/Receivers | 1/1 |
| Duplex | Half |
| Data Rate (max) | 500 kbps |
| Isolation Voltage | 3.5 kVRMS |
| UART-Side Supply Voltage | 3.0 V to 5.5 V |
| Operating Temperature | -40°C to +85°C |
| Package | 8-pin Wide-Body SOIC |
| Creepage | 5.5 mm |
| ESD Protection (HBM, bus pins) | ±35 kV |
| Receiver Input Impedance | 1/8 unit load |
| Drivers per Bus | Up to 256 |
| Receiver Hysteresis (typ) | 30 mV |
| Short-Circuit Protection | Yes |
| Thermal Shutdown | Yes |
| RoHS Status | Compliant |
| Mounting Type | Surface Mount |
MAX22025AWA+ Pin Configuration
| Pin 1 | VDD1 — UART-side supply voltage (3.0V to 5.5V) |
| Pin 2 | GND1 — UART-side ground (logic-side reference) |
| Pin 3 | DI — Driver input (UART TXD) |
| Pin 4 | DE — Driver enable, active-high |
| Pin 5 | RO — Receiver output (UART RXD) |
| Pin 6 | GND2 — Cable-side ground (isolated reference) |
| Pin 7 | A/B (Y/Z) — RS-485/RS-422 differential bus pins |
| Pin 8 | VDD2 — Cable-side supply (isolated output from internal DC-DC) |
Typical Applications
MAX22025AWA+ is suitable for 6 applications: Industrial PLC RS-485 Nodes, Solar Inverter Modbus Links, Battery Management System (BMS) Communication, HVAC and Building Automation Controllers, Smart-Grid Metering Data Acquisition, Fieldbus Gateway and Protocol Converters.
Industrial PLC RS-485 Nodes
The MAX22025AWA+ fits isolated RS-485 nodes in industrial PLCs because its 3.5 kVRMS isolation breaks ground loops between field wiring and the controller backplane, while the integrated isolated supply eliminates the external DC-DC typically required for power transfer. With 500 kbps headroom, it covers standard Modbus RTU at 115.2 kbps as well as faster Profibus-DP segment-master links. The 1/8 unit-load receiver allows up to 256 nodes on one trunk for dense I/O racks, and the ±35 kV HBM ESD rating survives hot-plug installation in cabinets. Place 0.1µF ceramic bypass capacitors within 2mm of each VDD pin to meet datasheet decoupling requirements.
Recommended
Solar Inverter Modbus Links
The MAX22025AWA+ suits solar inverter Modbus communication links because the 3.5 kVRMS isolation barrier withstands the large ground-potential differences between rooftop DC strings and central inverters, while the 5.5mm creepage wide-body SOIC meets IEC 60664 reinforced-insulation rules. The 500 kbps capability comfortably exceeds the 19.2 kbps and 38.4 kbps rates used for monitoring inverter telemetry. Integrated isolated power reduces the BOM by 40-60% compared to discrete optocoupler solutions, critical for compact string combiners. Operating from -40°C to +85°C handles rooftop thermal cycling.
Recommended
Battery Management System (BMS) Communication
The MAX22025AWA+ is well matched to BMS daisy-chain communication in Li-ion battery packs because its isolation protects the host microcontroller from the high-voltage battery stack, while the 1/8 unit-load input impedance allows dozens of pack monitors on one RS-485 backbone. The ±35 kV ESD rating handles the inductive switching transients of buck/boost gate drivers in the same enclosure. Compared to discrete optocouplers plus a separate isolated DC-DC, the integrated device reduces BOM and PCB area, which is critical for compact 18650/4680 pack topologies. The 500 kbps rate exceeds typical daisy-chain telemetry bandwidth.
Recommended
HVAC and Building Automation Controllers
The MAX22025AWA+ fits HVAC and building-automation RS-485 trunks because it breaks ground loops between floor-level controllers and rooftop units with large motors that generate significant common-mode noise. The 5.5mm creepage wide-body SOIC provides reinforced insulation suitable for 250V working-voltage installations. With ±35 kV ESD on the bus pins and short-circuit protected driver outputs, the part survives field-installation mishandling. Up to 256 nodes per bus supports dense sensor and actuator networks across multi-floor commercial buildings.
Recommended
Smart-Grid Metering Data Acquisition
The MAX22025AWA+ suits smart-grid metering data acquisition because its 3.5 kVRMS isolation meets utility-grade safety regulations while the integrated isolated supply simplifies compact meter form factors. The 500 kbps capability supports DLMS/COSEM and IEC 62056 DLMS protocols with extensive headroom. The 1/8 unit-load receiver allows hundreds of meters per feeder line for AMI deployments. Operating from -40°C to +85°C handles outdoor meter enclosures across continental climate zones, and the wide-body SOIC's 5.5mm creepage satisfies IEC 61010 measurement-category requirements.
Recommended
Fieldbus Gateway and Protocol Converters
The MAX22025AWA+ fits fieldbus gateway and protocol-converter designs because it bridges UART-based MCUs to industrial RS-485 networks while providing the isolation required when gateways interconnect equipment at different ground potentials. The 500 kbps data rate exceeds Modbus RTU (115.2 kbps) and Profibus-DP segment-master (12 Mbps requires MAX22027) requirements for slow-speed trunks. Replacing discrete optocouplers plus an isolated DC-DC shrinks BOM by 40-60%, enabling single-board gateway designs.
Recommended
Recommended Products Summary
Engineering reference data for MAX22025AWA+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX22025AWA+T | MAX22027AWA+ | MAX22028AWA+ | MAX22026AWA+ |
|---|---|---|---|---|---|
| Package | 8-pin Wide-Body SOIC (5.5mm creepage) | 8-pin Wide-Body SOIC - same | 8-pin Wide-Body SOIC - same | 8-pin Wide-Body SOIC - same | 8-pin Wide-Body SOIC - same |
| Brand | Analog Devices (Maxim Integrated) | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same |
| Data Rate (max) | 500 kbps | 500 kbps | 25 Mbps | 25 Mbps | 25 Mbps |
| Isolation Voltage | 3.5 kVRMS | 3.5 kVRMS | 3.5 kVRMS | 3.5 kVRMS | 3.5 kVRMS |
| Duplex | Half | Half | Half | Half | Half |
| ESD Protection (HBM, bus) | ±35 kV | ±35 kV | ±35 kV | ±35 kV | ±35 kV |
| Receiver Unit Load | 1/8 | 1/8 | 1/8 | 1/8 | 1/8 |
| AutoDirection | No | No | No | Yes | No |
| Operating Temperature | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C |
Key Differentiators
- Integrated isolated power supply - no external DC-DC needed (vs MAX14882AWE+)
- Highest-in-class ESD rating of ±35 kV HBM on bus pins (vs MAX22027AWA+)
- 1/8 unit-load receiver enables 256-node multi-drop buses (vs Legacy 1/8 unit-load competitors)
- Wide-body SOIC with 5.5mm creepage meets IEC 60664 reinforced insulation (vs Narrow-body SOIC isolated transceivers)
Design Notes
Place 0.1µF ceramic bypass capacitors within 2mm of each VDD pin (pins 1 and 8) to meet the datasheet decoupling requirement. The wide-body SOIC's 5.5mm creepage must be preserved on the PCB - avoid running any copper traces under the package body between GND1 and GND2, since this reduces the effective isolation barrier. Add a ground plane on each side of the device, but do NOT bridge the two ground planes outside the IC.
Do not tie DE high and expect full-duplex operation - the MAX22025AWA+ is half-duplex and shares a single differential pair for transmit and receive. If full-duplex is required, switch to the MAX14850ASE+ family which uses separate TX and RX differential pairs. Also note that the cable-side ground (GND2, pin 6) is internally isolated from GND1; connecting them externally defeats the isolation barrier.
Terminate the RS-485 bus with a 120Ω resistor between A and B at each end of the trunk to suppress reflections on long cable runs. For stubs longer than 100mm, use a 1kΩ pull-up on A and 1kΩ pull-down on B at the device pins to bias the bus into the idle-high state. The MAX22025AWA+ internal receiver deglitch filters spikes up to 150ns, so no external TVS is required for typical industrial transients.
Estimated: at 500 kbps with a 54Ω differential load, the MAX22025AWA+ dissipates approximately 150 mW from its VDD1 supply, plus another 50 mW on the cable-side. The 8-pin wide-body SOIC has theta_JA of approximately 110°C/W on a 4-layer JEDEC board, giving a junction temperature rise of 22°C above ambient. This is well within the -40°C to +85°C operating range, so no heatsink is required.
Compliance Information
RoHS and REACH compliant per Analog Devices product page. Lead-free, MSL Level 1, IEC 60664-1 reinforced insulation compliant via 5.5mm creepage wide-body SOIC. Not AEC-Q100 qualified - this part targets industrial-grade applications.
