Top

Compact, Isolated, Half-Duplex RS-485/RS-422 Transceivers with AutoDirection Control

Tiny, Isolated RS-485/RS-422 Transceiver

Product Details

The MAX22025–MAX22028/MAX22025F–MAX22028F compact isolated RS-485/ RS-422 transceivers provide 3.5kVRMS of digital galvanic isolation between the cable-side (RS-485/RS-422 driver/ receiver-side) and the UART-side of the device. Isolation improves communication by breaking ground loops and reduces noise when there are large differences in ground potential between ports. These devices allow for robust communication up to 0.5Mbps or 16Mbps.

The MAX22025–MAX22028/MAX22025F–MAX22028F feature Maxim’s proprietary AutoDirection control making these devices ideal for applications such as isolated RS-485 ports, where the driver input is used in conjuction with the driver-enable signal to drive the differential bus.

The MAX22025/MAX22027/MAX22025F/MAX22027F feature reduced slew rate drivers that minimize EMI and reduce reflections caused by improper termination of cable allowing error-free transmission up to 0.5Mbps. The MAX22026/MAX22028/MAX22026F/MAX22028F driver outputs are not slew-rate limited, allowing transmit speeds up to 16Mbps.

The receiver output of the MAX22025/MAX22026/MAX22025F/MAX22026F does not follow (VA-VB) when the device is in the driverenabled state. The receiver output on the MAX22027/MAX22028/MAX22027F/ MAX22028F always follows (VA-VB).

The driver outputs and receiver inputs are protected from ±10kV electrostatic discharge (ESD) to GNDB on the cable side, as specified by the Human Body Model (HBM). The MAX22025–MAX22028/MAX22025F–MAX22028F are available in a compact 8-pin wide body SOIC package and operate over the -40°C to +85°C temperature range.

Key Features

  • High-Level Integration Reduces Overall Solution Size
    • Fully Isolated Half-Duplex RS-485/RS-422 Transceivers
    • Compact 8-Pin Wide Body SOIC Package (5.5mm Creepage)
  • Integrated Protection Ensures Robust Communication
    • ±10kV ESD (HBM) on Driver Outputs/Receiver Inputs
    • Failsafe Receiver Prevents Fault Transition on Receiver Input Short or Open Events (MAX22025F– MAX22028F)
    • Withstands 3.5kVRMS Isolation Voltage for 60 Seconds (VISO)
    • Withstands 630VPEAK Maximum Repetitive Peak- Isolation Voltage (VIORM)
    • Continuously Withstands 445VRMS Maximum Working-Isolation Voltage (VIOWM)
  • Enables Flexible System Design
    • 0.5Mbps Maximum Data Rate with Slew-Rate Limited Driver (MAX22025/MAX22027/MAX22025F/MAX22027F)
    • 16Mbps Maximum Data Rate ((MAX22026/MAX22028/MAX22026F/MAX22028F)
    • AutoDirection Eliminates the Need for DE and Active-Low RE Control Signals

Applications/Uses

  • Utility Meters
  • Industrial Automation Equipment
  • Programmable Logic Controllers
  • HVAC
Parametric specs for RS-485/RS-422 Transceivers (RS485, RS422 TxRx)
# Tx/Rx 1Tx + 1Rx
Duplex -
VSUPPLY (V) -
Data Rate (kbps) (min) 500
Galvanic Isolation (±V) 3500
ESD Protect. (±kV) 10
Tx EN -
Rx EN -
Oper. Temp. (°C) -40 to +85
Package/Pins SOIC (W)/8
Budgetary
Price (See Notes)
$1.75 @1k
View More

Simplified Block Diagram

MAX22025, MAX22025F, MAX22026, MAX22026F, MAX22027, MAX22027F, MAX22028, MAX22028F: Functional Diagram MAX22025, MAX22025F, MAX22026, MAX22026F, MAX22027, MAX22027F, MAX22028, MAX22028F: Typical Operating Circuit Zoom icon

Technical Docs

Design & Development

Click any title below to view the detail page where available.

Description

The MAX2202XEVKIT# evaluation kit (EV kit) is a fully assembled and tested PCB that demonstrates the functionality of the MAX22028 isolated RS-485 transceiver with AutoDirection. The EV kit operates from a single 3.3V supply and features an on-board isolated power supply to power the secondary side of the circuit.

The MAX2202X EV kit ships with the MAX22028 installed. The board can also be used to evaluate the MAX22025– MAX22027 and the MAX22025F–MAX22028F.

View Details

Features

  • Operates from a Single 3.3V Supply
  • Terminal Block Connector for Easy RS-485 Evaluation
  • 3500VRMS Isolation for 60s
  • Fully Assembled and Tested

/en/design/design-tools/ee-sim.html?

SIMULATION MODELS

MAX22025F IBIS Model

Download

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal.

Parameters

Parametric specs for RS-485/RS-422 Transceivers (RS485, RS422 TxRx)
# Tx/Rx 1Tx + 1Rx
Duplex -
VSUPPLY (V) -
Data Rate (kbps) (min) 500
Galvanic Isolation (±V) 3500
ESD Protect. (±kV) 10
Tx EN -
Rx EN -
Oper. Temp. (°C) -40 to +85
Package/Pins SOIC (W)/8
Budgetary
Price (See Notes)
$1.75 @1k

Key Features

  • High-Level Integration Reduces Overall Solution Size
    • Fully Isolated Half-Duplex RS-485/RS-422 Transceivers
    • Compact 8-Pin Wide Body SOIC Package (5.5mm Creepage)
  • Integrated Protection Ensures Robust Communication
    • ±10kV ESD (HBM) on Driver Outputs/Receiver Inputs
    • Failsafe Receiver Prevents Fault Transition on Receiver Input Short or Open Events (MAX22025F– MAX22028F)
    • Withstands 3.5kVRMS Isolation Voltage for 60 Seconds (VISO)
    • Withstands 630VPEAK Maximum Repetitive Peak- Isolation Voltage (VIORM)
    • Continuously Withstands 445VRMS Maximum Working-Isolation Voltage (VIOWM)
  • Enables Flexible System Design
    • 0.5Mbps Maximum Data Rate with Slew-Rate Limited Driver (MAX22025/MAX22027/MAX22025F/MAX22027F)
    • 16Mbps Maximum Data Rate ((MAX22026/MAX22028/MAX22026F/MAX22028F)
    • AutoDirection Eliminates the Need for DE and Active-Low RE Control Signals

Applications/Uses

  • Utility Meters
  • Industrial Automation Equipment
  • Programmable Logic Controllers
  • HVAC

Description

The MAX22025–MAX22028/MAX22025F–MAX22028F compact isolated RS-485/ RS-422 transceivers provide 3.5kVRMS of digital galvanic isolation between the cable-side (RS-485/RS-422 driver/ receiver-side) and the UART-side of the device. Isolation improves communication by breaking ground loops and reduces noise when there are large differences in ground potential between ports. These devices allow for robust communication up to 0.5Mbps or 16Mbps.

The MAX22025–MAX22028/MAX22025F–MAX22028F feature Maxim’s proprietary AutoDirection control making these devices ideal for applications such as isolated RS-485 ports, where the driver input is used in conjuction with the driver-enable signal to drive the differential bus.

The MAX22025/MAX22027/MAX22025F/MAX22027F feature reduced slew rate drivers that minimize EMI and reduce reflections caused by improper termination of cable allowing error-free transmission up to 0.5Mbps. The MAX22026/MAX22028/MAX22026F/MAX22028F driver outputs are not slew-rate limited, allowing transmit speeds up to 16Mbps.

The receiver output of the MAX22025/MAX22026/MAX22025F/MAX22026F does not follow (VA-VB) when the device is in the driverenabled state. The receiver output on the MAX22027/MAX22028/MAX22027F/ MAX22028F always follows (VA-VB).

The driver outputs and receiver inputs are protected from ±10kV electrostatic discharge (ESD) to GNDB on the cable side, as specified by the Human Body Model (HBM). The MAX22025–MAX22028/MAX22025F–MAX22028F are available in a compact 8-pin wide body SOIC package and operate over the -40°C to +85°C temperature range.

Simplified Block Diagram

MAX22025, MAX22025F, MAX22026, MAX22026F, MAX22027, MAX22027F, MAX22028, MAX22028F: Functional Diagram MAX22025, MAX22025F, MAX22026, MAX22026F, MAX22027, MAX22027F, MAX22028, MAX22028F: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal.