Features

• UL Rated Isolated RS485: 2500V_RMS
  UL Recognized ® File #E151738
• Eliminates Ground Loops
• 250kBd Maximum Data Rate
• Self-Powered with 420kHz Converter
• Half- or Full-Duplex
• Fail-Safe Output High for Open or Shorted Receiver Inputs
• Short-Circuit Current Limit
• Slow Slew Rate Control
• 68kΩ Input Impedance Allows Up to 128 Nodes
• Thermal Shutdown
• 8kV ESD Protection On Driver Outputs and Receiver Inputs
• Available in 28-Lead SW Package

Typical Application

Description

The LTC®1535 is an isolated RS485 full-duplex differential line transceiver. Isolated RS485 is ideal for systems where the ground loop is broken to allow for much larger common mode voltage ranges. An internal capacitive isolation barrier provides 2500V_RMS of isolation between the line transceiver and the logic level interface. The powered side contains a 420kHz push-pull converter to power the isolated RS485 transceiver. Internal full-duplex communication occurs through the capacitive isolation barrier. The transceiver meets RS485 and RS422 requirements.

The driver and receiver feature three-state outputs, with the driver maintaining high impedance over the entire common mode range. The drivers have short-circuit current limits in both directions and a slow slew rate select to minimize EMI or reflections. The 68kΩ receiver input allows up to 128 node connections. A fail-safe feature defaults to a high output state when the receiver inputs are open or shorted.