1. Products
  2. Interface and Isolation
  3. RS-232 / RS-422 / RS-485 / RS-562
  4. RS-485 and RS-422
  5. LT1791

Data Sheet Rev. E
JP
User Guides Rev. A
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IBIS Models
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Overview

Features and Benefits

  • Protected from Overvoltage Line Faults to ±60V
  • Pin Compatible with LTC485 and LTC491
  • High Input Impedance Supports Up to 128 Nodes
  • No Damage or Latchup to ESD
    • IEC-1000-4-2 Level 4: ±15kV Air Discharge
    • IEC-1000-4-2 Level 2: ±4kV Contact Discharge
  • Controlled Slew Rates for EMI Emissions Control
  • Guaranteed High Receiver Output State for Floating, Shorted or Inactive Inputs (LT1785A/LT1791A)
  • Outputs Assume a High Impedance When Off or Powered Down
  • Drives Low Cost, Low Impedance Cables
  • Short-Circuit Protection on All Outputs
  • Thermal Shutdown Protection
  • Guaranteed Operation to 125°C
  • AEC-Q100 Qualified for Automotive Applications (LT1785#W)

Product Details

The LT1785/LT1791 are half-duplex and full-duplex differential bus transceivers for RS485 and RS422 applications which feature on-chip protection from overvoltage faults on the data transmission lines. Receiver input and driver output pins can withstand voltage faults up to ±60V with respect to ground with no damage to the device. Faults may occur while the transceiver is active, shut down or powered off.

Data rates to 250kbaud on networks of up to 128 nodes are supported. Controlled slew rates on the driver outputs control EMI emissions and improve data transmission integrity on improperly terminated lines. Drivers are specified to operate with inexpensive cables as low as 72Ω characteristic impedance.

The LT1785A/LT1791A devices have “fail-safe” receiver inputs to guarantee a receiver output high for shorted, open or inactive data lines. On-chip ESD protection eliminates need for external protection devices.

The LT1785/LT1785A are available in 8-lead DIP and SO packages and the LT1791/LT1791A in 14-lead DIP and SO packages.

Applications

  • Industrial Control Data Networks
  • CAN Bus Applications
  • HVAC Controls

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At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

Documentation & Resources

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  • Data Sheets (1)
  • Reliability Data (1)
  • User Guides (1)
  • Design Notes (1)
  • Product Selector Card (2)
  • Product Selection Guide (1)
  • Videos (1)
  • Technical Articles (2)
    • Document Type

    Tools & Simulations

    IBIS Models

    Product Recommendations

    LT1791 Companion Parts

    Recommended Related Parts

    Design Resources

    ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

    Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
    LT1791ACN#PBF Material Declaration Reliability Data 14-Lead PDIP (Narrow 0.3 Inch)
    LT1791ACS#PBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791ACS#TRPBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791AHN#PBF Material Declaration Reliability Data 14-Lead PDIP (Narrow 0.3 Inch)
    LT1791AHS#PBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791AHS#TRPBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791AIN#PBF Material Declaration Reliability Data 14-Lead PDIP (Narrow 0.3 Inch)
    LT1791AIS#PBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791AIS#TRPBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791CN#PBF Material Declaration Reliability Data 14-Lead PDIP (Narrow 0.3 Inch)
    LT1791CS#PBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791CS#TRPBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791HN#PBF Material Declaration Reliability Data 14-Lead PDIP (Narrow 0.3 Inch)
    LT1791HS#PBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791HS#TRPBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791IN#PBF Material Declaration Reliability Data 14-Lead PDIP (Narrow 0.3 Inch)
    LT1791IS#PBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    LT1791IS#TRPBF Material Declaration Reliability Data 14-Lead SOIC (Narrow 0.15 Inch)
    Wafer Fabrication Data R001 Reliability Data

    PCN-PDN Information

    Select a model from the dropdown below to subscribe to PCN/PDN notifications and view past notifications as well.

    Select Model for PCN Information
    • LT1791ACN#PBF Production
    • LT1791ACS#PBF Production
    • LT1791ACS#TRPBF Production
    • LT1791AHN#PBF Production
    • LT1791AHS#PBF Production
    • LT1791AHS#TRPBF Production
    • LT1791AIN#PBF Production
    • LT1791AIS#PBF Production
    • LT1791AIS#TRPBF Production
    • LT1791CN#PBF Production
    • LT1791CS#PBF Production
    • LT1791CS#TRPBF Production
    • LT1791HN#PBF Production
    • LT1791HS#PBF Production
    • LT1791HS#TRPBF Production
    • LT1791IN#PBF Production
    • LT1791IS#PBF Production
    • LT1791IS#TRPBF Production

    Support & Discussions

    LT1791 Discussions

    SPICE model for LTC490 (differential driver and receiver pair)
    All LT1791 Discussions
    LT1791 Contact ADI Technical Support »
    LT1791 Ask your question »
    LT1791 Contact ADI Technical Support » LT1791 Ask your question »

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