SLLSFI7 October   2020 SN65HVD64

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Coaxial Interface
      2. 8.3.2 Reference Input
      3. 8.3.3 RS-485 Direction Control
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Driver Amplitude Adjust
      2. 9.1.2 Direction Control
      3. 9.1.3 Direction Control Time Constant
      4. 9.1.4 Conversion Between dBm and Peak-to-Peak Voltage
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.1.2 Direction Control

In many applications the mast-top modem that receives data from the base distributes the received data through an RS-485 network to several mast-top devices. When the mast-top modem receives the first logic 0 bit (active modulated signal) it takes control of the mast-top RS-485 network by asserting the direction control signal. The duration of the direction control assertion should be optimized to pass a complete message of length B bits at the known signaling rate (1/tBIT) before relinquishing control of the mast-top RS-485 network. For example, if the messages are 10 bits in length (B=10) and the signaling rate is 9600 bits per second (tBIT = 0.104 ms) then a positive pulse of duration 1.7 ms is sufficient (with margin to allow for network propagation delays) to enable the mast-top RS-485 drivers to distribute each received message. Figure 9-1 shows the assertion of direction control.

GUID-0F5BF5BE-729F-4C5B-9DC2-F6B04703389C-low.gifFigure 9-1 Assertion of Direction Control