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

9.1.1 Driver Amplitude Adjust

The SN65HVD64 device can provide up to 2.5 V of peak-to-peak output signal at the TXOUT pin to compensate for potential loss within the external filter, cable, connections, and termination. External resistors are used to set the amplitude of the modulated driver output signal. Resistors connected across RES and BIAS set the output amplitude. The maximum peak-to-peak voltage at TXOUT is 2.5 V, corresponding to 6 dBm on the coaxial cable. The TXOUT voltage level can be adjusted by choice of resistors to set the voltage at the RES pin according to Equation 1:

Equation 1. VTXOUT (VPP) = (2.5 VPP × VRES (V)) / 1.5 V VRES (V) = 1.5 V × R2 / (R1 + R2) VTXOUT (VPP) = 2.5 VPP × R2 / (R1 + R2)

The voltage at the RES pin should be from 0.7 V to 1.5 V. Connect RES directly to the BIAS (R1 = 0 Ω) for maximum output level of 2.5 VPP. This gives a minimum voltage level at TXOUT of 1.2 VPP, corresponding to about 0 dBm at the coaxial cable. A 1-μF capacitor should be connected between the BIAS pin and GND. To obtain a nominal power level of 3 dBm at the feeder cable as the AISG standard requires, use R1 = 4.1 kΩ and R2 = 10 kΩ that provide 1.78 VPP at TXOUT.