SLLSE49E September   2010  – October 2024 SN65HVD1780-Q1 , SN65HVD1781-Q1 , SN65HVD1782-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings—AEC
    3. 5.3  ESD Ratings—IEC
    4. 5.4  Recommended Operating Conditions
    5. 5.5  Thermal Information
    6. 5.6  Electrical Characteristics
    7. 5.7  Power Dissipation Ratings
    8. 5.8  Switching Characteristics
    9. 5.9  Package Dissipation Ratings
    10. 5.10 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Bus Fault Conditions
      2. 7.3.2 Receiver Failsafe
      3. 7.3.3 Hot-Plugging
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Data Rate and Bus Length
        2. 8.2.1.2 Bus Loading
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Stub Length
        2. 8.2.2.2 Receiver Failsafe
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.4 Device Functional Modes

When the driver enable pin, DE, is logic high, the differential outputs A and B follow the logic states at data input D. A logic high at D causes A to turn high and B to turn low. In this case the differential output voltage defined as VOD = VA – VB is positive. When D is low, the output states reverse, B turns high, A becomes low, and VOD is negative.

When DE is low, both outputs turn high-impedance. In this condition the logic state at D is irrelevant. The DE pin has an internal pull-down resistor to ground, thus when left open the driver is disabled (high-impedance) by default. The D pin has an internal pull-up resistor to VCC, thus, when left open while the driver is enabled, output A turns high and B turns low.

Table 7-2 Driver Function Table
INPUTENABLEOUTPUTSDRIVER STATE
DDEAB
HHHLActively drive bus High
LHLHActively drive bus Low
XLZZDriver disabled
XOPENZZDriver disabled by default
OPENHHLActively drive bus High by default

When the receiver enable pin, RE, is logic low, the receiver is enabled. When the differential input voltage defined as VID = VA – VB is positive and higher than the positive input threshold, VIT+, the receiver output, R, turns high. When VID is negative and lower than the negative input threshold, VIT–, the receiver output, R, turns low. If VID is between VIT+ and VIT– the output is indeterminate.

When RE is logic high or left open, the receiver output is high-impedance and the magnitude and polarity of VID are irrelevant. Internal biasing of the receiver inputs causes the output to go failsafe-high when the transceiver is disconnected from the bus (open-circuit), the bus lines are shorted (short-circuit), or the bus is not actively driven (idle bus).

Table 7-3 Receiver Function Table
DIFFERENTIAL INPUTENABLEOUTPUTRECEIVER STATE
VID = VA – VBRER
VID > VIT+LHReceive valid bus High
VIT– < VID < VIT+L?Indeterminate bus state
VID < VIT–LLReceive valid bus Low
XHZReceiver disabled
XOPENZReceiver disabled by default
Open-circuit busLHFail-safe high output
Short-circuit busLHFail-safe high output
Idle (terminated) busLHFail-safe high output