SLOA101B August   2002  – May 2016 SN55HVD233-SEP , SN65HVDA1040A-Q1 , SN65HVDA1050A-Q1 , SN65HVDA540-5-Q1 , SN65HVDA540-Q1 , SN65HVDA541-5-Q1 , SN65HVDA541-Q1 , SN65HVDA542-5-Q1 , SN65HVDA542-Q1

 

  1.   Introduction to the Controller Area Network (CAN)
    1.     Trademarks
    2. 1 Introduction
    3. 2 The CAN Standard
    4. 3 Standard CAN or Extended CAN
      1. 3.1 The Bit Fields of Standard CAN and Extended CAN
        1. 3.1.1 Standard CAN
        2. 3.1.2 Extended CAN
    5. 4 A CAN Message
      1. 4.1 Arbitration
      2. 4.2 Message Types
        1. 4.2.1 The Data Frame
        2. 4.2.2 The Remote Frame
        3. 4.2.3 The Error Frame
        4. 4.2.4 The Overload Frame
      3. 4.3 A Valid Frame
      4. 4.4 Error Checking and Fault Confinement
    6. 5 The CAN Bus
      1. 5.1 CAN Transceiver Features
        1. 5.1.1  3.3-V Supply Voltage
        2. 5.1.2  ESD Protection
        3. 5.1.3  Common-Mode Voltage Operating Range
        4. 5.1.4  Common-Mode Noise Rejection
        5. 5.1.5  Controlled Driver Output Transition Times
        6. 5.1.6  Low-Current Bus Monitor, Standby and Sleep Modes
        7. 5.1.7  Bus Pin Short-Circuit Protection
        8. 5.1.8  Thermal Shutdown Protection
        9. 5.1.9  Bus Input Impedance
        10. 5.1.10 Glitch-Free Power Up and Power Down
        11. 5.1.11 Unpowered Node Protection
        12. 5.1.12 Reference Voltage
        13. 5.1.13 V-Split
        14. 5.1.14 Loopback
        15. 5.1.15 Autobaud Loopback
      2. 5.2 CAN Transceiver Selection Guide
    7. 6 Conclusion
    8. 7 Additional Reading
  2.   Revision History

5.1.4 Common-Mode Noise Rejection

Common-mode noise of varied magnitudes exist within the networks associated with CAN applications. Noise from pulsing motor controllers, switch-mode power supplies, or from fluorescent lighting load are the typical sources of noises that couple onto bus lines as displayed in Figure 11. These would otherwise be straight lines.

twstpr_loa101.gifFigure 11. Common-Mode Noise Coupled Onto Four Twisted-Pair Bus Lines

A CAN transceiver's receiver not specifically designed to reject this coupled noise can respond to common-mode noise as if it were data on a bus and send meaningless data to a controller. TI CAN transceivers are specifically designed and tested for their ability to reject this common-mode noise.