SLLSFL9A July   2021  – December 2021 TCAN1046A-Q1

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  ESD Ratings — IEC Specifications
    4. 6.4  Recommended Operating Conditions
    5. 6.5  Thermal Characteristics
    6. 6.6  Supply Characteristics
    7. 6.7  Dissipation Ratings
    8. 6.8  Electrical Characteristics
    9. 6.9  Switching Characteristics
    10. 6.10 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 Pin Description
        1. 8.3.1.1 TXD1 and TXD2
        2. 8.3.1.2 GND1 and GND2
        3. 8.3.1.3 VCC1 and VCC2
        4. 8.3.1.4 RXD1 and RXD2
        5. 8.3.1.5 CANH1, CANL1, CANH2, and CANL1
        6. 8.3.1.6 STB1 and STB2 (Standby)
      2. 8.3.2 CAN Bus States
      3. 8.3.3 TXD Dominant Timeout (DTO)
      4. 8.3.4 CAN Bus Short-Circuit Current Limiting
      5. 8.3.5 Thermal Shutdown (TSD)
      6. 8.3.6 Undervoltage Lockout
      7. 8.3.7 Unpowered Device
      8. 8.3.8 Floating pins
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operating Modes
      2. 8.4.2 Normal Mode
      3. 8.4.3 Standby Mode
        1. 8.4.3.1 Remote Wake Request via Wake-Up Pattern (WUP) in Standby Mode
      4. 8.4.4 Driver and Receiver Function
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 CAN Termination
      2. 9.2.2 Detailed Design Procedures
        1. 9.2.2.1 Bus Loading, Length and Number of Nodes
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary

Package Options

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

9.2.2.1 Bus Loading, Length and Number of Nodes

A typical CAN application may have a maximum bus length of 40 meters and maximum stub length of 0.3 m. However, with careful design, users can have longer cables, longer stub lengths, and many more nodes to a bus. A high number of nodes requires a transceiver with high input impedance such as the TCAN1046A-Q1.

Many CAN organizations and standards have scaled the use of CAN for applications outside the original ISO 11898-2 standard. They made system-level trade off decisions for data rate, cable length, and parasitic loading of the bus. Examples of these CAN systems-level specifications are ARINC 825, CANopen, DeviceNet, SAE J2284, SAE J1939, and NMEA 2000.

A CAN network system design is a series of tradeoffs. In the ISO 11898-2:2016 specification the driver differential output is specified with a bus load that can range from 50 Ω to 65 Ω where the differential output must be greater than 1.5 V. The TCAN1046A-Q1 is specified to meet the 1.5-V requirement down to 50 Ω and is specified to meet 1.4-V differential output at 45Ω bus load. The differential input resistance of the TCAN1046A-Q1 is a minimum of 40 kΩ. If 100 TCAN1046A-Q1 transceivers are in parallel on a bus, this is equivalent to a 400-Ω differential load in parallel with the nominal 60 Ω bus termination which gives a total bus load of approximately 52 Ω. Therefore, the TCAN1046A-Q1 theoretically supports over 100 transceivers on a single bus segment. However, for a CAN network design margin must be given for signal loss across the system and cabling, parasitic loadings, timing, network imbalances, ground offsets and signal integrity; thus, a practical maximum number of nodes is often lower. Bus length may also be extended beyond 40 meters by careful system design and data rate tradeoffs. For example, CANopen network design guidelines allow the network to be up to 1 km with changes in the termination resistance, cabling, less than 64 nodes and significantly lowered data rate.

This flexibility in CAN network design is one of the key strengths of the various extensions and additional standards that have been built on the original ISO 11898-2 CAN standard. However, when using this flexibility. the CAN network system must be design for robust network operation.

GUID-5402131A-A236-408E-A86D-8C350AC8F362-low.gif Figure 9-3 Typical CAN Bus