SLVSLJ5 March   2026 TCA9846

ADVANCE INFORMATION  

  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
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Electrical Characteristics
    5. 5.5 Electrical Characteristics (Global)
    6. 5.6 Thermal Information
    7. 5.7 I2C Interface Timing Requirements
    8. 5.8 Reset Timing Requirements
    9. 5.9 Switching 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
    4. 7.4 Device Functional Modes
      1. 7.4.1 RESET Input
      2. 7.4.2 Power-On Reset
    5. 7.5 Programming
      1. 7.5.1 I2C Interface
      2. 7.5.2 Device Address
      3. 7.5.3 Bus Transactions
        1. 7.5.3.1 Writes
        2. 7.5.3.2 Reads
      4. 7.5.4 Control Register
      5. 7.5.5 RESET Input
      6. 7.5.6 Power-On Reset
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Power-On Reset Requirements
    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 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1.     Package Option Addendum
    2. 11.1 Mechanical Data

封装选项

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8.2.2 Detailed Design Procedure

Once all the targets are assigned to the appropriate target channels and bus voltages are identified, the pull-up resistors, Rp, for each of the buses need to be selected appropriately. The minimum pull-up resistance is a function of VDPUX, VOL,(max), and IOL as shown in Equation 1:

Equation 1. TCA9846

The maximum pull-up resistance is a function of the maximum rise time, tr (300 ns for fast-mode operation, fSCL = 400 kHz) and bus capacitance, Cb as shown in Equation 2:

Equation 2. TCA9846

The maximum bus capacitance for an I2C bus must not exceed 400 pF for fast-mode operation. The bus capacitance can be approximated by adding the capacitance of the TCA9846, Cio(OFF), the capacitance of wires, connections and traces, and the capacitance of each individual target on a given channel. If multiple channels are activated simultaneously, each of the targets on all channels contribute to total bus capacitance.