SCPS207G May   2012  – November 2019 TCA9548A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 I2C Interface Timing Requirements
    7. 6.7 Reset Timing Requirements
    8. 6.8 Switching Characteristics
    9. 6.9 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
    4. 8.4 Device Functional Modes
      1. 8.4.1 RESET Input
      2. 8.4.2 Power-On Reset
    5. 8.5 Programming
      1. 8.5.1 I2C Interface
      2. 8.5.2 Device Address
      3. 8.5.3 Bus Transactions
        1. 8.5.3.1 Writes
        2. 8.5.3.2 Reads
      4. 8.5.4 Control Register
      5. 8.5.5 RESET Input
      6. 8.5.6 Power-On Reset
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Power-On Reset Requirements
  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
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.1 Design Requirements

A typical application of the TCA9548A contains one or more data pull-up voltages, VDPUX, one for the master device (VDPUM) and one for each of the selectable slave channels (VDPU0 – VDPU7). In the event where the master device and all slave devices operate at the same voltage, then VDPUM = VDPUX = VCC. In an application where voltage translation is necessary, additional design requirements must be considered to determine an appropriate VCC voltage.

The A0, A1, and A2 pins are hardware selectable to control the slave address of the TCA9548A. These pins may be tied directly to GND or VCC in the application.

If multiple slave channels are activated simultaneously in the application, then the total IOL from SCL/SDA to GND on the master side is the sum of the currents through all pull-up resistors, Rp.

The pass-gate transistors of the TCA9548A are constructed such that the VCC voltage can be used to limit the maximum voltage that is passed from one I2C bus to another.

Figure 14 shows the voltage characteristics of the pass-gate transistors (note that the graph was generated using data specified in the Electrical Characteristics table). In order for the TCA9548A to act as a voltage translator, the Vpass voltage must be equal to or lower than the lowest bus voltage. For example, if the main bus is running at 5 V and the downstream buses are 3.3 V and 2.7 V, Vpass must be equal to or below 2.7 V to effectively clamp the downstream bus voltages. As shown in Figure 14, Vpass(max) is 2.7 V when the TCA9548A supply voltage is 4 V or lower, so the TCA9548A supply voltage could be set to 3.3 V. Pull-up resistors then can be used to bring the bus voltages to their appropriate levels (see Figure 13).