SCPS274B June   2021  – March 2023 TCA39306

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 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
      1. 8.1.1 Definition of threshold voltage
      2. 8.1.2 Correct Device Set Up
      3. 8.1.3 Disconnecting a Responder from the Main Bus Using the EN Pin
      4. 8.1.4 Supporting Remote Board Insertion to Backplane with TCA39306
      5. 8.1.5 Switch Configuration
      6. 8.1.6 Controller on Side 1 or Side 2 of Device
      7. 8.1.7 LDO and TCA39306 Concerns
      8. 8.1.8 Current Limiting Resistance on VREF2
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Enable (EN) Pin
      2. 8.3.2 Voltage Translation
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 General Applications of I2C
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Bidirectional Voltage Translation
        2. 9.2.2.2 Sizing Pullup Resistors
        3. 9.2.2.3 Bandwidth
      3. 9.2.3 Application Curve
    3. 9.3 Systems Examples: I3C Usage Considerations
      1. 9.3.1 I3C Bus Switching
      2. 9.3.2 I3C Bus Voltage Translation
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

9.2.2.3 Bandwidth

The maximum frequency of the device depends on the application. The device can operate at speeds of > 100 MHz given the correct conditions. The maximum frequency is dependent upon the loading of the application.

However, this is an analog type of measurement. For digital applications, the signal should not degrade up to the fifth harmonic of the digital signal. The frequency bandwidth should be at least five times the maximum digital clock rate. This component of the signal is important in determining the overall shape of the digital signal. In the case of the device, digital clock frequency of >100 MHz can be achieved.

The device does not provide any drive capability like the TCA9517 or other buffered translators. Therefore, higher-frequency applications require higher drive strength from the host side. No pullup resistor is needed on the host side (3.3 V) if the device is being driven by standard CMOS push-pull output driver. Ideally, it is best to minimize the trace length from device on the sink side (1.8 V) to minimize signal degradation.

You can then use a simple formula to compute the maximum practical frequency component or the knee frequency (fknee). All fast edges have an infinite spectrum of frequency components. However, there is an inflection (or knee) in the frequency spectrum of fast edges where frequency components higher than fknee are insignificant in determining the shape of the signal.

To calculate fknee:

Equation 7. fknee = 0.5 / RT (10%–90%)
Equation 8. fknee = 0.4 / RT (20%–80%)

For signals with rise-time characteristics based on 10- to 90-percent thresholds, fknee is equal to 0.5 divided by the rise time of the signal. For signals with rise-time characteristics based on 20- to 80-percent thresholds, which is very common in many current device specifications, fknee is equal to 0.4 divided by the rise time of the signal.

Some guidelines to follow that help maximize the performance of the device:

  • Keep trace length to a minimum by placing the device close to the I2C output of the processor.
  • The trace length should be less than half the time of flight to reduce ringing and line reflections or non-monotonic behavior in the switching region.
  • To reduce overshoots, a pullup resistor can be added on the 1.8 V side; be aware that a slower fall time is to be expected.