SCPS242D December   2012  – July 2017 TCA9517

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 I2C Interface Switching Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Two-Channel Bidirectional Buffer
      2. 9.3.2 Active-High Repeater-Enable Input
      3. 9.3.3 VOL B-Side Offset Voltage
      4. 9.3.4 Standard Mode and Fast Mode Support
      5. 9.3.5 Clock Stretching Support
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Clock Stretching Support
        2. 10.2.2.2 VILC and Pullup Resistor Sizing
      3. 10.2.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Community Resource
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9 Detailed Description

9.1 Overview

The TCA9517 is a bidirectional buffer with level shifting capabilities for I2C and SMBus systems. It provides bidirectional voltage-level translation (up-translation/down-translation) between low voltages (down to 0.9 V) and higher voltages (2.7 V to 5.5 V) in mixed-mode applications. This device enables I2C and SMBus systems to be extended without degradation of performance, even during level shifting.

The TCA9517 buffers both the serial data (SDA) and the serial clock (SCL) signals on the I2C bus, thus allowing two buses of up to 400-pF bus capacitance to be connected in an I2C application.

The TCA9517 has two types of drivers: A-side drivers and B-side drivers. All inputs and I/Os are over-voltage tolerant to 5.5 V, even when the device is unpowered (VCCB and/or VCCA = 0 V).

9.2 Functional Block Diagram

TCA9517 bd_cps245.gif

9.3 Feature Description

9.3.1 Two-Channel Bidirectional Buffer

The TCA9517 is a two-channel bidirectional buffer with level-shifting capabilities

9.3.2 Active-High Repeater-Enable Input

The TCA9517 has an active-high enable (EN) input with an internal pull-up to VCCB, which allows the user to select when the repeater is active. This can be used to isolate a badly behaved slave on power-up reset. The EN input should change state only when the global bus and repeater port are in an idle state, to prevent system failures.

9.3.3 VOL B-Side Offset Voltage

The B-side drivers operate from 2.7 V to 5.5 V. The output low level for this internal buffer is approximately 0.5 V, but the input voltage must be 70 mV or more below the output low level when the output internally is driven low. The higher-voltage low signal is called a buffered low. When the B-side I/O is driven low internally, the low is not recognized as a low by the input. This feature prevents a lockup condition from occurring when the input low condition is released. This type of design prevents 2 B-side ports from being connected to each other.

9.3.4 Standard Mode and Fast Mode Support

The TCA9517 supports standard mode as well as fast mode I2C. The maximum system operating frequency will depend on system design and the delays added by the repeater.

9.3.5 Clock Stretching Support

The TCA9517 can support clock stretching, but care needs to be taken to minimize the overshoot voltage presented during the hand-off between the slave and master. This is best done by increasing the pull-up resistor value.

9.4 Device Functional Modes

Table 1. Function Table

INPUT
EN		 FUNCTION
L Outputs disabled
H SDAA = SDAB
SCLA = SCLB