ZHCSUH0G August   2007  – January 2024 CDCE949 , CDCEL949

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  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 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 EEPROM Specification
    7. 5.7 Timing Requirements: CLK_IN
    8. 5.8 Timing Requirements: SDA/SCL
    9. 5.9 Typical 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
      1. 7.3.1 Control Terminal Setting
      2. 7.3.2 Default Device Setting
      3. 7.3.3 SDA/SCL Serial Interface
      4. 7.3.4 Data Protocol
    4. 7.4 Device Functional Modes
      1. 7.4.1 SDA/SCL Hardware Interface
    5. 7.5 Programming
  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
        1. 8.2.2.1 Spread Spectrum Clock (SSC)
        2. 8.2.2.2 PLL Frequency Planning
        3. 8.2.2.3 Crystal Oscillator Start-Up
        4. 8.2.2.4 Frequency Adjustment With Crystal Oscillator Pulling
        5. 8.2.2.5 Unused Inputs and Outputs
        6. 8.2.2.6 Switching Between XO and VCXO Mode
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Register Maps
    1. 9.1 SDA/SCL Configuration Registers
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
    2. 10.2 Related Documentation
    3. 10.3 Related Links
    4. 10.4 接收文档更新通知
    5. 10.5 支持资源
    6. 10.6 Trademarks
    7. 10.7 静电放电警告
    8. 10.8 术语表
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

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7.4.1 SDA/SCL Hardware Interface

Figure 7-3 shows how the CDCEx949 clock synthesizer is connected to the SDA/SCL serial interface bus. Multiple devices can be connected to the bus but the speed may need to be reduced (400 kHz is the maximum) if many devices are connected.

Note that the pullup resistor value (RP) depends on the supply voltage, bus capacitance and number of connected devices. The recommended pullup value is 4.7 kΩ. The value must meet the minimum sink current of 3 mA at VOLmax = 0.4 V for the output stages (for more details, see SMBus or I2C Bus specification).

GUID-B8AC84F0-C3A4-4152-B38B-72A347B17A57-low.svg Figure 7-3 SDA/SCL Hardware Interface