SLAS564I August   2007  – December 2024 CDCE937 , CDCEL937

PRODUCTION DATA  

  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 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements: CLK_IN
    7. 5.7 Timing Requirements: SDA/SCL
    8. 5.8 EEPROM Specification
    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 Register Maps
    1. 8.1 SDA/SCL Configuration Registers
  10. 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
        1. 9.2.2.1 Spread Spectrum Clock (SSC)
        2. 9.2.2.2 PLL Frequency Planning
        3. 9.2.2.3 Crystal Oscillator Start-Up
        4. 9.2.2.4 Frequency Adjustment With Crystal Oscillator Pulling
        5. 9.2.2.5 Unused Inputs and Outputs
        6. 9.2.2.6 Switching Between XO and VCXO Mode
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

7.4.1 SDA/SCL Hardware Interface

Figure 7-3 shows how the CDCEx937 clock synthesizer is connected to the SDA/SCL serial interface bus. Multiple devices can be connected to the bus but the speed can require reduction (400kHz is the maximum) if many devices are connected.

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

CDCE937 CDCEL937 SDA/SCL Hardware InterfaceFigure 7-3 SDA/SCL Hardware Interface