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

7.3.2 Default Device Setting

The internal EEPROM of CDCEx937 is preconfigured as shown in Figure 7-1. (The input frequency is passed through to the output as a default.) This allows the device to operate in default mode without the extra production step of programming. The default setting appears after power is supplied or after power-down or power-up sequence until the settings are reprogrammed by the user to a different application configuration. A new register setting is programmed through the serial SDA/SCL Interface

CDCE937 CDCEL937 Default Device Setting Figure 7-1 Default Device Setting

Table 7-4 shows the factory default setting for the Control Terminal Register (external control pins). In normal operation, all 8 register settings are available, but in the default configuration only the first two settings (0 and 1) can be selected with S0, as S1 and S2 configured as programming pins in default mode.

Table 7-4 Factory Default Setting for Control Terminal Register(1)
Y1 PLL1 SETTINGS PLL2 SETTINGS PLL3 SETTINGS
EXTERNAL
CONTROL PINS		 OUTPUT
SELECTION		 FREQUENCY
SELECTION		 SSC
SELECTION		 OUTPUT
SELECTION		 FREQUENCY
SELECTION		 SSC
SELECTION		 OUTPUT
SELECTION		 FREQUENCY
SELECTION		 SSC
SELECTION		 OUTPUT
SELECTION
S2 S1 S0 Y1 FS1 SSC1 Y2Y3 FS2 SSC2 Y4Y5 FS3 SSC3 Y6Y7
SCL (I2C) SDA (I2C) 0 3-state fVCO1_0 off 3-state fVCO2_0 off 3-state fVCO3_0 off 3-state
SCL (I2C) SDA (I2C) 1 enabled fVCO1_0 off enabled fVCO2_0 off enabled fVCO3_0 off enabled
(1) In default mode or when programmed respectively, S1 and S2 act as serial programming interface, SDA/SCL. S1 and S2 do not have any control-pin function but S1 and S2 are internally interpreted as if S1=0 and S2=0. However, S0 is a control-pin which in the default mode switches all outputs ON or OFF (as previously predefined).