SCAS891A February   2010  – May 2025 CDCE949-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Thermal Resistance Characteristics
    4. 5.4  Recommended Operating Conditions
    5. 5.5  Recommended Crystal/VCXO Specifications
    6. 5.6  EEPROM Specification
    7. 5.7  Electrical Characteristics
    8. 5.8  Timing Requirements
      1. 5.8.1 CLK_IN Timing Requirements
      2. 5.8.2 SDA/SCL Timing Requirements
    9. 5.9  Timing Diagrams
      1. 5.9.1 Timing Diagram for the SDA/SCL Serial Control Interface
    10. 5.10 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 Configuration
      2. 7.3.2 Default Device Setting
      3. 7.3.3 SDA/SCL Serial Interface
      4. 7.3.4 Data Protocol
      5. 7.3.5 PLL Multiplier/Divider Definition
    4. 7.4 Device Functional Modes
      1. 7.4.1 SDA/SCL Hardware Interface
    5. 7.5 Programming
      1. 7.5.1 Generic Programming Sequence
      2. 7.5.2 Byte Write Programming Sequence
      3. 7.5.3 Byte Read Programming Sequence
      4. 7.5.4 Block Write Programming Sequence
      5. 7.5.5 Block Read Programming Sequence
  9. 8 Register Maps
    1. 8.1 SDA and SCL Registers
    2. 8.2 Configuration Registers
      1. 8.2.1 Generic Configuration Register
      2. 8.2.2 PLL1 Configuration Register
      3. 8.2.3 PLL2 Configuration Register
      4. 8.2.4 PLL3 Configuration Register
      5. 8.2.5 PLL4 Configuration Register
  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 Performance Plots
    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 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.4 Data Protocol

The device supports Byte Write and Byte Read and Block Write and Block Read operations.

For Byte Write/Read operations, the system controller can individually access addressed bytes.

For Block Write/Read operations, the bytes are accessed in sequential order from lowest to highest byte (with most significant bit first) with the ability to stop after any complete byte has been transferred. The number of bytes read out is defined by the Byte Count field in the Generic Configuration Register. During a Block Read instruction, the entire number of bytes defined in Byte Count must be read out to correctly finish the read cycle.

When a byte is sent to the device, the byte is written into the internal register and immediately takes effect. This applies to each transferred byte, whether in a Byte Write or a Block Write sequence.

If the EEPROM write cycle is initiated, the internal registers are written into the EEPROM. Data can be read out during the programming sequence (Byte Read or Block Read). The programming status can be monitored by EEPIP, Byte 01–Bit [6]. Before beginning EEPROM programming, pull CLKIN LOW. CLKIN must be held LOW for the duration of EEPROM programming. After initiating EEPROM programming with EEWRITE, Byte 06–Bit [0], do not write to the device registers until EEPIP is read back as a 0.

The offset of the indexed byte is encoded in the command code, as described in Table 7-6.

Table 7-5 Target Receiver Address (7 bits)
DeviceA6A5A4A3A2A1(1)A0(1)R/ W
CDCE913/CDCEL91311001011/0
CDCE925/CDCEL92511001001/0
CDCE937/CDCEL93711011011/0
CDCE94911011001/0
(1) Address bits A0 and A1 are programmable via the SDA/SCL bus (Byte 01, Bit [1:0]). This allows addressing up to 4 devices connected to the same SDA/SCL bus. The least significant bit of the address byte designates a write or read operation.
Table 7-6 Command Code Definition
BIT DESCRIPTION
7 0 = Block Read or Block Write operation
1 = Byte Read or Byte Write operation
(6:0) Byte Offset for Byte Read, Block Read, Byte Write and Block Write operation.