SCAS931G May   2012  – January 2018 CDCM6208

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information, Airflow = 0 LFM
    5. 6.5  Thermal Information, Airflow = 150 LFM
    6. 6.6  Thermal Information, Airflow = 250 LFM
    7. 6.7  Thermal Information, Airflow = 500 LFM
    8. 6.8  Single-Ended Input Characteristics (SI_MODE[1:0], SDI/SDA/PIN1, SCL/PIN4, SDO/ADD0/PIN2, SCS/ADD1/PIN3, STATUS1/PIN0, RESETN/PWR, PDN, SYNCN, REF_SEL)
    9. 6.9  Single-Ended Input Characteristics (PRI_REF, SEC_REF)
    10. 6.10 Differential Input Characteristics (PRI_REF, SEC_REF)
    11. 6.11 Crystal Input Characteristics (SEC_REF)
    12. 6.12 Single-Ended Output Characteristics (STATUS1, STATUS0, SDO, SDA)
    13. 6.13 PLL Characteristics
    14. 6.14 LVCMOS Output Characteristics
    15. 6.15 LVPECL (High-Swing CML) Output Characteristics
    16. 6.16 CML Output Characteristics
    17. 6.17 LVDS (Low-Power CML) Output Characteristics
    18. 6.18 HCSL Output Characteristics
    19. 6.19 Output Skew and Sync to Output Propagation Delay Characteristics
    20. 6.20 Device Individual Block Current Consumption
    21. 6.21 Worst Case Current Consumption
    22. 6.22 Timing Requirements, I2C Timing
    23. 6.23 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Typical Device Jitter
      2. 8.3.2  Universal Input Buffer (PRI_REF, SEC_REF)
      3. 8.3.3  VCO Calibration
      4. 8.3.4  Reference Divider (R)
      5. 8.3.5  Input Divider (M)
      6. 8.3.6  Feedback Divider (N)
      7. 8.3.7  Prescaler Dividers (PS_A, PS_B)
      8. 8.3.8  Phase Frequency Detector (PFD)
      9. 8.3.9  Charge Pump (CP)
      10. 8.3.10 Fractional Output Divider Jitter Performance
      11. 8.3.11 Device Block-Level Description
      12. 8.3.12 Device Configuration Control
      13. 8.3.13 Configuring the RESETN Pin
      14. 8.3.14 Preventing False Output Frequencies in SPI/I2C Mode at Start-Up
      15. 8.3.15 Input MUX and Smart Input MUX
    4. 8.4 Device Functional Modes
      1. 8.4.1 Control Pins Definition
      2. 8.4.2 Loop Filter Recommendations for Pin Modes
      3. 8.4.3 Status Pins Definition
      4. 8.4.4 PLL Lock Detect
      5. 8.4.5 Interface and Control
        1. 8.4.5.1 Register File Reference Convention
        2. 8.4.5.2 SPI - Serial Peripheral Interface
          1. 8.4.5.2.1 Writing to the CDCM6208
          2. 8.4.5.2.2 Reading From the CDCM6208
          3. 8.4.5.2.3 Block Write/Read Operation
          4. 8.4.5.2.4 I2C Serial Interface
    5. 8.5 Programming
    6. 8.6 Register Maps
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedures
        1. 9.2.2.1  Jitter Considerations in SERDES Systems
        2. 9.2.2.2  Jitter Considerations in ADC and DAC Systems
        3. 9.2.2.3  Configuring the PLL
        4. 9.2.2.4  Programmable Loop Filter
        5. 9.2.2.5  Loop filter Component Selection
        6. 9.2.2.6  Device Output Signaling
        7. 9.2.2.7  Integer Output Divider (IO)
        8. 9.2.2.8  Fractional Output Divider (FOD)
        9. 9.2.2.9  Output Synchronization
        10. 9.2.2.10 Output Mux on Y4 and Y5
        11. 9.2.2.11 Staggered CLK Output Power Up for Power Sequencing of a DSP
  10. 10Power Supply Recommendations
    1. 10.1 Power Rail Sequencing, Power Supply Ramp Rate, and Mixing Supply Domains
      1. 10.1.1 Mixing Supplies
      2. 10.1.2 Power-On Reset
      3. 10.1.3 Slow Power-Up Supply Ramp
      4. 10.1.4 Fast Power-Up Supply Ramp
      5. 10.1.5 Delaying VDD_Yx_Yy to Protect DSP IOs
    2. 10.2 Device Power-Up Timing
    3. 10.3 Power Down
    4. 10.4 Power Supply Ripple Rejection (PSRR) versus Ripple Frequency
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Reference Schematics
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.1 Jitter Considerations in SERDES Systems

As shown in Figure 50, the bandwidth of TX and RX is the frequency range in which clock jitter adds without any attenuation to the jitter budget of the link. Outside of these frequencies, the SERDES link will attenuate clock jitter with a 20 dB/dec or even steeper roll-off.

CDCM6208 Serial_Link_Jitter_SCAS931.gifFigure 50. Serial Link Jitter Budget Explanation

Example: SERDES link with KeyStone™ I DSP

The SERDES TX PLL of the TI KeyStone™ I DSP family (see Hardware Design Guide for KeyStone Devices (SPRABI2)) for the SRIO interface has a 13-MHz PLL bandwidth (Low Pass Characteristic, see Figure 50). The CDCM6208V2, pin-mode 27, was characterized in this example over Process, Voltage and Temperature (PVT) with a low-pass filter of 13 MHz to simulate the TX PLL. The attenuation is higher or equal to 20 dB/dec; therefore, the characterization used 20 dB/dec as worst case.

Table 41 shows the maximum total jitter over PVT with and without a low-pass filter.

Table 41. Maximum Total Jitter(1) Over PVT With and Without Low-Pass Filter

OUTPUTFREQUENCY
[MHz]		MAX TJ [ps]
DSP SPEC		MAX TJ [ps]
WITHOUT LOW-PASS FILTER		MAX TJ [ps]
WITH 13-MHZ LOW-PASS FILTER
Y0 122.88 56 9.43 8.19
Y2 30.72 56 9.60 7.36
Y3 30.72 56 9.47 7.42
Y4 156.25
(6 bit fraction)		 56 57.66 17.48
Y5 156.25
(20 bit fraction)		 56 76.87 32.32
Y6 100.00 56 86.30 33.86
Y7 66.667 300 81.71 35.77
(1) Input signal: 250-fs RMS (Integration Range 12 kHz to 5 MHz)

Figure 51 shows the maximum Total Jitter with and without low-pass filter characteristic and the maximum TI KeyStone™ I specification.

CDCM6208 Max_Jitter_cas931.pngFigure 51. Maximum Jitter Over PVT

NOTE

Due to the damping characteristic of the DSP SERDES PLLs, the actual TJ data can be worse.