SNAS751 December   2023 LMK5C33414A

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Pin Configuration and Functions
  6. 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 Diagrams
    7. 5.7 Typical Characteristics
  7. Parameter Measurement Information
    1. 6.1 Differential Voltage Measurement Terminology
    2. 6.2 Output Clock Test Configurations
  8. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
      1. 7.2.1 PLL Architecture Overview
      2. 7.2.2 DPLL
        1. 7.2.2.1 Independent DPLL Operation
        2. 7.2.2.2 Cascaded DPLL Operation
        3. 7.2.2.3 APLL Cascaded with DPLL
      3. 7.2.3 APLL-Only Mode
    3. 7.3 Feature Description
      1. 7.3.1  Oscillator Input (XO)
      2. 7.3.2  Reference Inputs
      3. 7.3.3  Clock Input Interfacing and Termination
      4. 7.3.4  Reference Input Mux Selection
        1. 7.3.4.1 Automatic Input Selection
        2. 7.3.4.2 Manual Input Selection
      5. 7.3.5  Hitless Switching
        1. 7.3.5.1 Hitless Switching With Phase Cancellation
        2. 7.3.5.2 Hitless Switching With Phase Slew Control
        3. 7.3.5.3 Hitless Switching With 1-PPS Inputs
      6. 7.3.6  Gapped Clock Support on Reference Inputs
      7. 7.3.7  Input Clock and PLL Monitoring, Status, and Interrupts
        1. 7.3.7.1 XO Input Monitoring
        2. 7.3.7.2 Reference Input Monitoring
          1. 7.3.7.2.1 Reference Validation Timer
          2. 7.3.7.2.2 Frequency Monitoring
          3. 7.3.7.2.3 Missing Pulse Monitor (Late Detect)
          4. 7.3.7.2.4 Runt Pulse Monitor (Early Detect)
          5. 7.3.7.2.5 Phase Valid Monitor for 1-PPS Inputs
        3. 7.3.7.3 PLL Lock Detectors
        4. 7.3.7.4 Tuning Word History
        5. 7.3.7.5 Status Outputs
        6. 7.3.7.6 Interrupt
      8. 7.3.8  PLL Relationships
        1. 7.3.8.1  PLL Frequency Relationships
          1. 7.3.8.1.1 APLL Phase Detector Frequency
          2. 7.3.8.1.2 APLL VCO Frequency
          3. 7.3.8.1.3 DPLL TDC Frequency
          4. 7.3.8.1.4 DPLL VCO Frequency
          5. 7.3.8.1.5 Clock Output Frequency
        2. 7.3.8.2  Analog PLLs (APLL1, APLL2, APLL3)
        3. 7.3.8.3  APLL Reference Paths
          1. 7.3.8.3.1 APLL XO Doubler
          2. 7.3.8.3.2 APLL XO Reference (R) Divider
        4. 7.3.8.4  APLL Phase Frequency Detector (PFD) and Charge Pump
        5. 7.3.8.5  APLL Feedback Divider Paths
          1. 7.3.8.5.1 APLL N Divider With SDM
        6. 7.3.8.6  APLL Loop Filters (LF1, LF2, LF3)
        7. 7.3.8.7  APLL Voltage-Controlled Oscillators (VCO1, VCO2, VCO3)
          1. 7.3.8.7.1 VCO Calibration
        8. 7.3.8.8  APLL VCO Clock Distribution Paths
        9. 7.3.8.9  DPLL Reference (R) Divider Paths
        10. 7.3.8.10 DPLL Time-to-Digital Converter (TDC)
        11. 7.3.8.11 DPLL Loop Filter (DLF)
        12. 7.3.8.12 DPLL Feedback (FB) Divider Path
      9. 7.3.9  Output Clock Distribution
      10. 7.3.10 Output Channel Muxes
      11. 7.3.11 Output Dividers (OD)
      12. 7.3.12 SYSREF/1-PPS
      13. 7.3.13 Output Delay
      14. 7.3.14 Clock Outputs (OUTx_P/N)
        1. 7.3.14.1 Differential Output
        2. 7.3.14.2 LVCMOS Output
        3. 7.3.14.3 SYSREF/1-PPS Output Replication
        4. 7.3.14.4 Output Auto-Mute During LOL
      15. 7.3.15 Glitchless Output Clock Start-Up
      16. 7.3.16 Clock Output Interfacing and Termination
      17. 7.3.17 Output Synchronization (SYNC)
      18. 7.3.18 Zero-Delay Mode (ZDM)
      19. 7.3.19 Time Elapsed Counter (TEC)
        1. 7.3.19.1 Configuring TEC Functionality
        2. 7.3.19.2 SPI as a Trigger Source
        3. 7.3.19.3 GPIO Pin as a TEC Trigger Source
          1. 7.3.19.3.1 An Example: Making a Time Elapsed Measurement Using TEC and GPIO1 as Trigger
        4. 7.3.19.4 TEC Timing
        5. 7.3.19.5 Other TEC Behavior
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Start-Up
        1. 7.4.1.1 ROM Selection
        2. 7.4.1.2 EEPROM Overlay
      2. 7.4.2 DPLL Operating States
        1. 7.4.2.1 Free-Run
        2. 7.4.2.2 Lock Acquisition
        3. 7.4.2.3 DPLL Locked
        4. 7.4.2.4 Holdover
      3. 7.4.3 PLL Start-Up Sequence
      4. 7.4.4 Digitally-Controlled Oscillator (DCO) Frequency and Phase Adjustment
        1. 7.4.4.1 DPLL DCO Control
          1. 7.4.4.1.1 DPLL DCO Relative Adjustment Frequency Step Size
          2. 7.4.4.1.2 APLL DCO Frequency Step Size
      5. 7.4.5 APLL Frequency Control
      6. 7.4.6 DPLL Programmable Phase Delay
    5. 7.5 Programming
      1. 7.5.1 Interface and Control
      2. 7.5.2 I2C Serial Interface
        1. 7.5.2.1 I2C Block Register Transfers
      3. 7.5.3 SPI Serial Interface
        1. 7.5.3.1 SPI Block Register Transfer
      4. 7.5.4 Register Map Generation
      5. 7.5.5 General Register Programming Sequence
  9. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Device Start-Up Sequence
      2. 8.1.2 Power Down (PD#) Pin
      3. 8.1.3 Strap Pins for Start-Up
      4. 8.1.4 Pin States
      5. 8.1.5 ROM and EEPROM
      6. 8.1.6 Power Rail Sequencing, Power Supply Ramp Rate, and Mixing Supply Domains
        1. 8.1.6.1 Power-On Reset (POR) Circuit
        2. 8.1.6.2 Powering Up From a Single-Supply Rail
        3. 8.1.6.3 Power Up From Split-Supply Rails
        4. 8.1.6.4 Non-Monotonic or Slow Power-Up Supply Ramp
      7. 8.1.7 Slow or Delayed XO Start-Up
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
      1. 8.4.1 Power Supply Bypassing
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
      3. 8.5.3 Thermal Reliability
  10. Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Clock Tree Architect Programming Software
        2. 9.1.1.2 Texas Instruments Clocks and Synthesizers (TICS) Pro Software
        3. 9.1.1.3 PLLatinum™ Simulation Tool
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Glossary
    7. 9.7 Electrostatic Discharge Caution
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

APLL Cascaded with DPLL

When APLL1 and APLL2 are in cascaded mode from APLL3, VCO3 is held around its nominal center frequency of 2457.6 MHz while APLL1 and APLL2 locks. Then APLL3 locks the VCO3 frequency to the external XO input and operates in free-run mode. Cascaded PLLs lock to a divided frequency from the source VCO. When a valid DPLL reference input is detected beyond a minimum valid time, the DPLLs begin lock acquisition. Each DPLL TDC compares the phase of the selected reference input clock and the FB divider clock from the respective VCO and generates a digital correction word corresponding to the phase error. At the beginning, the DPLL TDC simply cancels out the phase error with the no filtering correction word. Then the subsequent correction word is filtered by the DLF, and the DLF output controls the APLL N divider SDM to pull the VCO frequency into lock with the reference input.

Using the VCBO as a cascade source to APLL1 or APLL2 provides the APLL a high-frequency, ultra-low-jitter reference clock. This unique cascading feature can provide improved close in phase noise performance if the XO/TCXO/OCXO is a low frequency or has poor phase noise performance. Note that in cascaded DPLL operation the best jitter performance and frequency stability will be achieved after DPLL3 locked.

DPLL3 lock status will impact DPLL1 and DPLL2 lock status. If APLL3 is in free-run mode or holdover mode, the VCBO frequency offset ppm value could introduce a similar frequency offset at APLL1 and APLL2 outputs even though DPLL1 and DPLL2 can stay in locked status. In this configuration example,TI recommends to monitor the lock status of PLL3 along with PLL2 or PLL1. Alternatively at start-up, ensure that the DPLL3 and APLL3 are locked first, then toggle the PLL1 or PLL2 enable cycle (APLLx_EN bit = 0 → 1) to calibrate VCO1 or VCO2, and then double check the PLL1 or PLL2 lock status.

In above example, APLL3 is upstream PLL, while APLL1 and APLL2 are downstream PLLs. If there are system start-up requirements on the clock sequencing, APLL1 or APLL2 also can be configured as the upstream PLL.

When cascading PLLs, the downstream APLL may use the DPLL or bypass and power down the DPLL depending on performance requirements. If DPLL1 and DPLL2 are disabled from above APLL cascaded mode, then DPLL3-only cascade mode may be used. In this case, VCO1 or VCO2 can track the VCO3 domain during DPLL3 lock acquisition and locked modes, which allows the user to synchronize the clock domain of the APLL1 or APLL2 to the DPLL3 reference input.

When a DPLL is disabled, TI recommends to use the 24-bit numerator and programmable 24-bit denominator instead of the fixed 40-bit denominator to eliminate frequency error from APLL reference to output.

Do not cascade one VCO output to both the DPLL reference and APLL reference of the same DPLL/APLL pair.

GUID-31A9F44D-CAC5-43D2-8D2D-CE4A8CDFEE26-low.svgFigure 7-5 APLL Cascaded with DPLLs Enabled Example
GUID-D94A344B-E12B-4CC9-B175-931A862141D1-low.svgFigure 7-6 APLL Cascaded with DPLLs Disabled Example