SNAU279A July   2022  – September 2022

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2EVM Quick Start
  5. 3EVM Configuration
    1. 3.1  Power Supply
    2. 3.2  Logic Inputs and Outputs
    3. 3.3  Switching Between I2C and SPI
    4. 3.4  Generating SYSREF Request
    5. 3.5  XO Input
      1. 3.5.1 48-MHz TCXO (Default)
      2. 3.5.2 External Clock Input
      3. 3.5.3 Additional XO Input Options
      4. 3.5.4 APLL Reference Options
    6. 3.6  Reference Clock Inputs
    7. 3.7  Clock Outputs
    8. 3.8  Status Outputs and LEDs
    9. 3.9  Requirements for Making Measurements
    10. 3.10 Typical Phase Noise Characteristics
  6. 4EVM Schematics
    1. 4.1  Power Supply Schematic
    2. 4.2  Alternative Power Supply Schematic
    3. 4.3  Power Distribution Schematic
    4. 4.4  LMK5B33414 and Input Reference Inputs IN0 to IN1 Schematic
    5. 4.5  Clock Outputs OUT0 to OUT3 Schematic
    6. 4.6  Clock Outputs OUT4 to OUT9 Schematic
    7. 4.7  Clock Outputs OUT10 to OUT13 and Clock Inputs IN2 and IN3 Schematic
    8. 4.8  XO Schematic
    9. 4.9  Logic I/O Interfaces Schematic
    10. 4.10 USB2ANY Schematic
  7. 5EVM Bill of Materials
    1. 5.1 Loop Filter and Vibration Nonsensitive Capacitors
  8. 6Appendix A - TICS Pro LMK5B33414 Software
    1. 6.1  Using the Start Page
      1. 6.1.1 Step 1
      2. 6.1.2 Step 2
      3. 6.1.3 Step 3
      4. 6.1.4 Step 4
      5. 6.1.5 Step 5
      6. 6.1.6 Step 6
      7. 6.1.7 Step 7
    2. 6.2  Using the Status Page
    3. 6.3  Using the Input Page
      1. 6.3.1 Cascaded Configurations
        1. 6.3.1.1 Cascade VCO to APLL Reference
    4. 6.4  Using APLL1, APLL2, and APLL3 Pages
      1. 6.4.1 APLL DCO
    5. 6.5  Using the DPLL1, DPLL2, and DPLL3 Pages
      1. 6.5.1 DPLL DCO
    6. 6.6  Using the Validation Page
    7. 6.7  Using the GPIO Page
    8. 6.8  SYNC/SYSREF/1-PPS Page
    9. 6.9  Using the Outputs Page
    10. 6.10 EEPROM Page
    11. 6.11 Design Report Page
  9. 7Revision History

3.5 XO Input

The LMK5B33414 has an XO input (XO pin) to accept a reference clock for the Fractional-N APLLs. The XO input determines the output frequency accuracy and stability in free-run or holdover modes. For synchronization applications like SyncE or IEEE 1588, the XO input would typically be driven by a low-frequency TCXO or OCXO that conforms to the frequency accuracy and holdover stability requirements of the application. For proper DPLL operation, the XO frequency must have a non-integer frequency relationship with the VCO output frequency of any APLL that uses the XO input as its reference. The non-integer relationship should be greater than 0.05 away from an integer boundary (meaning > 0.05 and < 0.95). When configuring the LMK5B33414 as a clock generator (DPLL not used), then the XO frequency can have an integer relationship with the APLL output frequency.

The XO input of the LMK5B33414 has programmable on-chip input termination and AC-coupled input biasing options to support any clock interface type.

Figure 3-9 XO Input.