SNAS689A October   2017  – July 2019 LMK04228

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 SPI Interface Timing
    7. 7.7 Timing Diagram
  8. 8 Parameter Measurement Information
    1. 8.1 Charge Pump Current Specification Definitions
      1. 8.1.1 Charge Pump Output Current Magnitude Variation vs. Charge Pump Output Voltage
      2. 8.1.2 Charge Pump Sink Current vs. Charge Pump Output Source Current Mismatch
      3. 8.1.3 Charge Pump Output Current Magnitude Variation vs. Ambient Temperature
    2. 8.2 Differential Voltage Measurement Terminology
  9. 9 Detailed Description
    1. 9.1 Overview
      1. 9.1.1 Jitter Cleaning
      2. 9.1.2 JEDEC JESD204B Support
      3. 9.1.3 Three PLL1 Redundant Reference Inputs (CLKin0/CLKin0*, CLKin1/CLKin1*, and CLKin2/CLKin2*)
      4. 9.1.4 VCXO- and Crystal-Buffered Output
      5. 9.1.5 Frequency Holdover
      6. 9.1.6 PLL2 Integrated Loop Filter Poles
      7. 9.1.7 Internal VCOs
      8. 9.1.8 Clock Distribution
        1. 9.1.8.1 Device Clock Divider
        2. 9.1.8.2 SYSREF Clock Divider
        3. 9.1.8.3 Device Clock Delay
        4. 9.1.8.4 SYSREF Delay
        5. 9.1.8.5 Programmable Output Formats
        6. 9.1.8.6 Clock Output Synchronization
      9. 9.1.9 Status Pins
    2. 9.2 Functional Block Diagrams
    3. 9.3 Feature Description
      1. 9.3.1 SYNC/SYSREF
      2. 9.3.2 JEDEC JESD204B
        1. 9.3.2.1 How to Enable SYSREF
          1. 9.3.2.1.1 Setup of SYSREF Example
          2. 9.3.2.1.2 SYSREF_CLR
        2. 9.3.2.2 SYSREF Modes
          1. 9.3.2.2.1 SYSREF Pulser
          2. 9.3.2.2.2 Continuous SYSREF
          3. 9.3.2.2.3 SYSREF Request
      3. 9.3.3 Digital Delay
        1. 9.3.3.1 Fixed Digital Delay
          1. 9.3.3.1.1 Fixed Digital Delay Example
      4. 9.3.4 SYSREF to Device Clock Alignment
      5. 9.3.5 Input Clock Switching
        1. 9.3.5.1 Input Clock Switching - Manual Mode
        2. 9.3.5.2 Input Clock Switching - Pin Select Mode
          1. 9.3.5.2.1 Configuring Pin Select Mode
        3. 9.3.5.3 Input Clock Switching - Automatic Mode
          1. 9.3.5.3.1 Starting Active Clock
      6. 9.3.6 Digital Lock Detect
        1. 9.3.6.1 Calculating Digital Lock Detect Frequency Accuracy
      7. 9.3.7 Holdover
        1. 9.3.7.1 Enable Holdover
          1. 9.3.7.1.1 Fixed (Manual) CPout1 Holdover Mode
          2. 9.3.7.1.2 Tracked CPout1 Holdover Mode
        2. 9.3.7.2 During Holdover
        3. 9.3.7.3 Exiting Holdover
        4. 9.3.7.4 Holdover Frequency Accuracy and DAC Performance
        5. 9.3.7.5 Holdover Mode - Automatic Exit of Holdover
    4. 9.4 Programming
      1. 9.4.1 Recommended Programming Sequence
        1. 9.4.1.1 SPI LOCK
        2. 9.4.1.2 SYSREF_CLR
    5. 9.5 Register Maps
      1. 9.5.1 Register Map for Device Programming
      2. 9.5.2 Device Register Descriptions
        1. 9.5.2.1 System Functions
          1. 9.5.2.1.1 RESET, SPI_3WIRE_DIS
          2. 9.5.2.1.2 POWERDOWN
          3. 9.5.2.1.3 ID_DEVICE_TYPE
          4. 9.5.2.1.4 ID_PROD[15:8], ID_PROD
          5. 9.5.2.1.5 ID_MASKREV
          6. 9.5.2.1.6 ID_VNDR[15:8], ID_VNDR
        2. 9.5.2.2 (0x100 - 0x138) Device Clock and SYSREF Clock Output Controls
          1. 9.5.2.2.1 CLKoutX_Y_ODL, CLKoutX_Y_IDL, DCLKoutX_DIV
          2. 9.5.2.2.2 DCLKoutX_DDLY_CNTH, DCLKoutX_DDLY_CNTL
          3. 9.5.2.2.3 DCLKoutX_ADLY, DCLKoutX_ADLY_MUX, DCLKout_MUX
          4. 9.5.2.2.4 DCLKoutX_HS, SDCLKoutY_MUX, SDCLKoutY_DDLY, SDCLKoutY_HS
          5. 9.5.2.2.5 SDCLKoutY_ADLY_EN, SDCLKoutY_ADLY
          6. 9.5.2.2.6 DCLKoutX_DDLY_PD, DCLKout_ADLY_PD, DCLKoutX_Y_PD, SDCLKoutY_DIS_MODE, SDCLKoutY_PD
          7. 9.5.2.2.7 SDCLKoutY_POL, SDCLKoutY_FMT, DCLKoutX_POL, DCLKoutX_FMT
        3. 9.5.2.3 SYSREF, SYNC, and Device Config
          1. 9.5.2.3.1 VCO_MUX, OSCout_FMT
          2. 9.5.2.3.2 SYSREF_CLKin0_MUX, SYSREF_MUX
          3. 9.5.2.3.3 SYSREF_DIV[12:8], SYSREF_DIV[7:0]
          4. 9.5.2.3.4 SYSREF_DDLY[12:8], SYSREF_DDLY[7:0]
          5. 9.5.2.3.5 SYSREF_PULSE_CNT
          6. 9.5.2.3.6 PLL1_PD, VCO_LDO_PD, VCO_PD, OSCin_PD, SYSREF_GBL_PD, SYSREF_PD, SYSREF_DDLY_PD, SYSREF_PLSR_PD
          7. 9.5.2.3.7 SYSREF_CLR, SYNC_1SHOT_EN, SYNC_POL, SYNC_EN, SYNC_PLL2_DLD, SYNC_PLL1_DLD, SYNC_MODE
          8. 9.5.2.3.8 SYNC_DISSYSREF, SYNC_DISX
          9. 9.5.2.3.9 Fixed Register
        4. 9.5.2.4 (0x146 - 0x149) CLKin Control
          1. 9.5.2.4.1 CLKin2_EN, CLKin1_EN, CLKin0_EN, CLKin2_TYPE, CLKin1_TYPE, CLKin0_TYPE
          2. 9.5.2.4.2 CLKin_SEL_POL, CLKin_SEL_MODE, CLKin1_OUT_MUX, CLKin0_OUT_MUX
          3. 9.5.2.4.3 CLKin_SEL0_MUX, CLKin_SEL0_TYPE
          4. 9.5.2.4.4 SDIO_RDBK_TYPE, CLKin_SEL1_MUX, CLKin_SEL1_TYPE
        5. 9.5.2.5 RESET_MUX, RESET_TYPE
        6. 9.5.2.6 (0x14B - 0x152) Holdover
          1. 9.5.2.6.1 LOS_TIMEOUT, LOS_EN, TRACK_EN, HOLDOVER_FORCE, MAN_DAC_EN, MAN_DAC[9:8]
          2. 9.5.2.6.2 MAN_DAC[9:8], MAN_DAC[7:0]
          3. 9.5.2.6.3 DAC_TRIP_LOW
          4. 9.5.2.6.4 DAC_CLK_MULT, DAC_TRIP_HIGH
          5. 9.5.2.6.5 DAC_CLK_CNTR
          6. 9.5.2.6.6 CLKin_OVERRIDE, HOLDOVER_PLL1_DET, HOLDOVER_LOS_DET, HOLDOVER_VTUNE_DET, HOLDOVER_HITLESS_SWITCH, HOLDOVER_EN
          7. 9.5.2.6.7 HOLDOVER_DLD_CNT[13:8], HOLDOVER_DLD_CNT[7:0]
        7. 9.5.2.7 (0x153 - 0x15F) PLL1 Configuration
          1. 9.5.2.7.1 CLKin0_R[9:8], CLKin0_R[7:0]
          2. 9.5.2.7.2 CLKin1_R[9:8], CLKin1_R[7:0]
          3. 9.5.2.7.3 CLKin2_R[9:8], CLKin2_R[7:0]
          4. 9.5.2.7.4 PLL1_N
          5. 9.5.2.7.5 PLL1_WND_SIZE, PLL1_CP_TRI, PLL1_CP_POL, PLL1_CP_GAIN
          6. 9.5.2.7.6 PLL1_DLD_CNT[13:8], PLL1_DLD_CNT[7:0]
          7. 9.5.2.7.7 PLL1_LD_MUX, PLL1_LD_TYPE
        8. 9.5.2.8 (0x160 - 0x16E) PLL2 Configuration
          1. 9.5.2.8.1 PLL2_R[4:0]
          2. 9.5.2.8.2 PLL2_P, OSCin_FREQ, PLL2_XTAL_EN, PLL2_REF_2X_EN
          3. 9.5.2.8.3 PLL2_FCAL_DIS
          4. 9.5.2.8.4 PLL2_N
          5. 9.5.2.8.5 PLL2_WND_SIZE, PLL2_CP_GAIN, PLL2_CP_POL, PLL2_CP_TRI
          6. 9.5.2.8.6 SYSREF_REQ_EN, PLL2_DLD_CNT
          7. 9.5.2.8.7 PLL2_LF_R4, PLL2_LF_R3
          8. 9.5.2.8.8 PLL2_LF_C4, PLL2_LF_C3
          9. 9.5.2.8.9 PLL2_LD_MUX, PLL2_LD_TYPE
        9. 9.5.2.9 (0x16F - 0x1FFF) Misc Registers
          1. 9.5.2.9.1  Fixed Register
          2. 9.5.2.9.2  Fixed Register
          3. 9.5.2.9.3  PLL2_PRE_PD, PLL2_PD
          4. 9.5.2.9.4  OPT_REG_1
          5. 9.5.2.9.5  OPT_REG_2
          6. 9.5.2.9.6  RB_PLL1_LD_LOST, RB_PLL1_LD, CLR_PLL1_LD_LOST
          7. 9.5.2.9.7  RB_PLL2_LD_LOST, RB_PLL2_LD, CLR_PLL2_LD_LOST
          8. 9.5.2.9.8  RB_DAC_VALUE(MSB), RB_CLKinX_SEL, RB_CLKinX_LOS
          9. 9.5.2.9.9  RB_DAC_VALUE
          10. 9.5.2.9.10 RB_HOLDOVER
          11. 9.5.2.9.11 SPI_LOCK
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Digital Lock Detect Frequency Accuracy
        1. 10.1.1.1 Minimum Lock Time Calculation Example
      2. 10.1.2 Driving CLKin AND OSCin Inputs
        1. 10.1.2.1 Driving CLKin PINS With a Differential Source
        2. 10.1.2.2 Driving CLKin Pins With a Single-Ended Source
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Device Programming
    3. 10.3 Do's and Don'ts
      1. 10.3.1 Pin Connection Recommendations
  11. 11Power Supply Recommendations
    1. 11.1 Current Consumption / Power Dissipation Calculations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Thermal Management
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 TICS Pro
    2. 13.2 Community Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9.3.7.4 Holdover Frequency Accuracy and DAC Performance

When in holdover mode, PLL1 will run in open-loop and the DAC will set the CPout1 voltage. If Fixed CPout1 mode is used, then the output of the DAC will be a voltage dependant upon the MAN_DAC register. If Tracked CPout1 mode is used, then the output of the DAC will be the voltage at the CPout1 pin before holdover mode was entered. When using Tracked mode and MAN_DAC_EN = 1, during holdover the DAC value is loaded with the programmed value in MAN_DAC, not the tracked value.

When in Tracked CPout1 mode, the DAC has a worst-case tracking error of ±2 LSBs once PLL1 tuning voltage is acquired. The step size is approximately 3.2 mV, therefore the VCXO frequency error during holdover mode caused by the DAC tracking accuracy is ±6.4 mV × Kv, where Kv is the tuning sensitivity of the VCXO in use. Therefore, the accuracy of the system when in holdover mode in ppm is:

Equation 1. LMK04228 30102359.gif

Example: consider a system with a 19.2-MHz clock input, a 153.6-MHz VCXO with a Kv of 17 kHz/V. The accuracy of the system in holdover in ppm is:

Equation 2. ±0.71 ppm = ±6.4 mV × 17 kHz/V × 1e6 / 153.6 MHz

Take this frequency error into account when determining the allowable frequency error window to cause holdover mode to exit.