SNAS605AS March   2013  – May 2020 LMK04821 , LMK04826 , LMK04828

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
    1. 5.1 Device Configuration Information
  6. 6 Pin Configuration and 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 Typical Characteristics – Clock Output AC Characteristics
  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
      4. 9.1.4  VCXO/Crystal Buffered Output
      5. 9.1.5  Frequency Holdover
      6. 9.1.6  PLL2 Integrated Loop Filter Poles
      7. 9.1.7  Internal VCOs
        1. 9.1.7.1 VCO1 Divider (LMK04821 only)
      8. 9.1.8  External VCO Mode
      9. 9.1.9  Clock Distribution
        1. 9.1.9.1 Device Clock Divider
        2. 9.1.9.2 SYSREF Clock Divider
        3. 9.1.9.3 Device Clock Delay
        4. 9.1.9.4 SYSREF Delay
        5. 9.1.9.5 Glitchless Half Step and Glitchless Analog Delay
        6. 9.1.9.6 Programmable Output Formats
        7. 9.1.9.7 Clock Output Synchronization
      10. 9.1.10 Zero-Delay
      11. 9.1.11 Status Pins
    2. 9.2 Functional Block Diagram
    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
        2. 9.3.3.2 Dynamic Digital Delay
        3. 9.3.3.3 Single and Multiple Dynamic 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
        3. 9.3.5.3 Input Clock Switching - Automatic Mode
      6. 9.3.6 Digital Lock Detect
      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 Entering Holdover
        3. 9.3.7.3 During Holdover
        4. 9.3.7.4 Exiting Holdover
        5. 9.3.7.5 Holdover Frequency Accuracy and DAC Performance
        6. 9.3.7.6 Holdover Mode - Automatic Exit of Holdover
    4. 9.4 Device Functional Modes
      1. 9.4.1 Dual PLL
      2. 9.4.2 Zero-Delay Dual PLL
      3. 9.4.3 Single-Loop Mode
      4. 9.4.4 Single-Loop Mode With External VCO
      5. 9.4.5 Distribution Mode
    5. 9.5 Programming
      1. 9.5.1 Recommended Programming Sequence
        1. 9.5.1.1 SPI LOCK
        2. 9.5.1.2 SYSREF_CLR
        3. 9.5.1.3 RESET Pin
    6. 9.6 Register Maps
      1. 9.6.1 Register Map for Device Programming
    7. 9.7 Device Register Descriptions
      1. 9.7.1 System Functions
        1. 9.7.1.1 RESET, SPI_3WIRE_DIS
        2. 9.7.1.2 POWERDOWN
        3. 9.7.1.3 ID_DEVICE_TYPE
        4. 9.7.1.4 ID_PROD[15:8], ID_PROD
        5. 9.7.1.5 ID_MASKREV
        6. 9.7.1.6 ID_VNDR[15:8], ID_VNDR
      2. 9.7.2 (0x100 - 0x138) Device Clock and SYSREF Clock Output Controls
        1. 9.7.2.1 CLKoutX_Y_ODL, CLKoutX_Y_IDL, DCLKoutX_DIV
        2. 9.7.2.2 DCLKoutX_DDLY_CNTH, DCLKoutX_DDLY_CNTL
        3. 9.7.2.3 DCLKoutX_ADLY, DCLKoutX_ADLY_MUX, DCLKout_MUX
        4. 9.7.2.4 DCLKoutX_HS, SDCLKoutY_MUX, SDCLKoutY_DDLY, SDCLKoutY_HS
        5. 9.7.2.5 SDCLKoutY_ADLY_EN, SDCLKoutY_ADLY
        6. 9.7.2.6 DCLKoutX_DDLY_PD, DCLKoutX_HSg_PD, DCLKout_ADLYg_PD, DCLKout_ADLY_PD, DCLKoutX_Y_PD, SDCLKoutY_DIS_MODE, SDCLKoutY_PD
        7. 9.7.2.7 SDCLKoutY_POL, SDCLKoutY_FMT, DCLKoutX_POL, DCLKoutX_FMT
      3. 9.7.3 SYSREF, SYNC, and Device Config
        1. 9.7.3.1  VCO_MUX, OSCout_MUX, OSCout_FMT
        2. 9.7.3.2  SYSREF_CLKin0_MUX, SYSREF_MUX
        3. 9.7.3.3  SYSREF_DIV[12:8], SYSREF_DIV[7:0]
        4. 9.7.3.4  SYSREF_DDLY[12:8], SYSREF_DDLY[7:0]
        5. 9.7.3.5  SYSREF_PULSE_CNT
        6. 9.7.3.6  PLL2_NCLK_MUX, PLL1_NCLK_MUX, FB_MUX, FB_MUX_EN
        7. 9.7.3.7  PLL1_PD, VCO_LDO_PD, VCO_PD, OSCin_PD, SYSREF_GBL_PD, SYSREF_PD, SYSREF_DDLY_PD, SYSREF_PLSR_PD
        8. 9.7.3.8  DDLYdSYSREF_EN, DDLYdX_EN
        9. 9.7.3.9  DDLYd_STEP_CNT
        10. 9.7.3.10 SYSREF_CLR, SYNC_1SHOT_EN, SYNC_POL, SYNC_EN, SYNC_PLL2_DLD, SYNC_PLL1_DLD, SYNC_MODE
        11. 9.7.3.11 SYNC_DISSYSREF, SYNC_DISX
        12. 9.7.3.12 Fixed Registers (0x145, 0x171 - 0x172)
      4. 9.7.4 (0x146 - 0x149) CLKin Control
        1. 9.7.4.1 CLKin2_EN, CLKin1_EN, CLKin0_EN, CLKin2_TYPE, CLKin1_TYPE, CLKin0_TYPE
        2. 9.7.4.2 CLKin_SEL_POL, CLKin_SEL_MODE, CLKin1_OUT_MUX, CLKin0_OUT_MUX
        3. 9.7.4.3 CLKin_SEL0_MUX, CLKin_SEL0_TYPE
        4. 9.7.4.4 SDIO_RDBK_TYPE, CLKin_SEL1_MUX, CLKin_SEL1_TYPE
      5. 9.7.5 RESET_MUX, RESET_TYPE
      6. 9.7.6 (0x14B - 0x152) Holdover
        1. 9.7.6.1 LOS_TIMEOUT, LOS_EN, TRACK_EN, HOLDOVER_FORCE, MAN_DAC_EN, MAN_DAC[9:8]
        2. 9.7.6.2 MAN_DAC[9:8], MAN_DAC[7:0]
        3. 9.7.6.3 DAC_TRIP_LOW
        4. 9.7.6.4 DAC_CLK_MULT, DAC_TRIP_HIGH
        5. 9.7.6.5 DAC_CLK_CNTR
        6. 9.7.6.6 CLKin_OVERRIDE, HOLDOVER_PLL1_DET, HOLDOVER_LOS_DET, HOLDOVER_VTUNE_DET, HOLDOVER_HITLESS_SWITCH, HOLDOVER_EN
        7. 9.7.6.7 HOLDOVER_DLD_CNT[13:8], HOLDOVER_DLD_CNT[7:0]
      7. 9.7.7 (0x153 - 0x15F) PLL1 Configuration
        1. 9.7.7.1 CLKin0_R[13:8], CLKin0_R[7:0]
        2. 9.7.7.2 CLKin1_R[13:8], CLKin1_R[7:0]
        3. 9.7.7.3 CLKin2_R[13:8], CLKin2_R[7:0]
        4. 9.7.7.4 PLL1_N
        5. 9.7.7.5 PLL1_WND_SIZE, PLL1_CP_TRI, PLL1_CP_POL, PLL1_CP_GAIN
        6. 9.7.7.6 PLL1_DLD_CNT[13:8], PLL1_DLD_CNT[7:0]
        7. 9.7.7.7 PLL1_R_DLY, PLL1_N_DLY
        8. 9.7.7.8 PLL1_LD_MUX, PLL1_LD_TYPE
      8. 9.7.8 (0x160 - 0x16E) PLL2 Configuration
        1. 9.7.8.1 PLL2_R[11:8], PLL2_R[7:0]
        2. 9.7.8.2 PLL2_P, OSCin_FREQ, PLL2_XTAL_EN, PLL2_REF_2X_EN
        3. 9.7.8.3 PLL2_N_CAL
        4. 9.7.8.4 PLL2_FCAL_DIS, PLL2_N
        5. 9.7.8.5 PLL2_WND_SIZE, PLL2_CP_GAIN, PLL2_CP_POL, PLL2_CP_TRI
        6. 9.7.8.6 SYSREF_REQ_EN, PLL2_DLD_CNT
        7. 9.7.8.7 PLL2_LF_R4, PLL2_LF_R3
        8. 9.7.8.8 PLL2_LF_C4, PLL2_LF_C3
        9. 9.7.8.9 PLL2_LD_MUX, PLL2_LD_TYPE
      9. 9.7.9 (0x16F - 0x1FFF) Misc Registers
        1. 9.7.9.1  PLL2_PRE_PD, PLL2_PD
        2. 9.7.9.2  VCO1_DIV
        3. 9.7.9.3  OPT_REG_1
        4. 9.7.9.4  OPT_REG_2
        5. 9.7.9.5  RB_PLL1_LD_LOST, RB_PLL1_LD, CLR_PLL1_LD_LOST
        6. 9.7.9.6  RB_PLL2_LD_LOST, RB_PLL2_LD, CLR_PLL2_LD_LOST
        7. 9.7.9.7  RB_DAC_VALUE(MSB), RB_CLKinX_SEL, RB_CLKinX_LOS
        8. 9.7.9.8  RB_DAC_VALUE
        9. 9.7.9.9  RB_HOLDOVER
        10. 9.7.9.10 SPI_LOCK
  10. 10Applications and Implementation
    1. 10.1 Application Information
    2. 10.2 Digital Lock Detect Frequency Accuracy
      1. 10.2.1 Minimum Lock Time Calculation Example
    3. 10.3 Driving CLKin and OSCin Inputs
      1. 10.3.1 Driving CLKin and OSCin Pins With a Differential Source
      2. 10.3.2 Driving CLKin and OSCin Pins With a Single-Ended Source
    4. 10.4 Output Termination and Biasing
      1. 10.4.1 LVPECL
      2. 10.4.2 LVDS/HSDS
    5. 10.5 Typical Applications
      1. 10.5.1 Design Example
        1. 10.5.1.1 Design Requirements
        2. 10.5.1.2 Detailed Design Procedure
          1. 10.5.1.2.1 Device Configuration and Simulation - PLLatinum Sim
          2. 10.5.1.2.2 Device Programming
        3. 10.5.1.3 Application Curves
    6. 10.6 System Examples
      1. 10.6.1 System Level Diagram
    7. 10.7 Do's and Don'ts
  11. 11Power Supply Recommendations
    1. 11.1 Pin Connection Recommendations
      1. 11.1.1 VCC Pins and Decoupling
        1. 11.1.1.1 Clock Output Supplies
        2. 11.1.1.2 Low-Crosstalk Supplies
        3. 11.1.1.3 PLL2 Supplies
        4. 11.1.1.4 Clock Input Supplies
        5. 11.1.1.5 Unused Clock Inputs/Outputs
    2. 11.2 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 Development Support
        1. 13.1.1.1 PLLatinum Sim
        2. 13.1.1.2 TICS Pro
    2. 13.2 Related Links
    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

9.3.5.3 Input Clock Switching - Automatic Mode

When CLKin_SEL_MODE is 4 and LOS_EN = 1, the active clock is selected in round-robin order of enabled clock inputs, starting on an input clock switch event. The switching order of the clocks is CLKin0 → CLKin1 → CLKin2 → CLKin0, and so forth.

For a clock input to be eligible to be switched through, it must be enabled using EN_CLKinX. The LOS_TIMEOUT should also be set to a frequency below the input frequency.

To ensure LOS is valid for AC-coupled inputs, the MOS mode must be set for CLKinX and no termination is allowed to be between the pins unless DC-blocked. For example, with an LVDS differential signal into CLKin0, no 100-Ω termination should be placed directly across CLKin0 and CLKin0* pins on the IC side of the AC coupling capacitors. 100 Ω could instead be placed on the transmitter side of the AC coupling capacitors.

Starting Active Clock

When programming this mode, the currently active clock remains active if PLL1 lock detect is high. To ensure a particular clock input is the active clock when starting this mode, program CLKin_SEL_MODE to the manual mode which selects the desired clock input (CLKin0, 1, or 2). Wait for PLL1 to lock PLL1_DLD = 1, then select this mode with CLKin_SEL_MODE = 4.