SNAS840 may   2023 LMK04368-EP

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Timing Diagram
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Charge Pump Current Specification Definitions
      1. 7.1.1 Charge Pump Output Current Magnitude Variation vs Charge Pump Output Voltage
      2. 7.1.2 Charge Pump Sink Current vs Charge Pump Output Source Current Mismatch
      3. 7.1.3 Charge Pump Output Current Magnitude Variation vs Ambient Temperature
    2. 7.2 Differential Voltage Measurement Terminology
  8. 8 Detailed Description
    1. 8.1 Overview
      1. 8.1.1 Differences from the LMK04832
        1. 8.1.1.1 Jitter Cleaning
        2. 8.1.1.2 JEDEC JESD204B/C Support
      2. 8.1.2 Clock Inputs
        1. 8.1.2.1 Inputs for PLL1
        2. 8.1.2.2 Inputs for PLL2
        3. 8.1.2.3 Inputs When Using Clock Distribution Mode
      3. 8.1.3 PLL1
        1. 8.1.3.1 Frequency Holdover
        2. 8.1.3.2 External VCXO for PLL1
      4. 8.1.4 PLL2
        1. 8.1.4.1 Internal VCOs for PLL2
        2. 8.1.4.2 External VCO Mode
      5. 8.1.5 Clock Distribution
        1. 8.1.5.1 Clock Divider
        2. 8.1.5.2 High Performance Divider Bypass Mode
        3. 8.1.5.3 SYSREF Clock Divider
        4. 8.1.5.4 Device Clock Delay
        5. 8.1.5.5 Dynamic Digital Delay
        6. 8.1.5.6 SYSREF Delay: Global and Local
        7. 8.1.5.7 Programmable Output Formats
        8. 8.1.5.8 Clock Output Synchronization
      6. 8.1.6 0-Delay
      7. 8.1.7 Status Pins
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Synchronizing PLL R Dividers
        1. 8.3.1.1 PLL1 R Divider Synchronization
        2. 8.3.1.2 PLL2 R Divider Synchronization
      2. 8.3.2 SYNC/SYSREF
      3. 8.3.3 JEDEC JESD204B/C
        1. 8.3.3.1 How to Enable SYSREF
          1. 8.3.3.1.1 Setup of SYSREF Example
          2. 8.3.3.1.2 SYSREF_CLR
        2. 8.3.3.2 SYSREF Modes
          1. 8.3.3.2.1 SYSREF Pulser
          2. 8.3.3.2.2 Continuous SYSREF
          3. 8.3.3.2.3 SYSREF Request
      4. 8.3.4 Digital Delay
        1. 8.3.4.1 Fixed Digital Delay
        2. 8.3.4.2 Fixed Digital Delay Example
        3. 8.3.4.3 Dynamic Digital Delay
        4. 8.3.4.4 Single and Multiple Dynamic Digital Delay Example
      5. 8.3.5 SYSREF to Device Clock Alignment
      6. 8.3.6 Input Clock Switching
        1. 8.3.6.1 Input Clock Switching - Manual Mode
        2. 8.3.6.2 Input Clock Switching - Pin Select Mode
        3. 8.3.6.3 Input Clock Switching - Automatic Mode
      7. 8.3.7 Digital Lock Detect (DLD)
        1. 8.3.7.1 Calculating Digital Lock Detect Frequency Accuracy
      8. 8.3.8 Holdover
        1. 8.3.8.1 Enable Holdover
          1. 8.3.8.1.1 Fixed (Manual) CPout1 Holdover Mode
          2. 8.3.8.1.2 Tracked CPout1 Holdover Mode
        2. 8.3.8.2 During Holdover
        3. 8.3.8.3 Exiting Holdover
        4. 8.3.8.4 Holdover Frequency Accuracy and DAC Performance
      9. 8.3.9 PLL2 Loop Filter
    4. 8.4 Device Functional Modes
      1. 8.4.1 DUAL PLL
        1. 8.4.1.1 Dual Loop
        2. 8.4.1.2 Dual Loop With Cascaded 0-Delay
        3. 8.4.1.3 Dual Loop With Nested 0-Delay
      2. 8.4.2 Single PLL
        1. 8.4.2.1 PLL2 Single Loop
          1. 8.4.2.1.1 PLL2 Single Loop With 0-Delay
        2. 8.4.2.2 PLL2 With an External VCO
      3. 8.4.3 Distribution Mode
    5. 8.5 Programming
      1. 8.5.1 Recommended Programming Sequence
    6. 8.6 Register Maps
      1. 8.6.1 Register Map for Device Programming
      2. 8.6.2 Device Register Descriptions
        1. 8.6.2.1 System Functions
          1. 8.6.2.1.1 RESET, SPI_3WIRE_DIS
          2. 8.6.2.1.2 POWERDOWN
          3. 8.6.2.1.3 ID_DEVICE_TYPE
          4. 8.6.2.1.4 ID_PROD
          5. 8.6.2.1.5 ID_MASKREV
          6. 8.6.2.1.6 ID_VNDR
        2. 8.6.2.2 (0x100 to 0x137) Device Clock and SYSREF Clock Output Controls
          1. 8.6.2.2.1 DCLKX_Y_DIV
          2. 8.6.2.2.2 DCLKX_Y_DDLY
          3. 8.6.2.2.3 CLKoutX_Y_PD, CLKoutX_Y_ODL, CLKoutX_Y_IDL, DCLKX_Y_DDLY_PD, DCLKX_Y_DDLY[9:8], DCLKX_Y_DIV[9:8]
          4. 8.6.2.2.4 CLKoutX_SRC_MUX, DCLKX_Y_PD, DCLKX_Y_BYP, DCLKX_Y_DCC, DCLKX_Y_POL, DCLKX_Y_HS
          5. 8.6.2.2.5 CLKoutY_SRC_MUX, SCLKX_Y_PD, SCLKX_Y_DIS_MODE, SCLKX_Y_POL, SCLKX_Y_HS
          6. 8.6.2.2.6 SCLKX_Y_ADLY_EN, SCLKX_Y_ADLY
          7. 8.6.2.2.7 SCLKX_Y_DDLY
          8. 8.6.2.2.8 CLKoutY_FMT, CLKoutX_FMT
        3. 8.6.2.3 SYSREF, SYNC, and Device Config
          1. 8.6.2.3.1  VCO_MUX, OSCout_MUX, OSCout_FMT
          2. 8.6.2.3.2  SYSREF_REQ_EN, SYNC_BYPASS, SYSREF_MUX
          3. 8.6.2.3.3  SYSREF_DIV
          4. 8.6.2.3.4  SYSREF_DDLY
          5. 8.6.2.3.5  SYSREF_PULSE_CNT
          6. 8.6.2.3.6  PLL2_RCLK_MUX, PLL2_NCLK_MUX, PLL1_NCLK_MUX, FB_MUX, FB_MUX_EN
          7. 8.6.2.3.7  PLL1_PD, VCO_LDO_PD, VCO_PD, OSCin_PD, SYSREF_GBL_PD, SYSREF_PD, SYSREF_DDLY_PD, SYSREF_PLSR_PD
          8. 8.6.2.3.8  DDLYdSYSREF_EN, DDLYdX_EN
          9. 8.6.2.3.9  DDLYd_STEP_CNT
          10. 8.6.2.3.10 SYSREF_CLR, SYNC_1SHOT_EN, SYNC_POL, SYNC_EN, SYNC_PLL2_DLD, SYNC_PLL1_DLD, SYNC_MODE
          11. 8.6.2.3.11 SYNC_DISSYSREF, SYNC_DISX
          12. 8.6.2.3.12 PLL1R_SYNC_EN, PLL1R_SYNC_SRC, PLL2R_SYNC_EN, FIN0_DIV2_EN, FIN0_INPUT_TYPE
        4. 8.6.2.4 (0x146 - 0x149) CLKIN Control
          1. 8.6.2.4.1 CLKin_SEL_PIN_EN, CLKin_SEL_PIN_POL, CLKin2_EN, CLKin1_EN, CLKin0_EN, CLKin2_TYPE, CLKin1_TYPE, CLKin0_TYPE
          2. 8.6.2.4.2 CLKin_SEL_AUTO_REVERT_EN, CLKin_SEL_AUTO_EN, CLKin_SEL_MANUAL, CLKin1_DEMUX, CLKin0_DEMUX
          3. 8.6.2.4.3 CLKin_SEL0_MUX, CLKin_SEL0_TYPE
          4. 8.6.2.4.4 SDIO_RDBK_TYPE, CLKin_SEL1_MUX, CLKin_SEL1_TYPE
        5. 8.6.2.5 RESET_MUX, RESET_TYPE
        6. 8.6.2.6 (0x14B - 0x152) Holdover
          1. 8.6.2.6.1 LOS_TIMEOUT, LOS_EN, TRACK_EN, HOLDOVER_FORCE, MAN_DAC_EN, MAN_DAC[9:8]
          2. 8.6.2.6.2 MAN_DAC
          3. 8.6.2.6.3 DAC_TRIP_LOW
          4. 8.6.2.6.4 DAC_CLK_MULT, DAC_TRIP_HIGH
          5. 8.6.2.6.5 DAC_CLK_CNTR
          6. 8.6.2.6.6 CLKin_OVERRIDE, HOLDOVER_EXIT_MODE, HOLDOVER_PLL1_DET, LOS_EXTERNAL_INPUT, HOLDOVER_VTUNE_DET, CLKin_SWITCH_CP_TRI, HOLDOVER_EN
          7. 8.6.2.6.7 HOLDOVER_DLD_CNT
        7. 8.6.2.7 (0x153 - 0x15F) PLL1 Configuration
          1. 8.6.2.7.1 CLKin0_R
          2. 8.6.2.7.2 CLKin1_R
          3. 8.6.2.7.3 CLKin2_R
          4. 8.6.2.7.4 PLL1_N
          5. 8.6.2.7.5 PLL1_WND_SIZE, PLL1_CP_TRI, PLL1_CP_POL, PLL1_CP_GAIN
          6. 8.6.2.7.6 PLL1_DLD_CNT
          7. 8.6.2.7.7 HOLDOVER_EXIT_NADJ
          8. 8.6.2.7.8 PLL1_LD_MUX, PLL1_LD_TYPE
        8. 8.6.2.8 (0x160 - 0x16E) PLL2 Configuration
          1. 8.6.2.8.1 PLL2_R
          2. 8.6.2.8.2 PLL2_P, OSCin_FREQ, PLL2_REF_2X_EN
          3. 8.6.2.8.3 PLL2_N_CAL
          4. 8.6.2.8.4 PLL2_N
          5. 8.6.2.8.5 PLL2_WND_SIZE, PLL2_CP_GAIN, PLL2_CP_POL, PLL2_CP_TRI
          6. 8.6.2.8.6 PLL2_DLD_CNT
          7. 8.6.2.8.7 PLL2_LD_MUX, PLL2_LD_TYPE
        9. 8.6.2.9 (0x16F - 0x555) Misc Registers
          1. 8.6.2.9.1 PLL2_PRE_PD, PLL2_PD, FIN0_PD
          2. 8.6.2.9.2 PLL1R_RST
          3. 8.6.2.9.3 CLR_PLL1_LD_LOST, CLR_PLL2_LD_LOST
          4. 8.6.2.9.4 RB_PLL1_LD_LOST, RB_PLL1_LD, RB_PLL2_LD_LOST, RB_PLL2_LD
          5. 8.6.2.9.5 RB_DAC_VALUE (MSB), RB_CLKinX_SEL, RB_CLKinX_LOS
          6. 8.6.2.9.6 RB_DAC_VALUE
          7. 8.6.2.9.7 RB_HOLDOVER
          8. 8.6.2.9.8 SPI_LOCK
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Treatment of Unused Pins
      2. 9.1.2 Digital Lock Detect Frequency Accuracy
        1. 9.1.2.1 Minimum Lock Time Calculation Example
      3. 9.1.3 Driving CLKIN AND OSCIN Inputs
        1. 9.1.3.1 Driving CLKIN and OSCIN PINS With a Differential Source
        2. 9.1.3.2 Driving CLKIN Pins With a Single-Ended Source
      4. 9.1.4 Termination and Use of Clock Output Drivers
        1. 9.1.4.1 Termination for DC Coupled Differential Operation
        2. 9.1.4.2 Termination for AC Coupled Differential Operation
        3. 9.1.4.3 Termination for Single-Ended Operation
      5. 9.1.5 Output Termination and Biasing
        1. 9.1.5.1 LVPECL
        2. 9.1.5.2 LVDS/HSDS
        3. 9.1.5.3 CML
      6. 9.1.6 OSCin Doubler for Best Phase Noise Performance
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Device Selection
        2. 9.2.2.2 Device Configuration and Simulation
        3. 9.2.2.3 Device Setup
      3. 9.2.3 Application Curve
    3. 9.3 System Examples
      1. 9.3.1 System Level Diagram
    4. 9.4 Power Supply Recommendations
      1. 9.4.1 Current Consumption
    5. 9.5 Layout
      1. 9.5.1 Thermal Management
      2. 9.5.2 Layout Guidelines
      3. 9.5.3 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 Clock Tree Architect
        2. 10.1.1.2 PLLatinum Simulation
        3. 10.1.1.3 TICS Pro
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

9.1.4.2 Termination for AC Coupled Differential Operation

AC coupling allows for shifting the DC bias level (common mode voltage) when driving different receiver standards. Since AC coupling prevents the driver from providing a DC bias voltage at the receiver it is important to ensure the receiver is biased to its ideal DC level.

When driving non-biased LVDS receivers with an LVDS driver, the signal may be AC coupled by adding DC blocking capacitors, however the proper DC bias point needs to be established at the receiver. One way to do this is with the termination circuitry in Figure 9-9.

GUID-20230410-SS0I-M8DJ-5VVD-DBZGVZMVXBDF-low.svg Figure 9-9 Differential LVDS Operation, AC Coupling, External Biasing at the Receiver

Some LVDS receivers may have internal biasing on the inputs. In this case, the circuit shown in Figure 9-9 is modified by replacing the 50 Ω terminations to Vbias with a single 100 Ω resistor across the input pins of the receiver, as shown in Figure 9-10. When using AC coupling with LVDS outputs, there may be a startup delay observed in the clock output due to capacitor charging. The previous figures employ a 0.1 µF capacitor. This value may need to be adjusted to meet the startup requirements for a particular application.

GUID-20230410-SS0I-PQ3T-3GBJ-GGRB1XBTLKHP-low.svg Figure 9-10 LVDS Termination for a Self-Biased Receiver

LVPECL drivers require a DC path to ground. When AC coupling an LVPECL signal use 120 Ω emitter resistors close to the LVPECL driver to provide a DC path to ground as shown in Figure 9-11. For proper receiver operation, the signal should be biased to the DC bias level (common mode voltage) specified by the receiver. The typical DC bias voltage for LVPECL receivers is 2 V. A Thevenin equivalent circuit (82 Ω resistor connected to VCC and a 120 Ω resistor connected to ground with the driver connected to the junction of the 82 Ω and 120 Ω resistors) is a valid termination as shown in Figure 9-11 for VCC = 3.3 V. Note this Thevenin circuit is different from the DC coupled example in Figure 9-8.

GUID-20230410-SS0I-VDLR-TZ5B-XMCH0DXTNXJK-low.svg Figure 9-11 Differential LVPECL Operation, AC Coupling, Thevenin Equivalent, External Biasing at the Receiver