SNAS883 June   2024 LMX1860-SEP

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 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 Requirements
    7. 5.7 Timing Diagram
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
      1. 6.1.1 Range of Dividers and Multiplier
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Power On Reset
      2. 6.3.2 Temperature Sensor
      3. 6.3.3 Clock Outputs
        1. 6.3.3.1 Clock Output Buffers
        2. 6.3.3.2 Clock MUX
        3. 6.3.3.3 Clock Divider
        4. 6.3.3.4 Clock Multiplier
          1. 6.3.3.4.1 General Information about the Clock Multiplier
          2. 6.3.3.4.2 State Machine Clock for the Clock Multiplier
            1. 6.3.3.4.2.1 State Machine Clock
          3. 6.3.3.4.3 Calibration for the Clock Multiplier
          4. 6.3.3.4.4 Lock Detect for the Clock Multiplier
          5. 6.3.3.4.5 Watchdog Timer
      4. 6.3.4 Device Functional Modes Configurations
      5. 6.3.5 LOGICLK Output
        1. 6.3.5.1 LOGICLK Output Format
        2. 6.3.5.2 LOGICLK_DIV_PRE and LOGICLK_DIV Dividers
      6. 6.3.6 SYSREF
        1. 6.3.6.1 SYSREF Output Buffers
          1. 6.3.6.1.1 SYSREF Output Buffers for Main Clocks (SYSREFOUT)
          2. 6.3.6.1.2 SYSREF Output Buffer for LOGICLK
        2. 6.3.6.2 SYSREF Frequency and Delay Generation
        3. 6.3.6.3 SYSREFREQ Pins and SYSREFREQ_FORCE Field
          1. 6.3.6.3.1 SYSREFREQ Pins Common-Mode Voltage
          2. 6.3.6.3.2 SYSREFREQ Windowing Feature
            1. 6.3.6.3.2.1 General Procedure Flowchart for SYSREF Windowing Operation
            2. 6.3.6.3.2.2 SYSREFREQ Repeater Mode With Delay Generation (Retime)
            3. 6.3.6.3.2.3 Other Guidance For SYSREF Windowing
            4. 6.3.6.3.2.4 For Glitch-Free Output
            5. 6.3.6.3.2.5 If Using SYNC Feature
          3. 6.3.6.3.3 SYNC Feature
      7. 6.3.7 Pin Mode Control
        1. 6.3.7.1 Chip Enable (CE)
        2. 6.3.7.2 Output Channel Control
        3. 6.3.7.3 Logic Output Control
        4. 6.3.7.4 SYSREF Output Control
        5. 6.3.7.5 Device Mode Selection
        6. 6.3.7.6 Divider or Multiplier Value Selection
        7. 6.3.7.7 Calibration Control Pin
        8. 6.3.7.8 Output Power Control
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 SYSREFREQ Input Configuration
      2. 7.1.2 Treatment of Unused Pins
      3. 7.1.3 Current Consumption
    2. 7.2 Typical Applications
      1. 7.2.1 Local Oscillator Distribution Application
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Plot
      2. 7.2.2 JESD204B/C Clock Distribution Application
    3. 7.3 Layout
      1. 7.3.1 Layout Guidelines
      2. 7.3.2 Layout Example
    4. 7.4 Power Supply Recommendations
      1. 7.4.1 Power-Up Timing
    5. 7.5 Register Map
      1. 7.5.1 Device Registers
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.1.1 SYSREFREQ Input Configuration

The SYSREFREQ pins support single-ended or differential input in AC or DC coupling mode. The SYSREFREQ pins have an internal 50Ω termination with capacitive ground, which acts as 100Ω differential.

Figure 7-1 shows the generic SYSREFREQ input circuit recommendation to support all AC/DC, single-ended or differential inputs. Some of the discrete components in Figure 7-1 are just placeholder for individual input signal (single-ended or differential input) and AC or DC coupled input.

LMX1860-SEP SYSREFREQ Input Circuit Recommendations Figure 7-1 SYSREFREQ Input Circuit Recommendations

The following figures show the individual circuit diagram for each configurations:

LMX1860-SEP AC-Coupled Differential InputFigure 7-2 AC-Coupled Differential Input
LMX1860-SEP DC-Coupled Differential InputFigure 7-4 DC-Coupled Differential Input
LMX1860-SEP AC-Coupled, Single-Ended InputFigure 7-3 AC-Coupled, Single-Ended Input
LMX1860-SEP DC-Coupled, Single-Ended InputFigure 7-5 DC-Coupled, Single-Ended Input
  1. AC coupled differential and single-ended input configurations required the resistor terminations (R2 and R3) to create the VCM at each pin and resistor values must select to maintain greater than 150mV potential difference between pin P and pin N.
    1. As an example, to create the VCM of 1.5V at pin P and 1.65V at pin N, with the 2.5V VCC, set R3 = 550Ω and R2 = 1kΩ
    2. For single-ended input configuration, place R6 = 50Ω to avoid any reflection at complementary input pin.
  2. DC coupled differential and single-ended input configuration required to have the source common-mode voltage matched with the device input common mode specifications.
    1. For single-ended input configuration, keep the R1, R2, R3 and R4 resistors. This method creates the same common-mode voltage at both pins, and the resistive dividers create 75Ω at pin P and 50Ω Thevenin's equivalent at pin N.
    2. As an example, to have the common-mode voltage of 1.35V at each pin, set the resistive divider components values to R1 = 130Ω, R2 = 165Ω, R3 = 86.6Ω and R4 = 110Ω with the 2.5V VCC.