SNAS850 December   2024 LMX1205

ADVANCE INFORMATION  

  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 Input
        1. 6.3.3.1 Clock Input Adjustable Delay
      4. 6.3.4 Clock Outputs
        1. 6.3.4.1 Clock Output Buffers
        2. 6.3.4.2 Clock Output Adjustable Delay
        3. 6.3.4.3 Clock MUX
        4. 6.3.4.4 Clock Divider
        5. 6.3.4.5 Clock Multiplier
          1. 6.3.4.5.1 General Information About the Clock Multiplier
          2. 6.3.4.5.2 State Machine Clock for the Clock Multiplier
            1. 6.3.4.5.2.1 State Machine Clock
          3. 6.3.4.5.3 Calibration for the Clock Multiplier
          4. 6.3.4.5.4 Lock Detect for the Clock Multiplier
      5. 6.3.5 LOGICLK Outputs
        1. 6.3.5.1 LOGICLK Output Format
        2. 6.3.5.2 LOGICLK 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 LOGISYSREF Output Buffer
          3. 6.3.6.1.3 SYSREF Frequency and Delay Generation
          4. 6.3.6.1.4 SYSREFREQ Pins and SYSREFREQ SPI Controlled Fields
            1. 6.3.6.1.4.1 SYSREFREQ Pins Common-Mode Voltage
            2. 6.3.6.1.4.2 SYSREFREQ Windowing Feature
              1. 6.3.6.1.4.2.1 General Procedure Flowchart for SYSREF Windowing Operation
              2. 6.3.6.1.4.2.2 Other Guidance For SYSREF Windowing
              3. 6.3.6.1.4.2.3 For Glitch-Free Output
              4. 6.3.6.1.4.2.4 If Using SYNC Feature
              5. 6.3.6.1.4.2.5 SYNC Feature
      7. 6.3.7 Power-Up Timing
      8. 6.3.8 Treatment of Unused Pins
    4. 6.4 Device Functional Modes Configurations
  8. 7 Register Map
    1. 7.1 Device Registers
  9. 8 Application and Implementation
    1. 8.1 Reference
      1. 8.1.1 Typical Application
        1. 8.1.1.1 Design Requirements
        2. 8.1.1.2 Detailed Design Procedure
        3. 8.1.1.3 Application Plots
    2. 8.2 Power Supply Recommendations
    3. 8.3 Layout
      1. 8.3.1 Layout Guidelines
      2. 8.3.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.1 Power On Reset

When the device is powered up, the power on reset (POR) resets all registers to a default state as well as resets all state machines and dividers. For the power on reset state, all SYSREF outputs are disabled and all the dividers are bypassed; the device functions as a 4-output buffer. Users must wait 100µs after the power supply rails before programming other registers to verify that the RESET is finished. If the power on reset happens when there is no device clock present, the device functions properly, however, the current changes once an input clock is presented.

\Performing a software power on reset by writing RESET=1 in the SPI bus is both possible and generally good practice. The RESET bit self-clears once any other register is written to. The SPI bus can be used to override these states to the desired settings.

Although the device does have an automatic power on reset, the device can be impacted by different ramp rates on the different supply pins, especially in the presence of a strong input clock signal. Performing a software reset after POR is recommended. This reset can be done by programming RESET=1. The reset bit can be cleared by programming any other register or setting RESET back to zero. Even at maximum allowed SPI bus speed, the software reset event always completes before the subsequent SPI write.