SNLS309I April   2010  – December 2014 LMH1983

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configurations 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 Frame Timing Outputs Timing Requirements
    7. 7.7 Frame Timing Outputs Switching Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Control of PLL1
      2. 8.3.2  PLL1 Loop Response Design Equations
      3. 8.3.3  Control of PLL2 and PLL3
      4. 8.3.4  Control of PLL4
      5. 8.3.5  Clock Output Jitter
      6. 8.3.6  Lock Determination
      7. 8.3.7  Lock Time Considerations
      8. 8.3.8  LOR Determination
      9. 8.3.9  Output Driver Adjustments
      10. 8.3.10 TOF1 Alignment
      11. 8.3.11 TOF2 and TOF3 Alignment
        1. 8.3.11.1 TOF3 Initialization Set Up
      12. 8.3.12 TOF4 Alignment
    4. 8.4 Device Functional Modes
      1. 8.4.1 Reference Detection
      2. 8.4.2 User Defined Formats
      3. 8.4.3 Auto Format Detection Codes
      4. 8.4.4 Free-Run, Genlock, and Holdover Modes
    5. 8.5 Programming
      1. 8.5.1 I2C Interface Protocol
      2. 8.5.2 Write Sequence
      3. 8.5.3 Read Sequence
    6. 8.6 Register Map
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Genlock Timing Generation with NTSC 525i/29.97 High Speed Reference
        1. 9.2.1.1 Design Requirements
          1. 9.2.1.1.1 VCXO Selection Criteria
          2. 9.2.1.1.2 Loop Filter Capacitors
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 A/V Clock Generation with Recognized Clock-based Input Reference
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curve
      3. 9.2.3 A/V Clock Generation Using Free-Run Mode
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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1 Features

  • Four PLLs for Simultaneous A/V Clock Generation
    • PLL1: 27 or 13.5 MHz
    • PLL2: 148.5 or 74.25 MHz
    • PLL3: 148.5/1.001 or 74.25/1.001 MHz
    • PLL4: 98.304 MHz / 2X (X = 0 to 15)
  • 3 x 2 Video Clock Crosspoint
  • Flexible PLL Bandwidth to Optimize Jitter Performance and Lock Time
  • Soft Resynchronization to New Reference
  • Digital Holdover or Free-run on Loss of Reference
  • Status Flags for Loss of Reference and Loss of PLL Lock
  • 3.3 V Single Supply Operation
  • I2C Interface with Address Select Pin (3 States)

2 Applications

  • Triple Rate (3G/HD/SD) SDI SerDes
  • FPGA Reference Clock Generation/Cleaning
  • Audio Embed or De-embed
  • Video Cameras
  • Frame Synchronizers (Genlock, DARS)
  • A-D or D-A Conversion, Editing, Processing Cards
  • Keyers and Logo Inserters
  • Format or Standards Converters
  • Video Displays and Projectors
  • A/V Test and Measurement Equipment

3 Description

The LMH1983 is a highly-integrated programmable audio/video (A/V) clock generator intended for broadcast and professional applications. It can replace multiple PLLs and VCXOs used in applications supporting SMPTE serial digital video (SDI) and digital audio AES3/EBU standards. It offers low-jitter reference clocks for any SDI transmitter to meet stringent output jitter specifications without additional clock cleaning circuits.

The LMH1983 features automatic input format detection, simple programming of multiple A/V output formats, genlock or digital free-run modes, and override programmability of various automatic functions. The recognized input formats include HVF syncs for the major video standards, 27 MHz, 10 MHz, and 32/44.1/48/96 kHz audio word clocks.

The dual-stage PLL architecture integrates four PLLs with three on-chip VCOs. The first stage (PLL1) uses an external low-noise 27 MHz VCXO with narrow loop bandwidth to provide a clean reference clock for the next stage. The second stage (PLL2, 3, 4) consists of three parallel VCO PLLs for simultaneous generation of the major digital A/V clock fundamental rates, including 148.5 MHz, 148.5/1.001 MHz, and 98.304 MHz (4 × 24.576 MHz). Each PLL can generate a clock and a timing pulse to indicate top of frame (TOF).

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LMH1983 WQFN (40) 6.00 mm × 6.00 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Typical Application Block Diagram

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