SNLS289D April   2008  – September 2015 LMH1982

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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Supported Standards and Timing Formats
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
        1. 7.4.1.1 Free Run Mode
        2. 7.4.1.2 Genlock Mode
          1. 7.4.1.2.1 Genlock Mode State Diagram
            1. 7.4.1.2.1.1 Loss of Reference (LOR)
              1. 7.4.1.2.1.1.1 Free Run during LOR
              2. 7.4.1.2.1.1.2 Holdover during LOR
    5. 7.5 Programming
      1. 7.5.1 I2C Interface Protocol
        1. 7.5.1.1 Write Sequence
        2. 7.5.1.2 Read Sequence
        3. 7.5.1.3 I2C Enable Control Pin
    6. 7.6 Register Maps
      1. 7.6.1 I2C Interface Control Register Definitions
        1. 7.6.1.1 Genlock and Input Reference Control Registers
        2. 7.6.1.2 Genlock Status And Lock Control Register
        3. 7.6.1.3 Input Control Register
        4. 7.6.1.4 PLL 1 Divider Register
        5. 7.6.1.5 PLL 4 Charge Pump Current Control Register
        6. 7.6.1.6 Output Clock and TOF Control Register
        7. 7.6.1.7 TOF Configuration Registers
        8. 7.6.1.8 PLL 1, 2, 3 Charge Pump Current Control Registers
        9. 7.6.1.9 Reserved Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 148.35 MHz PLL Initialization Sequence
      2. 8.1.2 Enabling Genlock Mode
      3. 8.1.3 Output Disturbance While Output Alignment Mode Enabled
      4. 8.1.4 Evaluating the LMH1982
      5. 8.1.5 Input Reference
        1. 8.1.5.1 Reference Frame Decoder
      6. 8.1.6 Output Clocks and TOF
        1. 8.1.6.1 Programming the Output Clock Frequencies
        2. 8.1.6.2 Programming the Output Format Timing
          1. 8.1.6.2.1 Output TOF Clock
          2. 8.1.6.2.2 Output Frame Timing
            1. 8.1.6.2.2.1 HD Format TOF Generation Using a 27-MHz TOF Clock
          3. 8.1.6.2.3 Reference Frame Timing
          4. 8.1.6.2.4 Input-Output Frame Rate Ratio
          5. 8.1.6.2.5 Output Frame Line Offset
        3. 8.1.6.3 Programming the Output Initialization Sequence
          1. 8.1.6.3.1 TOF Output Delay Considerations
          2. 8.1.6.3.2 Output Clock Initialization Without TOF
        4. 8.1.6.4 Output Behavior Upon Loss Of Reference
      7. 8.1.7 Reference And Pll Lock Status
        1. 8.1.7.1 Reference Detection
          1. 8.1.7.1.1 Programming the Loss of Reference (LOR) Threshold
        2. 8.1.7.2 PLL Lock Detection
          1. 8.1.7.2.1 Programming the PLL Lock Threshold
          2. 8.1.7.2.2 PLL Lock Status Instability
      8. 8.1.8 Loop Response
        1. 8.1.8.1 Loop Response Design Equations
          1. 8.1.8.1.1 Loop Response Optimization Tips
          2. 8.1.8.1.2 Loop Filter Capacitors
        2. 8.1.8.2 Lock Time Considerations
        3. 8.1.8.3 VCXO Considerations
        4. 8.1.8.4 Free Run Output Jitter
    2. 8.2 Typical Applications
      1. 8.2.1 Analog Reference Genlock for Triple-Rate SDI Video
        1. 8.2.1.1 Design Requirements
          1. 8.2.1.1.1 Programming the PLL 1 Dividers
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Procedure for Designing the PLL 1 Dividers
      2. 8.2.2 SDI Reference Genlock for Triple-Rate SDI Video
      3. 8.2.3 Triple-Rate SDI Loop-through
      4. 8.2.4 Combined Genlock or Loop-Through for Triple-Rate SDI Video
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Sequencing
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9 Power Supply Recommendations

9.1 Power Supply Sequencing

The VDD (3.3 V) and DVDD (2.5 V) power supply pins are isolated by internal ESD structures that may become forward biased when DVDD is higher than VDD. Exposure to this condition, when prolonged and excessive, can trigger latch-up and/or reduce the reliability of the device. Therefore, the LMH1982 has a recommended power supply sequence.

On device power-up, the VDD supply must be brought up before the DVDD supply. On power-down, the DVDD supply must be brought down before the VDD supply. The starting points and ramp rates of the supplies should be considered to determine the relative timing of the power-up and power-down sequences such that DVDD does not exceed VDD +0.3 V as shown in the Absolute Maximum Ratings.

To minimize the potential for latch-up, a Schottky diode can be externally connected between the DVDD supply (anode) and VDD supply (cathode). If DVDD is brought up first, the Schottky will ensure that VDD is within about 0.3 V of DVDD until VDD is brought up.

Additionally, the device input pins (except for SDA and SCL inputs) should not be driven prior to power-up due to the same reasons provided above for the power pins. Otherwise, a small series resistor should be used on each input pin to protect the device by limiting the current whenever the internal ESD structures become forward biased.

Once both supplies are powered up in the proper sequence, the device has a power on reset sequence that will reset all registers to their default values.