SNLS534D April   2016  – June 2018 LMH1226

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Block Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Recommended SMBus Interface AC Timing Specifications
    7. 6.7 Serial Parallel Interface (SPI) AC Timing Specifications
    8. 6.8 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 4-Level Input Configuration Pins
      2. 7.3.2 Input Carrier Detect
      3. 7.3.3 Continuous Time Linear Equalizer (CTLE)
        1. 7.3.3.1 Adaptive PCB Trace Equalizer (IN1±)
      4. 7.3.4 Input-Output Mux Selection
      5. 7.3.5 Clock and Data Recovery (CDR) Reclocker
      6. 7.3.6 Internal Eye Opening Monitor (EOM)
      7. 7.3.7 Output Function Control
      8. 7.3.8 Output Driver Amplitude and De-Emphasis Control
      9. 7.3.9 Status Indicators and Interrupts
        1. 7.3.9.1 LOCK_N (Lock Indicator)
        2. 7.3.9.2 CD_N (Carrier Detect)
        3. 7.3.9.3 INT_N (Interrupt)
    4. 7.4 Device Functional Modes
      1. 7.4.1 System Management Bus (SMBus) Mode
        1. 7.4.1.1 SMBus Read and Write Transactions
          1. 7.4.1.1.1 SMBus Write Operation Format
          2. 7.4.1.1.2 SMBus Read Operation Format
      2. 7.4.2 Serial Peripheral Interface (SPI) Mode
        1. 7.4.2.1 SPI Read and Write Transactions
          1. 7.4.2.1.1 SPI Write Transaction Format
          2. 7.4.2.1.2 SPI Read Transaction Format
        2. 7.4.2.2 SPI Daisy Chain
    5. 7.5 LMH1226 Register Map
      1. 7.5.1 Share Register Page
      2. 7.5.2 CTLE/CDR Register Page
      3. 7.5.3 Drivers Register Page
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 General Guidance for SMPTE and 10 GbE Applications
      2. 8.1.2 LMH1219 and LMH1226 Compatibility
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Recommended VOD and DEM Register Settings
      4. 8.2.4 Application Performance Plots
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 PCB Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    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

7.3.8 Output Driver Amplitude and De-Emphasis Control

The VOD_DE control pin selects the output amplitude and de-emphasis settings for both OUT0 and OUT1. It offers users the capability to select higher output amplitude and de-emphasis levels for longer board trace that connects the drivers to their downstream receivers. Driver de-emphasis provides transmitter equalization to reduce the ISI caused by the board trace.

By default, the output driver VOD and de-emphasis settings are configured by the VOD_DE pin logic settings shown in Table 5. These settings can be overridden via register control by applying the appropriate override bit values. When these parameters are controlled by registers, the VOD and de-emphasis levels for each channel can be programmed independently. For more information, refer to the LMH1226 Register Map.

Table 5. Recommended VOD_DE Pin and Register Settings for Different FR4 Trace Lengths(1)

VOD_DE
LEVEL		 VOD REG SETTING
OUT0±: 0x30[5]=1, 0x30[2:0]
OUT1±: 0x32[5]=1, 0x32[2:0] 		DEM REG SETTING
OUT0±: 0x31[6]=1, 0x31[2:0]
OUT1±: 0x33[6]=1, 0x33[2:0] 		VOD (mVpp)(2) VODDE (mVpp)(2) DEM (dB) FR4 TRACE LENGTH (inches)
H 0 0 410 410 0 0 – 1
F 2 2 560 500 -0.9 2 – 4
R 3 3 635 480 -2.4 5 – 6
L 5 5 810 480 -6.1 7 – 8
(1) The output drivers are capable of providing higher VOD and DEM levels (max settings are 7). For more VOD and de-emphasis levels, refer to Table 10.
(2) See Figure 13.
LMH1226 snls475_vod_de_level.gifFigure 13. VOD and VODDE Levels