SNAU305 February   2025 LMH1229 , LMH1239

 

  1.   1
  2.   LMH1229 and LMH1239 Programming Guide
  3.   Trademarks
  4. 1Access Methods
    1. 1.1 Register Programming Through SMBus
    2. 1.2 Register Programming Through SPI
    3. 1.3 Register Pages
  5. 2Register Command Syntax
  6. 3Device Configurations
    1. 3.1  Common Device Configuration
    2. 3.2  Common Register Commands
      1. 3.2.1 Channel Control
      2. 3.2.2 LMH12x9 Resets
        1. 3.2.2.1 LMH12x9 ENABLE Pin Override
        2. 3.2.2.2 LMH12x9 Share, CDR, and EQ/Drivers Page Resets
    3. 3.3  IN_MUX_SEL Override
    4. 3.4  Signal Detect Status for SDI_IN± and SDI_IN1±
      1. 3.4.1 Force Signal Detect Power Down
    5. 3.5  Lock Data Rate Indication
    6. 3.6  CDR Loop Bandwidth Override
    7. 3.7  Selective SMPTE Data Rate Lock
      1. 3.7.1 Digital Mute Reference Threshold
      2. 3.7.2 CTLE Index Check and Manual CTLE Override
    8. 3.8  Eye Opening Monitoring Operation
      1. 3.8.1 Fast EOM
        1. 3.8.1.1 Fast EOM Operation
      2. 3.8.2 Read Horizontal and Vertical Eye Opening
    9. 3.9  SDI_OUT±, OUT0± and OUT1± Default Mode of Operation
      1. 3.9.1 SDI_OUT±, OUT0± and OUT1± Independent Control
    10. 3.10 Invert OUT0±, OUT1±, and SDI_OUT± Data Polarity
    11. 3.11 OUT0±, OUT1±, and SDI_OUT± Driver Settings
      1. 3.11.1 OUT0± and OUT1± VOD Settings
      2. 3.11.2 OUT0± and OUT1± De-Emphasis Settings
      3. 3.11.3 SDI_OUT± VOD Settings
      4. 3.11.4 SDI_OUT± Pre-Emphasis
      5. 3.11.5 Output Driver Power Down
      6. 3.11.6 Cable Fault Detection (CFD)
    12. 3.12 LOCK_N Pin Output Settings
      1. 3.12.1 Interrupt Outputs Programmed by Interrupt Registers
    13. 3.13 PRBS Generator and Checker
    14. 3.14 CDR Lock Timing Control
      1. 3.14.1 Watchdog Timer
  7. 4Register Maps
    1. 4.1 Share Registers
    2. 4.2 CDR Registers
    3. 4.3 EQ_Drivers Registers

3.7 Selective SMPTE Data Rate Lock

By default, the LMH12x9 searches to lock to different data rates starting with 12G, followed by 6G, 3G, HD and ending with SD. To reduce the CDR lock adaptation search time the user can program the LMH12x9 to search within a subset of rates. For example, the user can adjust the starting and ending rates to 6G and HD, respectively, to make the LMH12x9 search to lock starting with 6G, then to 3G, and end with HD.

Note:

The start and end rate can be set to the same value.

Table 3-15 Enable Selective SMPTE CDR Data Rate Lock
REGISTERFUNCTION

Reg 0x7E[7]

Reserved

Reg 0x7E[6:4]

//Reg 0x7E[6:4] = 3'b000 sets the CDR lock search end rate to 11.88Gbps

//Reg 0x7E[6:4] = 3'b001 sets the CDR lock search end rate to 5.94Gbps
//Reg 0x7E[6:4] = 3'b010 sets the CDR lock search end rate to 2.97Gbps
//Reg 0x7E[6:4] = 3'b011 sets the CDR lock search end rate to 1.485Gbps
//Reg 0x7E[6:4] = 3'b100 sets the CDR lock search end rate to 270Mbps
Reg 0x7E[3]Reserved
Reg

0x7E[2:0]

//Reg 0x7E[2:0] = 3'b000 sets the CDR lock search start rate to 11.88Gbps
//Reg 0x7E[2:0] = 3'b001 sets the CDR lock search start rate to 5.94Gbps
//Reg 0x7E[2:0] = 3'b010 sets the CDR lock search start rate to 2.97Gbps
//Reg 0x7E[2:0] = 3'b011 sets the CDR lock search start rate to 1.485Gbps
//Reg 0x7E[2:0] = 3'b100 sets the CDR lock search start rate to 270Mbps

For example, the user can set the starting rate for the search to 12G and the ending rate to 270M (default setting).

Table 3-16 Search All Data Rates
COMMANDREGISTERVALUEMASK//COMMENTS
RAWFF0507//Select EQ/Drivers Register Page
RAW

7E

00

07

//Coarse EQ search start rate is 12G

RAW7E

40

70

//Coarse EQ search end rate is 270M

//Toggle the ENABLE pin

Alternatively, the user can restrict the data rate search.

Table 3-17 Restrict the Data Rate Search
COMMANDREGISTERVALUEMASK//COMMENTS
RAWFF0507//Select EQ/Drivers Register Page
RAW

7E

02

07

//Coarse EQ search start rate is 3G

RAW7E

40

70

//Coarse EQ search end rate is 270M

//Toggle the ENABLE pin