LMH1983: TOF2/3/4 Alignment not detected, while PLL Locked

Part Number: LMH1983


It was found in LMH1983 prototype, that TOF2/3/4 can not detected, but PLL1/2/3/4 are all locked.

Would you help analysis this issue? As TOF2/3/4 are used for external LED indicators. In circuit, D18 LED is off, D17 and D19 are on.


Best Regards

Rocky Chen

4 Replies

  • Adding some pictures in case they were missing in questions

  • In reply to Rocky Chen:


    Are they providing H, V, F sync inputs? 

    Did they follow the TOF alignment programming steps in datasheet sections 8.3.10-8.3.12?


  • In reply to Alan O:

    Hi Alan

    Yes, there is H,V,F sync input provided, and customer followed the section of 8.3.10-8.3.12. But the issue is still there.....Any other clue or ways we can try?

  • In reply to Rocky Chen:

    Please provide the following info:

    1. Which input timing format?  Provide H/V/F sync input waveforms.
    2. Do they require only one, two, three, or all/four PLL clock and TOF domains simultaneously?  If so, which output timing format for each TOF domain?  
    3. Provide register programming sequence for device initialization and then for TOF alignment.  If possible, specify register name/address and reg data in hex.
    4. Provide full LMH1983 schematic.