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LMH1983 TOF Output

chunghsienlee
Prodigy 60 points

Other Parts Discussed in Thread: LMH1983

Hi all,

 While using LMH1983 for genlock application I have a question needs help about the TOF signal.

Because of HW limitation, I use the Crosspoint output for PLL, switching between 74.25 and 74.17..

I thought the TOF output will change accordingly like described at page 15.

After measurement, the output will be controlled by 0x07 and no 59.94Hz support only 50/ 60.

 My question is how could I switch the TOF3 output to TOF2 like did in clock output ?

Best Regards,

Johnson

  • 0
    TI__Genius 13475 points

    Johnson

    The crosspoint only has the Clocks going through it - the TOF signals are independent.   To switch TOF as well as clock, you would need to use an external crosspoint switch.

    Mark

     

  • 0 in reply to Mark Sauerwald88474
    Prodigy 240 points

    Wait a second.  In the datasheet the pin description for Fout3 says:

    Video frame timing signal for OUT3 (active low). Timing generator assignable to PLL1, PLL2, or PLL3. OUT3 format is selectable via the host.

    So, how to assign it PLL2 as timing generator?

  • 0 in reply to Alex Arango
    TI__Genius 13475 points

    Each of the FOUT signals is derived from it's associated PLL:  FOUT1 is derived from PLL1, FOUT2 from PLL2 etc.  For each FOUT signal, there is a video format associated with it, which must be compatible with the data rate of the appropriate PLL - for example, you could associate the 1080P59.94 format to FOUT3, since PLL3 runs at the appropriate data rate for 1080P59.94, but you would not be able to associate the 1080P50 format to PLL3 -that would have to be associated with FOUT2.

    FOUT3 cannot use PLL2 as it's clock source....