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LMH1983: CLKout of LMH1983 can be broken up ? when other CLKouts are changed.

Part Number: LMH1983

Hi Team,

My name is Maki and work for Osaka office in Japan as a FAA.

I have an inquiry regarding CLKouts of LMH1983.

According to DS of LMH1983, the CLK generator has four PLLs for Simultaneous A/V Clock Generation.

and my customer is now planning:

   Input: 27MHz, H/V/FID
   Output 1: 148.35MHz or 148.5MHz (for Camera head transmission)
   Output 2: 148.35MHz or 148.5MHz or 54MHz (refclk for 1 HDMI channel)
   Output 3: 148.35MHz or 148.5MHz or 74.25MHz or 74.175MHz or 54MHz (refclk for 2 HDMI lines)

Is it possible?

and my customer wants to make sure that Output 1 is not interrupted when Output 2 or Output 3 are changed.

Best Regards,

Maki

  • Hi Maki, 

    The LMH1983 can produce the following frequencies:

    -          PLL1: 27 MHz (or 13.5 MHz if divide by 2 is enabled)

    -          PLL2: 148.5 MHz (or 74.25 MHz if divide by 2 is enabled)

    -          PLL3: 148.35 MHz (or 74.18 MHz if divide by 2 is enabled)

    -          PLL4: 24.576 MHz by default but most variability

    • 98.304 MHz divided by 4 in default (2^2)
    • Divider is in powers of 2 and can be set as high as 15 (98.304 MHz divided by 2^15 – 94.304 MHz / 32,768)

     

    Output 1 can only bring out PLL1, Output 2/3 can choose between PLL1/2/3, and output 4 only brings out PLL4.

    The only frequency which cannot be supported is the 54 MHz listed below.

    An yes, output 1 should keep running irrelevant of updates to output 2 and output 3.

    Thanks and regards,

    Amin

  • Hi Amin,

    Thank you for your continued support.

    Best regards,

    Maki