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Calculation of latency between DS90UH925Q-Q1 and DS90UH926Q-Q1.

Nao
Genius 4905 points
Other Parts Discussed in Thread: DS90UH925Q-Q1, DS90UH926Q-Q1

Hello E2E members,

How do we calculation of latency between DS90UH925Q-Q1 and DS90UH926Q-Q1?

Assume a 720P video signal at 85MHz with 24-Bit color depth.

I saw a field that states 145T(DS90UH925Q-Q1) and 147T(DS90UH926Q-Q1) in each datasheet.
If I am running the equation correctly, this comes to the following...

145 * ( 1 / 85,000,000 ) + 147 * ( 1 / 85,000,000 )
= 145 * 11.76ns + 147 * 11.76ns = 3433.92ns

Is my interpretation of this datasheet correct?

Regards,

Nao

  • 0
    TI__Genius 13475 points
    Nao
    The latency is measured from the PCLK going into the serializer to the corresponding PCLK coming out of the deserializer, and as such includes all of the system delays of both the serializer, the deserializer and the interconnect. There is no need to add the two latency numbers from the serializer and the deserializer, the total latency will be approximately half of what you calculated.
  • 0 in reply to Mark Sauerwald88474
    Genius 4905 points

    Hi, Mark-san,

    Thank you for your quick reply, but I couldn't understand your answer what the total latency is half of adding the serializer and the deserializer.

    So, could you explain more detail about this?

    I appreciate your support for this.

    Regards,

    Nao

  • 0 in reply to Nao
    TI__Genius 13475 points

    We define the latency from the time of the PCLK going into the serializer to the corresponding PCLK coming from the deserializer, so the latency number specified includes both the serializer and the deserializer.   Therefore either the number for the serializer OR the number for the deserializer can be used, but by adding both, you are double counting the time for the transmission.