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CDCLVP1216: What is the time from toggling the “IN_SEL”-pin until the “IN_MUX” is toggled?

Part Number: CDCLVP1216
Other Parts Discussed in Thread: CDCLVP1204

Hello, 

Have a customer that can’t find any info in the datasheet of the speed of the IN_SEL pin of the CDCLVP1216:


In our application we want to be able to send the clocks in bursts and it is important that we have control over when the first pulse comes.

  • What is the time from toggling the “IN_SEL”-pin until the “IN_MUX” is toggled?

  

Best regards

Jorgen

  • Hi Jorgen,

    Please see this e2e post on the CDCLVP1204 IN_SEL timing. The CDCLVP1216 can be estimated to have a similar delay (1us).

    Regards,

    Jennifer

  • Hi Jennifer, 

    Thanks for the reference. It seems that this is not a parameter that we can guarantee, is that correct?

    Thanks & regards

    Jorgen

  • Hi Jorgen,

    That is correct.

    Regards,

    Jennifer

  • Hi Jennifer, 

    The customer have a slight different use case.

    As he understands from the link, they toggle between two 156,25MHz clocks and they seem to be 180 degrees phase shifted. So, shifting from input 0 to input 1 seems to make a small glitch, but when the next pulse arrives it, about 8ns later, it seems that its’ working ok

    His question is how long it would take to toggle between the 2 inputs. In the picture above, it looks like about 8ns not the 1us. But would it be possible to toggle even quicker if the glitch only depends if you have toggled the input in the middle of the raising clock?

    In their application they are planning to use the IN_SEL mux more like an enable/disable function by toggling between one input with a signal and one input without any signal.

    He also would like to confirm that it is only when you toggle between IN1 to IN0 that the part has a long “settling time”. If they make sure they have the valid signal on IN1 and ground IN0, would the part behave like as they want?

    Best regards

    Jorgen

  • Hi Jorgen,

    We gave a 1us settling time to account for the worst case when switching from IN1 to IN0. It's possible that the "glitch" can last much less and that putting ground on IN0 would reduce the settling time (in comparison to a pulsing signal on IN0). However, we can't guarantee the part will behave without the settling time when IN0 = GND.

    IN0 to IN1 shouldn't experience the "glitch".

    Regards,

    Jennifer