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SN74AHC1G125 : Frequency characteristic

Junya Kato
Expert 1635 points
Other Parts Discussed in Thread: SN74AHC1G125

Hello Team,


If we use SN74AHC1G125 as a clock buffer,
Please tell us SN74AHC1G125 can use to what extent the frequency.


Best regards,
Kato

  • 0
    Guru 74080 points

    There is no value given in the datasheet. You can have a look at the propagation delays for your operating temperature. But of course this also depends on the fan out, means how many devices are connected to the buffer.

  • 0
    TI__Guru 55970 points

    Hi Junya ,

    The product folder indicates the frequency support for AHC devices to be around 75Mhz.

    What is the desired frequency needed and what is the application use case? for faster freq support and faster prop delay times consider the AUC family which supports 250Mhz .

  • 0 in reply to ShreyasRao
    Guru 74080 points

    ShreyasRao said:
    The product folder indicates the frequency support for AHC devices to be around 75Mhz.

    I think this should be listed in the datasheet as well. The product overview lists it, right.

    But the nominal value of 75MHz matches the typical propagation delays given in the datasheet:

    For a load capacitance of 15pF, one cycle is:

    2 * 5.6ns = 11.2ns

    f = 1 / 11.2ns = ~89MHz

    For a load capacitance of 50pF, one cycle is:

    2 * 8.1ns = 16.2ns

    f = 1 / 16.2ns = ~62MHz

    The difference between both is 27MHz and this halved is 13.5MHz. If you now subtract this half from 89MHz you get 75.5MHz and if you add this to 62MHz you also get 75.5MHz, so pretty close to 75MHz as nominal frequency.

    Just as an information on how to estimate the operation frequency when the value is not given.

    Dennis

  • 0 in reply to Dennis Eichmann
    Expert 1635 points
    Hello Shreyas-san, Dennis-san,

    Thank you for your answer.
    I think trying to use at 5 to 10MHz of frequency at 5V.
    I was able to confirm there is no problem.

    Best regards,
    Kato