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SN74LV14A: can support 12.5M frequency?

Randy Wang
Intellectual 1705 points
Part Number: SN74LV14A
Other Parts Discussed in Thread: SN74LV163A

Hi Team

  My customer is using SN74LV14A for 12.5M signal inverter, but the output signal looks not very well, I'm wondering if SN74LV14A can support such high frequency? thanks. 

  • 0
    TI__Guru* 96591 points
    Hi Randy,

    The SN74LV14A can definitely handle 12.5 MHz. The signal integrity as shown on an oscilloscope will have many factors - including cable type/length, probe type, loading, among others.

    The signal shown looks pretty good to me - the edges are fast, there's limited ringing, and over/undershoot appears quite controlled. To see the most accurate representation of what is in the circuit, we recommend using a differential probe to measure the signal directly at the device output (this eliminates many of the aforementioned factors).

    Is there a particular concern with this waveform? Can you verify the test setup?
  • 0 in reply to Emrys Maier
    TI__Intellectual 1705 points

    Hi Emrys

      Thanks for your comments, we're verify the test setup right now, one more thing is, how to identify the maximum frequency of SN74LV14A? Datasheet didn't have kind of this information. thanks. 

  • 0 in reply to Randy Wang
    TI__Guru* 96591 points
    If you want to verify on the bench, the best method is to attach a pulse generator to the input and crank up the frequency until the output can't sustain VOH/VOL specs given in the electrical characteristics table.

    We typically spec the maximum frequency for logic gates at the maximum for a clocked device in the same technology family. While this isn't exact, it should give you a reasonable estimation of the max frequency. In this case, the SN74LV14A is an 'LV-A' family device, so I pulled up the SN74LV163A datasheet and found fmax(min) = 80 MHz and fmax(typ) = 160 MHz at 15pF load.

    Since the SN74LV14A is much simpler than the SN74LV163A, it stands to reason that it will operate beyond these frequencies.