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TLV3601: Maximum Toggle Frequency

user4811888
Intellectual 510 points
Part Number: TLV3601
Other Parts Discussed in Thread: TLV9032

Hi expert,

I have seen this part has capbilibty of 325MHz toggle frequency due to short prop delay.

Could I learn that what could happen if frequency of input signal is higher than 325MHz?

That means if the input signal is changing repeatedly above and below the threshold, during prop delay, what is the output like?

  • 0
    TI__Mastermind 22260 points

    Thanks for your interesting question. When the input frequency gets higher and higher, the output pulses will start to shrink in amplitude (not reach logic high and low) and eventually the output will not change states any more. 
    Chuck

  • 0 in reply to Chuck Sins
    Intellectual 510 points

    Hi, Chuck

    Thanks for your answer. That means "delay" can only describe when toggle frequency is withis datasheet spec, otherwise it doen't show "delayed" charactertics but distored.

    However, could I be greedy to know what if a one-pulse (NOT repeated) with its width shorter than prop delay, is sent into a comparator?

  • 0 in reply to user4811888
    TI__Mastermind 22260 points

    Another good question. Your assessment of prop delay is correct in part 1 of your post and your new question is related to our spec called min pulse width. This is your one shot scenario and we look for when the output pulse width decreases to 90% of the input pulse width. Likewise, as the input pulse width narrows so does the output until eventually it doesn’t exist. 
    Chuck

  • 0 in reply to Chuck Sins
    Intellectual 510 points

    thanks, it sounds reasonable but could you please recommend one part number which has spice/TINA model, that I can understand it in deep via simulation?

  • 0 in reply to Chuck Sins
    Intellectual 510 points

    I just figured out one figure to show what I'm confused about, the red shadow represents prop delay(rising and falling are assumed equal here), the green represents min pulse width you just explained.

    I go through datasheet of TLV3601, the prop delay is ~2.5ns and min pulse width is ~1.25ns typically, it matches below. Is the OUT correct?

    THe most confusing point is during rhe second rising, IN+ rises above VT+ again but still during prop delay of falling below VT- last time.

  • 0 in reply to user4811888
    Guru 136860 points

    Hi,

    there is a Spice model on the product's website:

    https://www.ti.com/product/TLV3601#design-tools-simulation

    But I doubt that your far going question can be simulated in fully detail. So why not checking out the behaviour of TLV3601 in a test circuit?

    Kai

  • 0 in reply to kai klaas69
    Intellectual 510 points

    Hi Kai,

    TLV9032.TSC

    I just used attached TINA simualtion of TLV9032 with 30MHz input square waveforms much higher than 3MHz it claims in datasheet, the output only acts as ideal delay unit of prop delay, it's clealy far away from real circuit. I doubt that the accuracy of TINA and spice model is not so good for high frequency operation.  

  • 0 in reply to user4811888
    TI__Mastermind 22260 points

    Sorry, but as Kai was eluding to, our models are macro models and do not simulate these behaviors. What you are seeking would essentially be a transistor level model which isn’t provided. We do have some nice EVMs for tlv3601 if you wish to experiment. 
    Chuck