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Input transition rise or fall rate

Hanan Zeltzer
Prodigy 30 points

Hello,

I'm trying to understand this :

rise/fall time of an input is tr=freq/3 (as a rule of thumb), I have Vcc=3.3V so the rate is 10 nS/V.

as I understand it the minimum frequency would be 1/30nS = 33.3 MHz


do I understand it correctly ?

thank you

hanan

  • 0
    TI__Guru 64120 points

    Hi Hanan,

    If you are talking about the transition rate of the part, then it is talking of how fast the input edge rate of the signals must rise and fall to expect a stable output . It doesn't relate to frequency of operation . You can definitely have a very slow signal (in kHz ) but as long as the edges are transitioning fast enough , the device output will be stable and will not have any potential issues of oscillation .

    You can refer to the app note attached on effects of slow rising edge signals and possible solutions including Schmitt trigger circuits .