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AM3352 MII signal overshoot

Nomo
Guru 16800 points
Other Parts Discussed in Thread: AM3352

Hello,

In very short time, the overshoot occurs on AM3352's MII signal (pr1_mii0_txen).
And, the voltage violates the absolute maximum ratings a little.
However there is no ability to modify the overshoot by hardware, it seems that the overshoot is occurred by the AM3352's drive strength.
I know that pr1_mii0_txen's drive strength can't change.
Does the overshoot invoke the critical problem?

Best Regards.

Nomoto

  • 0
    TI__Guru**** 393215 points

    Hi Nomoto-san,

    How big is this overshoot? Can you post a screenshot?

  • 0 in reply to Biser Gatchev-XID
    Guru 16800 points

    Hello Biser-san,

    Thank you for your reply.
    I'll attach a wave form.

    Best Regards.

    Nomoto

  • 0 in reply to Nomo
    TI__Guru 62825 points

    What parameter in the AM335x data sheet were you concerned this overshoot violates?

    The only Absolute Maximum parameter in the data sheet that applies to IO signals is the "Transient Overshoot and Undershoot specification at IO terminal" which is defined to be "25% of corresponding IO supply voltage for up to 30% of signal period".

    It does not look like this overshoot exceeds AM335x data sheet limits.

    Based on the above waveform the overshoot appears to be about 0.4 volts which is only 12% of the 3.3 volt IO supply voltage and the duration is about 12.5ns (one tenth of scope display) which means it is less than 10% of the signal period since the signal period is greater than the what is captured on the scope display.

    Regards,
    Paul