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SN74LVC1G07: SN74LVC1G07 output strange peak issue

Part Number: SN74LVC1G07
Other Parts Discussed in Thread: SN74LVC1G17, SN74AUP1G17

Hi Sir,

We found there are some strange peak waveform in below waveform situation,

And it may cause some issue in customer side, could you please help to comments on it?

Or we can add any workaround solution to avoid the peak waveform?

Thanks

 

Diagram 1 is the measurement setup.

Channel 1: pin2(input)

Channel 2: pin4(output)

Channel 3: P3V3_ND1 (3.3 V power rail)

Channel 4: P3V3_AUX (3.3 V AUX power rail)

 

Waveform 1. When P3V3_ND1(CH3) turn on, SN74LVC1G07 output pin4 will output from low to high


 

 

Waveform 2. Zoom in from waveform1's SN74LVC1G07 output pin4 output from low to high

Before the SN74LVC1G07 output become stable high, it will have some peak waveform as below red circle when SN74LVC1G07 input is around 1.6V. and it will happened every time when output turn high from low.


 

 

  • Hi Anne,
    This is expected behavior from a CMOS device when slow inputs are used. The inputs are extremely slow in the scope shots above. Please see the FAQ on the topic here:

    The solution is to either provide faster inputs, or add a Schmitt-trigger buffer such as SN74LVC1G17 to eliminate the slow edge into the open-drain buffer.

  • Hi Maier,

    Thanks for the details explanation, for now our customer can't change the design that to fix it.
    Do we have any pin to pin solution with SN74LVC1G07 which as open drain buffer with Schmitt-trigger in side?
    How about SN74AUP1G17? is it suitable?
    Please advice,
    Thanks

    Anne Wu

  • Hi Anne,
    No we don't have any Schmitt-trigger input / open-drain output buffers in our portfolio.

    The SN74AUP1G17 is a Schmitt-trigger buffer, but it is not open-drain.

    Based on their schematic, they might be able to fix the issue by adding a capacitor at the output of the SN74LVC1G07, essentially filtering the output. The component R3407 is in the correct location, and could be replaced with a capacitor (perhaps 100pF or 220pF) to slow the output and smooth out the multiple triggers.