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TCA4311A: TCA4311 SCL low level have fluctuates

user4540890
Prodigy 10 points
Part Number: TCA4311A
Other Parts Discussed in Thread: TCA4311, TCA9511A,

We have a case that uses TCA4311. We get the test waveform close to TCA4311 and find that SCL low level have fluctuates, Sometimes it goes over 0.6V, and we're worried about triggering the trigger Rise-Time Accelerators. We change to PCA9511, and the fluctuates disappeared.

  • 0
    TI__Guru* 75011 points

    Hi User,

    Do you have an I2C device on SCL doing clock stretching and release? Just curious as to what is causing the low voltage here. I believe the problem is the buffer (4311A) being a bit slow to re-regulate itself back to the VOL+Vos causing the bump you're seeing.

    Two potential work arounds:

    1) make the pull up resistors weaker to lower the overshoot

    2) try replacing the TCA4311A with our TCA9511A. We remade the 9511A with a faster circuit than the 4311A so it should be able to minimize that overshoot. 

    -Bobby