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PCA9515A: PCA9515A I2C IC waveform questions

Red Yen
Expert 4350 points
Part Number: PCA9515A
Other Parts Discussed in Thread: PCA9515

Hi Support team 

At present, when used PCA9515 I2C IC, you can find that the SDA / SCL signal has two stages in the low level.

In SDA, there is a description in the specification, but SCL does not mention that there will be this phenomenon....

is this normal phenomenon and how to avoid that?
Any side effect will it have on communication?

  • 0
    TI__Guru 60850 points
    Hello Red Yen,

    "n SDA, there is a description in the specification, but SCL does not mention that there will be this phenomenon"
    SDA and SCL are built/designed the same way. The SCL is specc'd to have a typical of 0.52V for VoL in section 6.4 of the datasheet. If you use a strong pull up resistor then this number can be larger.

    "is this normal phenomenon and how to avoid that?"
    This is normal, this device was designed to have this as it prevents the device from locking itself low.

    "Any side effect will it have on communication?"
    The only downside I can think of is the device just has a larger VoL. If your VoL is larger than ViL then you may not be able to register the logic low.

    Thanks,
    -Bobby