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Original question:

P82B96: About the solution to correct VOL level mismatch

P82B96: Inquiry Regarding the Extended Falling Time After Connecting P82B96 with TCA9803

Wang MINT
Prodigy 10 points
Part Number: P82B96
Other Parts Discussed in Thread: TCA9803,

Tool/software:

Hi support team,

As shown in the figure, when I connected the TCA9803 to PB2B96 in order to reduce the output voltage (VOL), I observed that the falling time of the SDA signal from the TCA9803 output increased, and the output level of PB2B96 was also pulled down to ground.

What could be the cause of this issue? Are there any ways to avoid this problem?

I appreciate if you could give me some advice.

Best regards,

MINT

  • 0
    Guru 279750 points

    This is a consequence of using two buffers, and of the P82B96 having a voltage offset on the SX/SY pins. Why do you think that it is a problem?

  • 0
    TI__Mastermind 31353 points

    Hi MINT,

    This looks like expected behavior. The P82B96 has a static voltage offset of ~0.88 V. It drives strongly to GND and then goes to the steady state output low voltage of 0.88V. 

    As to why the fall-time changed on the output of the TCA9803, what was it before? 

    The I2C waveforms look fairly clean. Are you tracking bit errors? 

    Regards,

    Tyler