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ADS7830: About the voltage for ACK.

Kengo.Y
Guru 10385 points
Part Number: ADS7830
Other Parts Discussed in Thread: PCA9515

Hi team,

Could you tell me about ACK.

The ACK from ADC7830 floats from about 500 mV.

Why does GND float as much as 500 mV?

Sincerely.
Kengo.

  • 0
    Guru 10385 points

    Hi team,

    I got a waveform from my customer.
    Could you check it?

    ADS7830_Waveform.pdf

    Sincerely.
    Kengo.

  • 0 in reply to Kengo.Y
    TI__Mastermind 24940 points

    Hello, 

    Looking at the document, my understanding is that Ch1 and Ch3 should be the same. but it seems that it is not, the states of the SDA lines are different across the PCA9515.

    Does any other bit also experience a low pull down, or just the acknowledge?

    further more,  it seems as Ch3 low voltage is continuing to increase, and the ACK bit seems to be higher. this leads me to believe that there is some time of interaction in the digital line. If communicant continued, I believe the entire bus would eventually be at a higher ground voltage than desired.

    if the PCA9515 is removed, is this still seen?