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ADS7953: Channels Noise Issue

kieran frowen
Prodigy 10 points

Part Number: ADS7953

Tool/software:

Hello,

We are attempting to read 24 signals using a pair of ADS7953SBDBTR ADCs (U4 and U5) to read 24 signals (15 signals on on U4, 9 signals on U5).

The signals are sourced directly from 8 circuits, 3 signal outputs from each circuit (example of 1 circuit as shown below includes U12 current shunt monitor and U19 operational amplifier).

We see no noise on U19A-3. We see the below pattern on U19A-1 and the corresponding ADC_1 pin U4-21:

We see similar noise on other channels as shown below.

U20-1 / U5-23:

U21-1 / U5-28:

We have tried to test with ADC2 (U5) channels turned off, and we see reduced noise (but still noticeable) on U19A-1 and U4-21:

Is this noise expected, and is there anything we can do to reduce it (hardware changes etc)?

  • 0
    TI__Mastermind 20980 points

    Hi Kieran,

    The noise you are referring to is the large spikes, correct? It's possible that this could be due to the ADS7953 MUX switching, but you mentioned this still occurs when U5 is powered on, but inactive, yes?

    Are you able to isolate the source of the spikes by disconnecting the ADC inputs from the amplifier output, and probing the amplifier output? If this is an amplifier issue, I can refer you to our amplifiers team. 

    Regards,
    Joel