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ADS8328: ADS8328 shorting AGND and DGND

Tom Franco
Prodigy 10 points
Part Number: ADS8328

Hi,
I'm using the ADS8328 in a design that has separated grounds at the client's request, and the ADC (ADS8327IBPW) seems to be shorting the analog and digital ground nets.

Based on the datasheet, the connections I'm using seem to be fine but perhaps I missed something, can anyone tell me if it's an IC issue or a schematic issue on my part?

Thanks in advance



  • 0
    TI__Mastermind 40860 points

    Hello Tom,

    Welcome to the TI E2E community!

    The AGND and BDGND are connected together inside the part with anti-parallel diodes (or sometimes called back to back).  This limits the absolute maximum voltage between these grounds from -0.3V to +0.3V to prevent these diodes from turning on.  If they do turn on and excessive current flows (in the 100mA range), then the part can be permanently damaged.

    If you have two ground planes on your board, then it is recommended to connect both grounds of the ADC directly to the analog ground as near the part as possible.  Please keep in mind that the digital lines are also protected with diodes to the power supply and ground pins, and must not exceed their ABS maximum value, which is -0.3V to +VBD+0.3V.

    Regards,
    Keith Nicholas
    Precision ADC Applications