AD7172 digital&analog ground connecting

Dear Analog,

I want to build ECG (electrocardiograph) circuit using your ADC AD7172. It has separate power inputs for analog circuit (AVCC, AGND) and for digital (SPI communication) circuit (DVCC, DGND). I am planning to use two completely separate power sources (Li Ion 18650 batteries) for analog (ADC & signal amplifiers) and digital (ADC & microcontroller & Bluetooth) circuits.

-----> QUESTION:

Do I need to connect the ground circuits of analog and digital circuits? I do not want to connect it due to high noises in digital circuit.

Please response me asap, so I can make myself proper PCB and start prototyping.

regards,

Winio

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  • 0
    •  Analog Employees 
    on Nov 25, 2015 6:23 PM over 5 years ago

    Hi Winio,

         The analog and digital supplies to the AD7172 are independent and connected to separate pins to minimize coupling between the analog and digital sections of the device.  As indicated on the datasheet, the PCB designed must have analog and digital sections separated and confined to certain areas of the board. You may also refer to the layout and schematic of the AD7172 for your reference that are available for download in the ADI web.

    AD7172-4 Evaluation Board | Analog Devices

    Regards,

    Jonathan

Reply
  • 0
    •  Analog Employees 
    on Nov 25, 2015 6:23 PM over 5 years ago

    Hi Winio,

         The analog and digital supplies to the AD7172 are independent and connected to separate pins to minimize coupling between the analog and digital sections of the device.  As indicated on the datasheet, the PCB designed must have analog and digital sections separated and confined to certain areas of the board. You may also refer to the layout and schematic of the AD7172 for your reference that are available for download in the ADI web.

    AD7172-4 Evaluation Board | Analog Devices

    Regards,

    Jonathan

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