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ADS8665: Internal biasing voltage

Part Number: ADS8665

Hi Team,

Please let me understand what the internal biasing voltage of ADS8665 is.

The ADS8665 datasheet, page 21, 7.3.1 Analog Input Structure, has the following description for the case of the analog input  pin floating,

  "If the analog input pin (AIN_P) to the device is left floating, the output of the ADC corresponds to an internal biasing voltage. The output from the ADC must be considered as invalid if the device is operated with floating input pins. This condition does not cause any damage to the device, which becomes fully functional when a valid input voltage is applied to the pins."

I understand that the internal biasing voltage is "VB" of Figure 46. Simplified Analog Front-End Circuit Schematic, VBIAS of 7.2 Functional Block Diagram.
Is the internal biasing voltage the same as the 4.096-V reference voltage?
Thank you.

Best Regards,

Koshi Ninomiya

  • Hi Koshi,

    The bias voltage changes with different input range configuration, the specific voltage can be found in Electrical Characteristics 6.5 specified in page 5 of datasheet, below is a snapshot, the voltage is around 2.5V for +/-3Vref range as an example. Notice that this bias voltage does not have any impact when your input signal is available.

    Regards,

    Dale