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AD7329 reference voltage

Hi all!

I'd like to use the AD7329 in my design.
  From what I understand, a 2.5V reference can be used to measure up to ±10V and a 3V reference can be used to measure ±12V at the analog input pins.
  Reading through the datasheet, it's not clear to me what reference voltage is needed when I want to be able to measure ±16.5V at the analog input pins.

Thanks in advance!

Parents
  • Hi, 

    The AD7329 has 4 options for input ranges and these are the 

    +/-10V, +/-5V , +/-2.5V and 0 to 10V. These ranges have a typical voltage reference of 2.5V. The highest input range of +/-10V is based on a maximum range of 4xVREF. If the VREF is changed to 3V, the maximum full-scale input range can be stretched to 12V. Note that the VREF is only specified for up to 3V only. Beyond this value may lead to errors in the ADC and it is not recommended to operate above the 3V VREF.

    Regards,

    Andrei

Reply
  • Hi, 

    The AD7329 has 4 options for input ranges and these are the 

    +/-10V, +/-5V , +/-2.5V and 0 to 10V. These ranges have a typical voltage reference of 2.5V. The highest input range of +/-10V is based on a maximum range of 4xVREF. If the VREF is changed to 3V, the maximum full-scale input range can be stretched to 12V. Note that the VREF is only specified for up to 3V only. Beyond this value may lead to errors in the ADC and it is not recommended to operate above the 3V VREF.

    Regards,

    Andrei

Children
  • Hi,

    Thanks for your reply! Slight smile

    I understand measuring higher voltages than 12V can result in measurement errors.

    This is okay for me, I will try to filter this in software!

    The absolute maximum ratings for an analog input is 16.5V (VDD+0.3V), and for the REF it's 7V (VCC+0.3V).

    Do I have to apply the maximum REF voltage to be able to measure 16.5V at the analog inputs?

    And if I want to measure voltages higher than 10V, do I still leave the range registers on the 10V setting?

    Regards,

    eutim