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Using the ADXRS620 with a Vratio voltage lower than AVcc

Question asked by Embedded182 on Jul 23, 2012
Latest reply on Aug 2, 2012 by Embedded182

Hi,

    I want to use the ADXRS620 with an ADC with an Full Scale output voltage of 2.5v.

As far as I can see, there are two ways I can do this.

  1. Put a voltage divider on the RATE_OUT to divide the FS down to 2.5 before connecting to the ADC.
  2. Drive Vratio from a 2.5v reference source and connect RATE_OUT directly to the ADC input.

 

As I already have a 2.5v reference in my application, option 2 seems the better choice as it save 2 resistors. However, the datasheet doesn't give me enough information to be sure this is the best choice.

Can you answer the following questions for me please?

  1. Will the ADXRS620 operate correctly if Vratio is 2.5V?
  2. How is the accuracy of the part changed if I use a 2.5v Vratio?
  3. How much current does the Vratio pin draw at 2.5v?
  4. Is this a steady state current or could connecting the Vratio pin to my clean 2.5v reference cause noise issues for other ADC channels which share this reference?

 

Thanks

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