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ADS8681EVM-PDK: so

Part Number: ADS8681EVM-PDK

Tool/software:

hi SIR

question 1:

I Got the ADS8681EVM & test the evb done, another plan is verity the ADS8699 performance.

may I exchang the ADS8699 to the ADS8681EVM?

ADS8681, ADS8699 only bit different?

question 2:

after change the ic, any firmware or hardware need modify?

question 3

I add the AC couple, that is right? as below figure

 :

question 4:

  1. below is the bandwidth of ADS8699, May I adjust the bandwidth?

         2. how the hold the 15kHZ Maintain, no attenuation

question 5:

5. if you have any solution which bandwidth is wide than ADS8699, others is same

thanks

  • Hi Alex,

    A1 and 2.)  Yes, you can swap out ADS8681 for ADS8699, however the SW and GUI is only configured for 16-bit data.  I'll check, but I don't believe we have a version of the GUI that supports 18-bits.  

    A3) What voltage range are you looking at?  Why are you looking to do an AC coupled input?

    A4 and 5) No, you cannot adjust the internal LPF frequency, it is fixed at 15kHz.  There is a recently released ADS8681W which has a wider bandwidth (450 kHz) LPF, also fixed.

  • A3) What voltage range are you looking at?  Why are you looking to do an AC coupled input?

    Input range:+/-10V 和 +/-2.5V, 

    input have the DC offset, we would like to in serial to a cap to reduce the DC  value

    after Add the cap, Will it cause sampling error to adc?

  • No, it won't impact the ADC sampling.  You won't need the cap on the AIN_GND side.

  • hi Tom

    when I remove the cap in the ADIN_GND, I will get the offset value, 

    If add the cap in ADIN_P  and  ADIN_GND, The offset is Zero

    Did you have any AC couple guide for me?

    thanks

  • Hi Alex,

    I don't have anything specific on AC coupling.  If adding the cap to AIN_N gives you the result you are looking for, you can leave it in the circuit.