AD7707 and reference voltage

I want to use AD7707 for temperature measurement ("RTD.gif") and analog signals 0-5V and 0-10V ("Analog In.gif ").

What to use for reference voltage:
- AD780 ("REF.gif")
- resistor 6.25 kOm

If I use a resistor of 6.25 kOm, how can it affect the measurement of analog signals?

 

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  • Hi,

    I would suggest to use a stable external reference voltage for your other inputs. So make sure that your current source is stable if you intended to use the same reference voltage for this. Any variation in reference voltage may results errors or variations in your measurements. So if you could provide a low noise, more stable voltage reference, it would be better. REF192 is a good choice for reference voltage. Do you really want to use AD7707? We have new products which have internal excitation current as well as internal reference voltage that may suite your application. You may want to consider using AD7124 and AD717x series.  

    Thanks,

    Jellenie

Reply
  • Hi,

    I would suggest to use a stable external reference voltage for your other inputs. So make sure that your current source is stable if you intended to use the same reference voltage for this. Any variation in reference voltage may results errors or variations in your measurements. So if you could provide a low noise, more stable voltage reference, it would be better. REF192 is a good choice for reference voltage. Do you really want to use AD7707? We have new products which have internal excitation current as well as internal reference voltage that may suite your application. You may want to consider using AD7124 and AD717x series.  

    Thanks,

    Jellenie

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