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two questions for AD7266

Question asked by qd0090 on Nov 21, 2013
Latest reply on Nov 28, 2013 by jcolao

hi everyone, i have two questions for AD7266

question1:

  in the datasheet of  AD7266, it mentioned in  "product highlight" that :The AD7266 offers both a standard 0 V to VREF input range and a 2 × VREF input range

  so, in the case of vdd=3.3V, use internal 2.5V REF input range is configed to  2 × VREF, can the ADC provide a 0~3.3V input voltage convert range?

  in my design,  i have a 0.3~3.0V analog voltage needs to be converted, but the PCB board only have 3.3V VDD, so i can not use ADC that needs 5V VDD.

question2:

the datasheet mentioned the input range:,in pseudo differential mode "The AD7266 can have a total of six pseudo differential pairs. In this mode, VIN+ is connected to the signal source that must have an amplitude of VREF (or 2 × VREF, depending on the range chosen) to make use of the full dynamic range of the part."

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   does it be ok if i have a Vin-=1.25V and VIN+ has a commone voltage 1.25V and 0.7V amplitude? VIN+ range is 1.95~0.55. will this affect the accuracy of the ADC?(since the datasheet says "must have an amplitude of VREF (or 2 × VREF, depending on the range chosen) to make use of the full dynamic range of the part")

 

 

 

  thank you!

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