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AD7780 non-ratiometric usage

Question asked by bellkev on Sep 3, 2013
Latest reply on Sep 3, 2013 by JohnnyG

Hello,

 

I'm wanting to use the AD7780 in a non ratiometric configuration which means that Vref does not equal AVDD. Page 3 of the datasheet says that the  Differential input Voltage Range = +/-Vref / gain when the assumption is that Vref = AVDD. Does this equation still apply in the configuration i want to use it?

 

AVDD = 5V

Voltage REFIN = 2.5V (REFIN+ = 2.5V, REFIN- = GND)

 

According to the equation above the input would be limited to 19.5mV differential input voltage at 128 gain. I'm wondering if the input range is actually defined by AVDD?

 

Thanks,

Kevin

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