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AD7734: reference voltage other than 2.5V (ratiometric sensor)

Question asked by wildcard96 on Aug 29, 2012
Latest reply on Aug 29, 2012 by harryh

Hello,

 

i want to use the AD7734 ADC on a multifunctional pcb which should readout an ratiometric pressure sensor (0.5V-4.5V@5V supply V) aswell other signals like +-10V, 5V, +-5V.

 

The pressure-sensor has typical ratiometric output characteristics of 0.5V-4.5V @5Vsupply. The AD7734 has a standard reference voltage of 2.5V. 

 

My question is how to connect the sensor in the "right way" considering power supply rejection. The "normal" way (with ratiometric sensors) would be to connect the sensors supply voltage and the adc reference voltage. But iam not sure if this would be clever with the 7734.

 

The output code seems to be related to the input-range-register and not directly to the reference voltage!?

 

Thank you very much!

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