reference of AD9245

We use AD9245 to sample the signal detect single end amplifier with output voltage from 0 to 2 volts.  We connect this output to Vin+. My question is that should we connect the Vin- to ground or to a voltage reference of 1 volt. If we connect the Vin- to ground, the differential input of AD9245 will be from 0 to 2 volts. If we connect the Vin- to 1 volt reference,  the differential input of AD9245 will be from -1 to 1 volt.  Could you please tell us which solution is right or both are right?

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    we follow this setting, and 1V give VIN- to have 0-2V input as ±1V digital output for servo control.

    target is to match VIN+=VIN- as 1V. 

    by now we get +60mV different between VIN+ with VIN-  when servo is working(VIN+ always bigger than VIN-).

    is that means the VIN+ reading is 6% less than real voltage?

    if I change target half, I will have +30mV VIN+ bigger than VIN-.

    because the code only check AD9245 is 0 or not, reduce output when bigger than 0 and increase output when less than 0. 

    both VIN+ and VIN- has 33 ohms input resistor.

    VREF connect to VIN-, there is 1K to ground before 33 ohm.

    input through 33 ohm to VIN+, no resistor between it with ground.

    could you please help check if any connection worn?

    thanks again.

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  • thanks

    we follow this setting, and 1V give VIN- to have 0-2V input as ±1V digital output for servo control.

    target is to match VIN+=VIN- as 1V. 

    by now we get +60mV different between VIN+ with VIN-  when servo is working(VIN+ always bigger than VIN-).

    is that means the VIN+ reading is 6% less than real voltage?

    if I change target half, I will have +30mV VIN+ bigger than VIN-.

    because the code only check AD9245 is 0 or not, reduce output when bigger than 0 and increase output when less than 0. 

    both VIN+ and VIN- has 33 ohms input resistor.

    VREF connect to VIN-, there is 1K to ground before 33 ohm.

    input through 33 ohm to VIN+, no resistor between it with ground.

    could you please help check if any connection worn?

    thanks again.

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