# cn0209 bipolar unipolar

Dear sir,

i am using cn-0209 eval board i want to test unipolar and bipolar measurement ...

is the external circuit same for bipolar and unipolar voltage measurement?

is there any change change in register setting for ad7193?

actually in adc there is unipolar and bipolar bit change for corresponding measurement?

when i measure the circuit for -10 v get the circuit out(ad8275 out) 0v and 10v get the circuit out(ad8275 out) 4.5v

means it always make bipolar to unipolar at adc input...

so what change to make bipolar measurement and unipolar.

in cn0209 if we consider only unipolar but if it goes below 0v the value must be 0 how can make it..

please explain about voltage measurement for bipolar and unipolar and adc register change for unipolar and bipolar

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• Hi Francis,

The CN0209 can accept up to ±10V signals, there is no need to change any settings in the AD7193 for different ranges.

The output of the AD8275 should be 4.5V/2 = 2.25V for a 0V input. For a -10V input the gain of the AD8275 is 0.2, so the output should be 2.25+(-10)*0.2 = 0.25V.Similarly for a +10V input the output should be 2.25+(10)*0.2 = 4.25V.

Yes, the AD8275 is configured to configured to perform a differential to single ended conversion as well providing a gain of 0.2. The video at this link explains the device operation a bit more.  This single ended voltage is measured referenced to AINCOM of the AD7193.

Regards,

Derrick

• Hi Francis,

The CN0209 can accept up to ±10V signals, there is no need to change any settings in the AD7193 for different ranges.

The output of the AD8275 should be 4.5V/2 = 2.25V for a 0V input. For a -10V input the gain of the AD8275 is 0.2, so the output should be 2.25+(-10)*0.2 = 0.25V.Similarly for a +10V input the output should be 2.25+(10)*0.2 = 4.25V.

Yes, the AD8275 is configured to configured to perform a differential to single ended conversion as well providing a gain of 0.2. The video at this link explains the device operation a bit more.  This single ended voltage is measured referenced to AINCOM of the AD7193.

Regards,

Derrick

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