AD4003 negative output

Hi Rohit,

Can you clarify the input voltage on each of the IN+ and IN- pins?

Acknowledged that the differential voltage between them is 3V, but what are each pin's voltages with respect to GND?

Thanks,

Tyler

Hi Rohit,

Can you clarify the input voltage on each of the IN+ and IN- pins?

Acknowledged that the differential voltage between them is 3V, but what are each pin's voltages with respect to GND?

Thanks,

Tyler

Hi Tyler,

I have connected 3V on IN+ and 0V on IN-.

So I am seeing 3V as differential voltage.

Regards,

Rohit

Thanks Rohit.

You are using VREF = 5V, correct?

If so, then the Common Mode Input Range specification is being violated and would explain why the output code is invalid.

The common mode input range spec refers to the average voltage between IN+ and IN- pins. Nominally the common mode input voltage should be VREF/2. For 5V VREF this would bee 2.5V.

For the 3V and 0V configuration above, the common mode input voltage is 1.5V, which is out of the min/max spec range in the data sheet.

Achieving this common mode input voltage requirement can be done with devices such as fully differential amplifiers (see ADA4940, ADA4945, etc.)

Alternatively, the AD4002 is a single-ended version of the AD4003, where the IN- input can be tied to ground and there are no common mode input voltage requirements (since it's not a differential device).

Thanks,

Tyler

ok thanks I will check and solve this issue.