DDC232 offset

Edward,

The DDC products are now being supported in the Medical/High Reliability Forum.  I will move your post to their forum.

Best regards,

Bob B

Hi Edward,

0.4% is the requirement for Negative Full Scale Range. The typical offset error (tolerance) is +/- 200 ppm of FSR and the maximum offset error is +/- 1000 ppm of FSR.

-Yvette

Yvette

This refers to the offset of the input integrating amplifier. I am referring to the Data Format on page 20 of the datasheet. It says "An
offset is included in the output to allow slightly negative inputs (for example, from board leakages) from clipping the reading. This offset is approximately
0.4% of the positive full-scale.

I want to know tolerance of this,

Brgrds

Edward

Hi Edward,

How are you?

For the offset variation (i.e. offset error) for DDC232, please refer to Page# 3.

Offset variation typically is within +/- 200ppm (i.e. +/- 0.02%)

and its Maximum is within +/-1000ppm (i.e. +/- 0.1%)

This is the allowance (tolerance) of offset variation for all the 32 channels.

Thanks and Best Regads,

Chen

Hi Edward,

The tolerance I mentioned before is correct. The tolerance is true for all percentages of FSR.

If we consider format1 (20 bit output word), full scale range = 2^20 – 1 [codes]. Then, .4% of FS ≃ .003955 of FS ≃ .003955 * (2^20 – 1) ≃ 4147.114 [codes]. Note I pulled the .003955 value from page 20 of the data sheet. The DDC232 actually has a built in offset of 4096 codes (not 4147.114) at 0% FSR to account for the slightly negative inputs.

Now, consider the tolerances from page 3 of the data sheet [typical offset error (tolerance): +/- 200 ppm of FSR and the maximum offset error: +/- 1000 ppm of FSR.] If we look at the typical offset error values, the offset values at 0% FSR will span (4096 – 200 to 4096 + 200) which gives 3896 to 4296 codes.

Regards,

Yvette