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ADS8556 Typical Offset Error

Vinicius Tin
Prodigy 10 points
Other Parts Discussed in Thread: ADS8556

Analog-to-digital converter ADS8556.

What does it mean the typical offset error of +/- 0.8 @ 25degCelsius found in the datasheet?

At lower or higher temperature what would be the offset error? Is there any linear correlation of the offset error with temperature? How/Can ambient temperature around the component change the offset error?

  • 0
    TI__Expert 6925 points

    Hi Vinicius,

    Welcome to the Precision Data Converters Forum.

    Offset and offset drift are due to process variations among many ADS8556, and it is a common non-ideality in semiconductor devices. The typical specs in the datasheet help to approximate the actual values during calibration of a specific converter. 

    The typical +/-0.8mV offset spec approximates the offset value that is expected if the converter is calibrated at 25degCelsius.

    For example, let’s imagine we calibrated three ADS8556 at 25degCelsius. One ADS8556 has -0.9mV offset, the second one has +0.4mV offset, and the third one has -0.1mV offset.

    After the converter is calibrated, the offset value changes somewhat linearly with temperature based on the typical +/-3.5uV/degC offset drift.

    For example, if the converter with -0.9mV offset @25degCelsius is recalibrated at +5degCelsius, its offset should approximate:
    -0.9mV + 4uV/degC*(5-25) degC = -0.980mV
    or
    -0.9mV  - 4uV/degC*(5-25)degC = -0.820mV
    The reason for the two values is that a converter can either decrease its offset with temperature or increase it. It all depends of the specific converter. For example, the converter used in Figure 15 of the datasheet decreases its offset with temperature.

    Let us know if this information helped or if you have any more questions.

    Thanks,
    Rafael