4.7.1 Input Offset Voltage Calibration Example

In this example, the OPA module is configured as an inverting amplifier. For improved precision, the module will periodically enter a calibration state where the OPA module must be set such that the input voltage, output voltage and gain are known exactly. To remove gain errors, the OPA module is put into Unity Gain. By measuring the difference between the input and the output with the ADC, the OPAxOFFSET register is stepped in increments, until the difference in value is within a user-set tolerance.

Figure 4-1. Normal Operation Mode
Figure 4-2. Calibration Mode
Important: The specific performance of calibration in-field is dependent on the environment and what the part is doing in the background at the time. It is unlikely to be as accurate or stable as a calibration in a controlled lab.
Figure 4-3. Calibration Flowchart