Abstract: An automatic calibration system (10) for use with an A/D or D/A converter circuit (12). A reference (18) provides one or more reference signals (20) such that a controller (26) can determine whether the converter circuit (12) is within calibration, and direct a calibration unit (32) to adjust calibration as needed. Sets of calibration values appropriate for differed modes, ranges, and conditions are stored in a memory unit (28), for recall and quick pseudo recalibration. A triggering unit (30), which may optionally be programmable, can then inform the controller (26) when particular events occur. True calibration may then be performed based upon a reference signal (20), or pseudo recalibration may be performed based on calibration values recalled from the memory unit (28). Optionally, the controller (26) may interface with an external system, such as a personal computer having an electronic bus (60), and thus permit external control of both the calibration system (10) and the converter circuit (12).