Threshold level calibration method and apparatus

摘要

A threshold calibration method and apparatus calibrates a reference voltage representing a selected threshold and compares the reference voltage with a measurement voltage representing a variable parameter to indicate the condition of the variable parameter. The reference voltage is set by causing the variable parameter to assume a predetermined high value and adjusting a first potentiometer to provide a first calibration voltage equal to the measurement voltage representing the high value. The variable parameter is then caused to assume a predetermined low value and a second potentiometer is adjusted to provide a second calibration voltage equal to the measurement voltage representing the low value. The first and second calibration voltages are then combined using passive resistive components to provide a reference voltage representing the selected threshold.