Patent ID: 6949903

Claim:
A method of digitizing a voltage, comprising the steps of providing a capacitor ( 80 ) and an impedance, charging said capacitor, through said impedance, to a voltage value (Um) which is a function of the voltage to be digitized; ascertaining within which one of a plurality of voltage ranges said voltage value (Um) lies, each voltage range being defined by a respective first limit and respective second limit; providing a charge modification circuit containing an impedance, modifying, by means of said charge modification circuit, the voltage at the capacitor to the first limit, and ascertaining a first time interval needed therefor; modifying, by means of the charge modification circuit, the voltage at the capacitor from the first limit to the second limit, and ascertaining a second time interval needed therefor; calculating, based on the first time interval and second time interval, a digital value which serves as an indication of how much the voltage value (Um) at the capacitor differs from one of the two limits of the ascertained voltage range; further providing a resistor chain in the form of a series circuit of resistors connected via a connecting point, applying a substantially constant voltage to said resistor chain, successively comparing the respective potentials at the connecting points to the voltage value (Um) at the capacitor, in order to determine the first limit and the second limit of one of said voltage ranges, providing a resistor ( 94 ) for connection in parallel with said capacitor ( 80 ), testing whether the voltage value (Um) at the capacitor is greater than the potentials at all the connecting points of the resistor chain and, if so, completing a circuit path ( 78 , 94 , 96 , 54 ) including said resistor in parallel with the capacitor ( 80 ), in order to reduce the voltage value at said capacitor; and thereafter again comparing the potentials at the connecting points to the voltage value (Um) at the capacitor, in order to determine the first limit and the second limit.