Apparatus for the analog/digital conversion of a measurement voltage with an analog/digital converter, which has an integrating component with an operational amplifier, a resistor and a capacitor in a feedback loop, wherein a reference voltage is applied to the inverting input of the operational amplifier and wherein the measurement voltage is applied to the non-inverting input of the operational amplifier The capacitor is charged during a charging phase of time length (t1) and discharged during a discharging phase of time length, wherein the analog/digital converter further includes a comparator connected downstream from the operational amplifier, a memory element connected downstream from the comparator, a time generator producing the charging time and a counter, the counter detects the edges, or the period length of the pulse-width modulated output signal provided by the A/D converter on the output, and a synchronizing element is provided, which synchronizes the edges of the pulse-width modulated, output signal with the clock pulse of the counter at least within a predetermined measurement duration.