Patent ID: 7649489

Claim:
An apparatus for analog/digital conversion of a measurement voltage, including: an analog/digital converter, said analog/digital converter having: an integrating component with an operational amplifier, a resistor and a capacitor in a feedback loop, a clock signal generator which issues a system clock signal, wherein a reference voltage is applied to said inverting input of said operational amplifier and wherein the measurement voltage is applied to said non-inverting input of said operational amplifier, and wherein the capacitor is charged during a charging phase with a charging time and discharged during a discharging phase with a discharging time; a comparator downstream of said operational amplifier; a memory element downstream of said comparator; a time generator producing the charging time; a counter; and; a synchronizing element, wherein: at the inverting input of said comparator lies the output voltage of said integrating component and at the non-inverting input of said comparator lies the threshold voltage; said analog/digital converter at its output provides a pulse-width modulated output signal with period duration; said counter detects said period duration, of said pulse-width modulated, output signal; said reference voltage and said discharge time are constant, so that said input voltage is in reverse proportion to said period duration; said synchronizing element, which, at least within a predetermined measurement duration, synchronizes with a number of charging and discharging phases of said pulse-width modulated output signal with the cycle of said counter; switchover takes place through the synchronization with said counter at an output voltage which is above said threshold voltage; within the specified measurement duration a cycle of n measurement values occurs with the resolution of said counter; and said synchronizing element, said counter, said analog/digital converter and said time generator are synchronized with said system clock signal.