The analog-to-digital converter comprises a first stage in which a voltage to be converted is applied to the input of a first comparator. The first comparator delivers a first digital result representative of the comparison between the voltage to be converted and the reference voltage on a first digital output. The first digital output is connected to means for calculating a first intermediate voltage. A second comparator compares the first intermediate voltage with the reference voltage and delivers a second digital result on a second digital output terminal. The digital output terminal is connected to second means for calculating a residual voltage according to the voltage to be converted, the first and second voltages and the first and second digital results.