A method includes a first analog/digital conversion of an analog signal over m bits, with m less than n, associated with a first full-scale value, and a second analog/digital conversion of the analog signal over m bits associated with a second full-scale value 2n-m times bigger than the first. The two analog/digital conversions are carried out simultaneously and respectively delivering a first intermediate digital word of m bits and a second intermediate digital word of m bits. The method also includes a digital post-processing carried out after the two analog/digital conversions and generating an n-bit digital word starting from at least one of the two intermediate digital words extended to n bits and from at least one threshold digital indication representative of at least one threshold lower than or equal to the first full-scale value.