An optical sensor arrangement comprises a photodiode (11), an integrator (12) with an integrator input (15) coupled to the photodiode (11), a comparator (13) with a first input (18) coupled to an integrator output (16) of the integrator (12), and a reference capacitor circuit (14) that is coupled to the integrator input (15) and is designed to provide a charge package to the integrator input (15). In a start phase (A), charge packages are provided to the integrator input (15), until a comparator input voltage (VIN) at the first input (18) of the comparator (13) crosses a comparator switching point.