All digital cameras are assigned an ADC number and it is given in the manufacturer's technical specifications for each model.
All DSLR and point-and-shoot cameras employ sensors that consist of pixels with photodiodes. These components convert the energy of photons into an electrical charge. That charge is converted to a voltage, which is then amplified to a level at which it can be processed further by the digital camera’s Analog to Digital Converter (variously called the ADC, AD Converter, and the A/D Converter).
The ADC is a chip inside your digital camera and its job is to classify the voltages of the pixels into levels of brightness and to assign each level to a binary number, consisting of zeros and ones. Most consumer digital cameras use at least an 8-bit ADC, which allows for up to 256 values for the brightness of a single pixel.