The operating characteristics of a dynamic comparator is used to automatically change the resolution of a sloped or ramped analog-to-digital converter by switching the comparator on and off between first and second clock frequencies and comparing the amplitude of a sampled input signal against a ramp input signal. The first ROM bit has a first MOS transistor and a first block layer formed over a first region of the substrate. During a second mode when the alternator temperature is less than the threshold temperature and the engine is boosted, for example, the airflow from the airflow generating device is directed to assist purging of fuel vapors from the fuel vapor canister. The second lens group includes one or more cemented lens. The invention relates further to an apparatus for applying the method.