It converts the analog signal to digital data

Symbolic representation of analog to digital converter (ADC) is shown below

In addition to the analog I/p voltage VA, the ADC block has a ref voltage VR I/p and two control lines soc and EOC. The soc(start of conversion)I/p is used to start the A to D conversion where as EOC (End of conversion ) o/p goes high to indicate that the conversion is complete

At t=$t_{0}$ soc signal is given to the ADC & at t=$t_{1}$

We get EOC o/p .The time difference between these two instants is called as “conversion time “