Prescaling devices are used when a high frequency signal, like a clock, needs to be reduced to a lower frequency to be utilized in other devices.  The prescalers can be designed to reduce this frequency by varying amounts, but it must be by some integer deviser and cannot be used with any other value.  When this conversion takes place, the output signals can be used to drive other components, which cannot operate, at the same high frequency that was initially clocked.  Usually prescalers are used to generate a reference clock for phase locked loops that function in a circuit.

 

These devices are designed using a variety of techniques involving logic gates and registers.  It uses different combinations of these devices allowing modifications of  high frequencies .  When the modified signal from a prescaler is fed into a counter or a timer, it acts as a new clock frequency for these devices.  A circuit can have many of these devices reducing a global clock into different frequencies depending on the downstream device’s needs.