Settling time

The settling time, engl. attack time ( rise time, settling time ) is the time interval required for a transient.

When switching an AC oscillation raises the steady state, the forced oscillation, only after a certain lapse of time. Also, any change in the excitation always occurs a balancing process ( transient), a transitional vibration - a transient free vibration. In linear oscillators, such as filters, transmission elements, rooms, etc., the transient effect of the forced vibration and free vibration can be assembled.

In theory, the transient process is never finished. But it is common to see the settling time as terminated when the signal amplitude exceeds ± its final value by more than 10 % of the difference between the initial and final value.

The transient process does not always start with a maximum change. Especially with pulses that only a relatively short time its maximum value hold (transients), one speaks of a rise time:

This is the time that elapses between the arrival of 10 % and 90 % of the maximum value of the rising edge. Accordingly, then, for the fall time:

Thus, the time that elapses between the achievement of 90% and 10 % of the maximum value at the trailing edge.