Telecommunications equipment is often subjected to environmental and other electrical stresses such as lightning strikes, equipment faults, and capacitor-bank switching. These events can cause input-voltage transients of up to 100 V for durations of 10 ms. Today’s isolated DC/DC power supplies must have a very good control method (or voltage feed forward) to limit the magnitude of the output-voltage undershoot and overshoot caused by an input-voltage transient.