Schnittstellenschaltung mit Gleichstromwandler

摘要

In an interface circuit including a transmitting and receiving circuit which operates with an electric voltage supplying source composed of a DC/DC converter, the DC/DC converter includes a signal generation circuit generating a first signal having a first frequency, and a second signal having a second frequency lower than the first frequency, a comparator for comparing the elevated voltage with a reference voltage, and a selector for selecting one of the first and second signals and supplying the selected signal as the switching clock to the DC/DC converter. The selector is controlled by the comparator so as to supply the first signal as the switching clock to the DC/DC converter when the DC/DC converter is powered on, and to supply the second signal as the switching clock to the DC/DC converter when an absolute value of the elevated output voltage reaches the reference voltage.