Energy source switching device for supplying fail-safe circuit from external supply source or battery supply source has detector indicating presence or absence of external supply source for controlling switching circuit

摘要

The energy source switching device (320) has a detection circuit (322) coupled to the external energy supply source line (VCC), for providing a detector signal (DS) for a switching circuit (321) which connects the external energy source or a battery energy source to a fail-safe circuit (310), dependent on the presence or absence of the external energy supply source. An Independent claim for a fail-safe system with a continuous energy supply is also included.