A method for operating a volatile memory supplied with a supply signal arranged either as a first supply signal of a first supply signal source or a second supply signal of a second supply signal source. If an available first supply signal is present it is used otherwise the second supply signal is used. The supply signal is supplied, based on a switch position of a switching element to the volatile memory. During a detected interrupted first supply signal, the switch position of the switching element is for a predetermined period of time such that the supply signal is supplied to the volatile memory. After expiry of the predetermined period of time, the switch position of the switching element is predetermined such that the volatile memory is decoupled electrically from the supply signal.