DATENSCHREIBREGELUNGSMITTEL

摘要

The means is of a data protecting means (310) for preventing erroneous writing in a data-holding circuit (307). A data protecting circuit (311) receives a data protect set/release select signal Sa outputted from a processor (330) and starts a second clocking means (316). When the second clocking means (316) measures a period T2, the data protecting circuit (311) detects the level of a chip select signal CS produced by a power source monitoring circuit (320) and sends a data protecting signal DP corresponding to the level of the signal Sa to a data-holding circuit (307) only when a main power source (305) is judged to be normal.