Semiconductor device having multiple power-supply nodes and capable of self-detecting power-off to prevent erroneous operation

摘要

A potential detection portion generates from a power-supply potential of 3.3V a reference potential Vref lower than 1.5V, and compares reference potential Vref with a potential of a power-supply line of a 1.5V system to detect a power-off. An output of potential detection portion is provided to a gate of an N-channel MOS transistor via a level conversion circuit. N-channel MOS transistor fixes an output of an internal circuit that operates by a power supply of the 1.5V system.