Nonvolatile semiconductor memory with controlled supply of boosted voltage

摘要

A semiconductor memory is designed to avoid a situation that the program cannot escape from a writing operation, and the writing operation can be promptly finished according to the level of an external source voltage. This semiconductor memory has a voltage detecting circuit for detecting whether a boosted voltage has reached a predetermined potential and a timer capable of counting predetermined time. A control circuit applies the boosted voltage to a selected memory cell when the voltage detecting circuit detects that the boosted voltage has reached the predetermined potential or when it is detected that the predetermined time has elapsed since the start of the boosting operation.