摘要 |
PURPOSE:To perform a store operation without erasing electrons from a floating gate when the electrons are to be injected into the floating gate before/after the store operation, by connecting a control terminal with a first high voltage terminal CG through which the electrons are injected into the floating gate and then connecting the control terminal to a transistor. CONSTITUTION:In the case of a store operation in which information of an SRAM is transferred to an EEPROM, a high voltage VCG is applied to a first high voltage terminal CG15 after a potential on a connection point Q6 is defined to be on an H or L level. When the state of the connection point Q6 is on an L level, a Fowler-Nordheim current flows from an ERS terminal 16 to a floating gate 14, so that the floating gate 14 is negatively electrified. After electrons can be sufficiently injected into the floating gate 14, a high voltage VERS is applied to a second high voltage terminal ERS 15. When the state of the connection point Q6 is on an H level, the Fowler-Nordheim current flows from the floating gate 14 to the ERS terminal 16, and the electrons are erased from the floating gate 14, so that the floating gate 14 is positively electrified. |