DESCRIPTION
In SRAM mode, the memory operates as an ordinary static RAM. In non-volatile operation, data is transferred in parallel from SRAM to EEPROM or from EEPROM to SRAM. In this mode SRAM functions are disabled. The SRAM can be read and written an unlimited number of times, while independent nonvolatile data resides in EEPROM. Data transfers from the SRAM to the EEPROM (the STORE operation) take place automatically upon power down using charge stored in an integrated capacitor. Transfers from the EEPROM to the SRAM (the RECALL operation) take place automatically on power up. STORE cycles also may be initiated under user control via a software sequence. Once a STORE cycle is initiated, further input or output are disabled until the cycle is completed. Because a sequence of addresses is used for STORE initiation, it is important that no other read or write accesses intervene in the sequence or the sequence will be aborted. RECALL cycles may also be initiated by a software sequence. Internally, RECALL is a two step procedure.
Simtek
