Can Cypress 3.0V FLASH memory with 'Low VCC Lock-out Voltage' operate at a core VCC level of 2.5V?
Answer: No, VCC=2.5 V is an out-of-spec operation for the 3.0-V parts. The allowed operating range is 2.7 V to 3.3 V; flash operations outside of this range are not allowed and give indeterminate results. Once VCC drops below the low-voltage lockout voltage, typically around 2.5 V, the flash is considered to be powered OFF, and must then go through a power-on reset (POR) to reinitialize the part. See the datasheet for the POR specifications for your part.