How is Sector Erase Time, including pre-programming, determined on the S29JL032J device?
Determining overall Sector Erase Time is simply Sector Erase + Pre-programming.
However, keep in mind that the overall Sector Erase time is dependent on the data pattern programmed into the main memory array of the S29JL032J.
For example, if there are many unprogrammed (erased) bytes or words, more pre-programming time is required to pre-program erased bytes or words from ONE's to ZERO's. These same bytes or words bits are then "erased" back to ONE's. If there are many programmed bytes or words, then less pre-programming is required. Programmed bytes or words (ZERO's) are simply "erased" to ONE's.
Note that the Sector Erase algorithm has a pre-programming sub-routine which operates identical to that of BYTE or WORD programming commands. The Sector Erase algorithm erases in BYTE or WORD mode is dependent on whether the physical BYTE# pin is connected logic low (x8) BYTE mode, or logic high (x16) WORD mode.