PUMA 68F4006/A-70/90/12
ISSUE 4.2 : Nov 1998
Sector Erase
Sector erase is a six bus cycle operation. There are two "unlock"write cycles. These are followed by writing
the "Set-up" command. Two more "unlock" write cycles are then followed by the sector erase command. The
sector address (any address location within the desired sector) is latched on the falling edge of WE, while the
command (30H) is latched on the rising edge of WE. A time-out of 80us from the rising edge of the last sector
erase command will initiate the sector erase command(s).
Multiple sectors may be erased concurrently by writing the six bus cycle operations as described above. This
sequence is followed with writes of the sector erase command to addresses in other sectors required to be
concurrently erased. A time-out of 80us from the rising edge of the WE pulse for the last sector erase com-
mand will initiate the sector erase. If another sector erase command is written within the 80us time-out window
the timer is reset. Any command other than sector erase within the time-out window will reset the device to the
read mode, ignoring the previous command string (refer to Write Operation Status section for Sector Erase
Timer operation). Loading the sector erase buffer may be done in any sequence and with any number of
sectors (0 to 7).
Sector erase doesn't require the user to program the device prior to erase. The device automatically programs
all memory locations in the sector(s) to be erased prior to electrical erase. When erasing a sector or sectors
the remaining unselected sectors are not affected. The system is not required to provide any controls or
timings during these operations.
The automatic sector erase begins after the 80us time-out from the rising edge of the WE pulse for the last
sector erase command pulse and terminates when the data on D7 is "1" ( see Written Operation Status
Section) at which time the device returns to read mode. Data polling must be preformed at an address within
any of the sectors being erased.
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