ISSUE 4.3 : November 1998
PUMA 68F16006/A-80/90/12/15
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 (data) is latched on the rising edge of WE. A time-out of 50us 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 desribed above. This
sequence is followed with writes of the sector erase command 30H to addresses in other sectors required to
be concurrently erased. A time-out of 50us from the rising edge of the WE pulse for the last sector erase
command will initiate the sector erase. If another sector erase command is wriiten within the 50us 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 50us 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.
Erase Suspend
Erase suspend allows the user to interupt the chip and read data (not program) from a non busy sector while it
is in the middle of a sector erase operation, which may take several seconds.
The command can only be used during sector erase operation and otherwise will be ignored. The erase
suspend command B0h is also allowed during the Sector Erase Operation that will include the sector erase
time out period after the sector erase commands B0h. Writing this command during the timeout will result in
immediate termination of the time out period and any subsequent writes of Sector Erase Command will be
taken as Erase Resume.
To suspend the erase operation and go into erase suspend mode (pseudo read mode) requires between 0.1
and 10µs, during which time the user can read from a sector that is not being erased. The toggle bit stops
toggling when the device enters pseudo read mode and an address of a sector not being erased must be used
to read the toggle bit.
After the user writes the erase suspend command and waits until the toggle bit stops toggling, data reads from
the device may then be performed. After an Erase Resume command the internal counters, which are used to
count the high voltage pulses required to program or erase, are reset. The Exceed Time limit flag D5 is set if
the count exceeds a certain limit. (The resetting of the counters is necessary as the erase suspend command
can potentially interupt the high voltage pulses.)
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