MBM29LV400TC-70/-90/-12/MBM29LV400BC-70/-90/-12
Chip Erase
Chip 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 chip erase command.
Chip erase does not require the user to program the device prior to erase. Upon executing the Embedded Erase
Algorithm command sequence the devices will automatically program and verify the entire memory for an all
zero data pattern prior to electrical erase (Preprogram function). The system is not required to provide any
controls or timings during these operations.
The automatic erase begins on the rising edge of the last WE pulse in the command sequence and terminates
when the data on DQ7 is “1” (See Write Operation Status section.) at which time the device returns to read the
mode.
Chip Erase Time; Sector Erase Time × All sectors + Chip Program Time (Preprogramming)
Figure 21 illustrates the Embedded EraseTM Algorithm using typical command strings and bus operations.
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=30H) is latched on the rising edge of WE. After time-out of 50 µs from the rising edge of the last sector
erase command, the sector erase operation will begin.
Multiple sectors may be erased concurrently by writing the six bus cycle operations on Table 7. This sequence
is followed with writes of the Sector Erase command to addresses in other sectors desired to be concurrently
erased. The time between writes must be less than 50 µs otherwise that command will not be accepted and
erasure will start. It is recommended that processor interrupts be disabled during this time to guarantee this
condition. The interrupts can be re-enabled after the last Sector Erase command is written. A time-out of 50 µs
from the rising edge of the last WE will initiate the execution of the Sector Erase command(s). If another falling
edge of the WE occurs within the 50 µs time-out window the timer is reset. (Monitor DQ3 to determine if the
sector erase timer window is still open, see section DQ3, Sector Erase Timer.) Any command other than Sector
Erase or Erase Suspend during this time-out period will reset the devices to the read mode, ignoring the previous
command string. Resetting the devices once execution has begun will corrupt the data in the sector. In that
case, restart the erase on those sectors and allow them to complete. (Refer to the 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 10).
Sector erase does not require the user to program the devices prior to erase. The devices automatically program
all memory locations in the sector(s) to be erased prior to electrical erase (Preprogram function). 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 50 µs time out from the rising edge of the WE pulse for the last
sector erase command pulse and terminates when the data on DQ7 is “1” (See Write Operation Status section.)
at which time the devices return to the read mode. Data polling must be performed at an address within any of
the sectors being erased. Multiple Sector Erase Time; [Sector Erase Time + Sector Program Time
(Preprogramming)] × Number of Sector Erase
Figure 21 illustrates the Embedded EraseTM Algorithm using typical command strings and bus operations.
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