MBM29SL800BD Fujitsu Media Devices, MBM29SL800BD Datasheet - Page 17

• Manufacturer Part Number: MBM29SL800BD
• Description: (MBM29SL800TD/BD) FLASH MEMORY CMOS 8 M (1 M X 8/512 K X 16) BIT
• Manufacturer: Fujitsu Media Devices

Chip Erase
Sector Erase
system at this particular instance of time. Hence, Data Polling must be performed at the memory location which
is being programmed.
If hardware reset occurs during the programming operation, it is impossible to guarantee the data are being
written.
Programming is allowed in any sequence and across sector boundaries. Beware that a data “0” cannot be
programmed back to a “1”. Attempting to do so may either hang up the device or result in an apparent success
according to the data polling algorithm but a read from read/reset mode will show that the data is still “0”. Only
erase operations can convert “0”s to “1”s.
“(1) Embedded Program
typical command strings and bus operations.
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 DQ
mode.
Chip Erase Time; Sector Erase Time
“(2) Embedded Erase
command strings and bus operations.
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
erase command, the sector erase operation will begin.
Multiple sectors may be erased concurrently by writing the six bus cycle operations on “MBM29SL800TD/800BD
Standard Command Definitions Table” in
of the Sector Erase command to addresses in other sectors desired to be concurrently erased. The time between
writes must be less than 50 s otherwise that command will not be accepted and erasure will start. It is recom-
mended 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 s 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 s time-out window the timer is reset. (Monitor DQ
open, see section DQ
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 18) .
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 s time out from the rising edge of the WE pulse for the last
sector erase command pulse and terminates when the data on DQ
at which time the devices return to the read mode. Data polling must be performed at an address within any of
30h) is latched on the rising edge of WE. After time-out of 50 s from the rising edge of the last sector
MBM29SL800TD
7
TM
3
is “1” (See Write Operation Status section.) at which time the device returns to read the
, Sector Erase Timer.) Resetting the devices once execution has begun will corrupt the
Algorithm” in FLOW CHART illustrates the Embedded Erase
TM
Algorithm” in FLOW CHART illustrates the Embedded Program
All sectors
DEVICE BUS OPERATION. This sequence is followed with writes
Chip Program Time (Preprogramming)
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to determine if the sector erase timer window is still
/MBM29SL800BD
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is “1” (See Write Operation Status section.)
TM
Algorithm using typical
TM
Algorithm using
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