MBM29LV400TC-55PF Meet Spansion Inc., MBM29LV400TC-55PF Datasheet - Page 19

• Manufacturer Part Number: MBM29LV400TC-55PF
• Description: Flash Memory Cmos 4m 512k ? 8/256k ? 16 Bit
• Manufacturer: Meet Spansion Inc.

18
MBM29LV400TC
4. Chip Erase
5. Sector Erase
The automatic programming operation is completed when the data on DQ
bit at which time the devices return to the read mode and addresses are no longer latched. (See “Hardware
Sequence Flags Table” in COMMAND DEFINITIONS.) Therefore, the devices require that a valid address to
the devices be supplied by the system at this particular instance of time. Hence, Data Polling must be performed
at the memory location which is being programmed.
Any commands written to the chip during this period will be ignored. 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
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=30h) is latched on the rising edge of WE. After time-out of 50 s 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 “MBM29LV400TC/400BC
Standard Command Definitions Table” ( DEVICE BUS OPERATIONS). 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 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
is still open, see section DQ
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 “8. Write Operation Status” 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).
TM
7
is “1” (See “8. Write Operation Status”.) at which time the device returns to read the mode.
Algorithm” in FLOW CHART illustrates the Embedded Erase
TM
Algorithm” in FLOW CHART illustrates the Embedded Program
3
, Sector Erase Timer.) Any command other than Sector Erase or Erase Suspend
-55/70/90
All sectors + Chip Program Time (Preprogramming)
/MBM29LV400BC
3
to determine if the sector erase timer window
7
is equivalent to data written to this
-55/70/90
TM
Algorithm using typical
TM
Algorithm using