MBM29F080A datasheet(15/44 Pages) SPANSION

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MBM29F080A-55/-70/-90

This automatic programming operation is completed when the data on DQ7 is equivalent to data written to this

bit at which time the device returns to the read mode and addresses are no longer latched. (See “Hardware

Sequence Flags Table” in “sFLEXIBLE SECTOR-ERASE ARCHITECTURE”.) Therefore, the device requires

that a valid address to the device be supplied by the system at this particular instance of time. 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 a 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 reset/read mode will show that the data is still “0”. Only

erase operations can convert “0”s to “1”s.

“Embedded ProgramTM Algorithm” in “sFLOW CHART” illustrates the Embedded ProgrammingTM Algorithm

using typical command strings and bus operations.

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 device will automatically program and verify the entire memory for an all zero

data pattern prior to electrical erase. 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.

“Embedded EraseTM Algorithm” in “sFLOW CHART” illustrates the Embedded Erase™ 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 “MBM29F080A Command

Definitions Table” in “sFLEXIBLE SECTOR-ERASE ARCHITECTURE”. 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 device to the read mode, ignoring the previous command string. Resetting

the device once execution has begun will corrupt the data in that sector. In that case, restart the erase on those

sectors and allow them to complete. (Refer to the Write Operation Status section for DQ3, Sector Erase Timer

operation.) Loading the sector erase buffer may be done in any sequence and with any number of sectors (0 to 15).

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