256Mb and 512Mb (256Mb/256Mb), P30-65nm
Erase Operations
Erase Operations
Flash erasing is performed on a block basis. An entire block is erased each time an erase
command sequence is issued, and only one block is erased at a time. When a block is
erased, all bits within that block read as logical ones. The following sections describe
block erase operations in detail.
Block Erase
Block erase operations are initiated by writing the Block Erase Setup command to the
address of the block to be erased. Next, the Block Erase Confirm command is written to
the address of the block to be erased. If the device is placed in standby (CE# deasserted)
during an erase operation, the device completes the erase operation before entering
standby. The VPP value must be above VPPLK and the block must be unlocked.
During a block erase, the Write State Machine (WSM) executes a sequence of internally-
timed events that conditions, erases, and verifies all bits within the block. Erasing the
flash memory array changes “zeros” to “ones”. Memory block array that are ones can be
changed to zeros only by programming the block.
The Status Register can be examined for block erase progress and errors by reading any
address. The device remains in the Read Status Register state until another command is
written. SR.0 indicates whether the addressed block is erasing. Status Register bit SR.7 is
set upon erase completion.
Status Register bit SR.7 indicates block erase status while the sequence executes. When
the erase operation has finished, Status Register bit SR.5 indicates an erase failure if set.
SR.3 set would indicate that the WSM could not perform the erase operation because
VPP was outside of its acceptable limits. SR.1 set indicates that the erase operation at-
tempted to erase a locked block, causing the operation to abort.
Before issuing a new command, the Status Register contents should be examined and
then cleared using the Clear Status Register command. Any valid command can follow
once the block erase operation has completed.
The Block Erase operation is aborted by performing a reset or powering down the de-
vice. In this case, data integrity cannot be ensured, and it is recommended to erase
again the blocks aborted.
Blank Check
The Blank Check operation determines whether a specified main block is blank; that is,
completely erased. Without Blank Check, Block Erase would be the only other way to
ensure a block is completely erased. Blank Check is especially useful in the case of erase
operation interrupted by a power loss event.
Blank check can apply to only one block at a time, and no operations other than Status
Register Reads are allowed during Blank Check (e.g. reading array data, program, erase
etc). Suspend and resume operations are not supported during Blank Check, nor is
Blank Check supported during any suspended operations.
Blank Check operations are initiated by writing the Blank Check Setup command to the
block address. Next, the Check Confirm command is issued along with the same block
address. When a successful command sequence is entered, the device automatically en-
ters the Read Status State. The WSM then reads the entire specified block, and deter-
mines whether any bit in the block is programmed or over-erased.
PDF: 09005aef84566799
p30_65nm_256Mb-512mb.pdf - Rev. A 1/13 EN
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