Unlock Bypass command
The Unlock Bypass command is used in conjunction with the Unlock Bypass Program
command to program the memory faster than with the standard program commands. When
the cycle time to the device is long, considerable time saving can be made by using these
commands. Three Bus Write operations are required to issue the Unlock Bypass command.
Once the Unlock Bypass command has been issued the memory enters Unlock Bypass
mode. The Unlock Bypass Program command can then be issued to program addresses or
the Unlock Bypass Reset command can be issued to return to Read mode. In Unlock
Bypass mode the memory can be read as if in Read mode.
When VPP is applied to the VPP/Write Protect pin the memory automatically enters the
Unlock Bypass mode and the Unlock Bypass Program command can be issued
immediately. Care must be taken because applying a 12V VPP voltage to the VPP/WP pin
will temporarily unprotect any protected block.
Unlock Bypass Program command
The Unlock Bypass Program command can be used to program one address in the memory
array at a time. The command requires two Bus Write operations, the final write operation
latches the address and data, and starts the Program/Erase Controller.
The Program operation using the Unlock Bypass Program command behaves identically to
the Program operation using the Program command. The operation cannot be aborted, a
Bus Read operation outputs the Status register. See the Program command for details on
Unlock Bypass Reset command
The Unlock Bypass Reset command can be used to return to Read/Reset mode from
Unlock Bypass mode. Two Bus Write operations are required to issue the Unlock Bypass
Reset command. Read/Reset command does not exit from Unlock Bypass mode.
Chip Erase command
The Chip Erase command can be used to erase the entire chip. Six Bus Write operations
are required to issue the Chip Erase Command and start the Program/Erase Controller.
If any blocks are protected then these are ignored and all the other blocks are erased. If all
of the blocks are protected the Chip Erase operation appears to start but will terminate
within about 100µs, leaving the data unchanged. No error condition is given when protected
blocks are ignored.
During the erase operation the memory will ignore all commands, including the Erase
Suspend command. It is not possible to issue any command to abort the operation. Typical
chip erase times are given in Table 6. All Bus Read operations during the Chip Erase
operation will output the Status register on the Data Inputs/Outputs. See the section on the
Status register for more details.
After the Chip Erase operation has completed the memory will return to the Read mode,
unless an error has occurred. When an error occurs the memory will continue to output the