FLASH MEMORY PROGRAM/ERASE
OPERATIONS
has been achieved for the memory array (no erase ver-
ify command is required). The margin voltages are in-
ternally generated in the same manner as when the
standard erase verify command is used.
Embedded Erase Algorithm
The automatic chip erase does not require the device
to be entirely pre-programmed prior to executing the
Embedded set-up erase command and Embedded
erase command. Upon executing the Embedded erase
command the device automatically will program and
verify the entire memory for an all zero data pattern.
The system is not required to provide any controls or
timing during these operations.
The Embedded Erase Set-Up command is a command
only operation that stages the device for automatic
electrical erasure of all bytes in the array. Embedded
Erase Setup is performed by writing 30h to the com-
mand register.
When the device is automatically verified to contain an
all zero pattern, a self-timed chip erase and verify be-
gin. The erase and verify operation are complete when
the data on DQ7 is “1" (see Write Operation Status sec-
tion) atwhich time the device returns to Read mode.
The system is not required to provide any control or
timing during these operations.
To commence automatic chip erase, the command 30h
must be written again to the command register. The au-
tomatic erase begins on the rising edge of the WE and
terminates when the data on DQ7 is “1" (see Write Op-
eration Status section) at which time the device returns
to Read mode.
Figure 1 and Table 4 illustrate the Embedded Erase al-
gorithm, a typical command string and bus operation.
When using the Embedded Erase algorithm, the erase
automatically terminates when adequate erase margin
START
Apply V
PPH
Write Embedded Erase Setup Command
Write Embedded Erase Command
Data# Poll from Device
Erasure Completed
18879C-6
Figure 1. Embedded Erase Algorithm
Table 4. Embedded Erase Algorithm
Command
Bus Operations
Standby
Comments
(see Note)
PPH
Wait for V Ramp to V
PP
Embedded Erase Setup Command Data = 30h
Embedded Erase Command Data = 30h
Write
Read
Data# Polling to Verify Erasure
Compare Output to FFh
Standby
Read
Available for Read Operations
Note: See AC and DC Characteristics for values of V parameters. The V power supply can be hard-wired to the device or
PP
PP
switchable. When V is switched, V
may be ground, no connect with a resistor tied to ground, or less than V + 2.0 V. Refer
PP
PPL
CC
to Functional Description.
12
Am28F256A
SPANSION [ SPANSION ]
