AMC0XXDFLKA Datasheet, PDF (14/46 Pages) Advanced Micro Devices – 4, 8, 20, or 32 Megabyte 5.0 Volt-only Flash Memory PC Card

Sector erase does not require the user to program the
device prior to erase. The device automatically pro-
grams all memory locations to “0” in the sector(s) to be
erased prior to electrical erase. When erasing a sector
or sectors the remaining unselected sectors are not af-
fected. The system is not required to provide any con-
trols or timings during these operations. A Reset
command after the device has begun execution will
stop the device but the data in the operated sector will
be undefined. In that case, restart the erase on that
sector and allow it to complete.
The automatic sector erase begins after the 50 µs time
out from the rising edge of the WE pulse for the last
sector erase command pulse and terminates when the
data on D7 is “1” (see Write Operation Status section)
at which time the device returns to read mode. Data
Polling must be performed at an address within any of
the sectors being erased.
Figure 1 illustrates the Embedded Erase Algorithm
using typical command strings and bus operations.
Start
Write Embedded Erase
Command Sequence
(Table 3 and 4)
Data Poll from Device
(Figure 3)
Erasure Complete
19521D-2
Figure 1. Embedded Erase Algorithm
Embedded Program Algorithm
The Embedded Program setup is a four bus cycle op-
eration that stages the addressed memory sector or
memory segment for automatic programming.
Once the Embedded Program setup operation is per-
formed, the next WE pulse causes a transition to an ac-
tive programming operation. Addresses are internally
latched on the falling edge of the WE pulse. Data is in-
ternally latched on the rising edge of the WE pulse. The
rising edge of WE also begins the programming opera-
tion. The system is not required to provide further con-
trol or timing. The device will automatically provide an
adequate internally generated write pulse and verify
margin. The automatic programming operation is com-
pleted when the data on D7 of the addressed memory
sector or memory segment is equivalent to data written
to this bit (see Write Operation Status section) at which
time the device returns to the Read mode (no write ver-
ify command is required).
Addresses are latched on the falling edge of WE during
the Embedded Program command execution and
hence the system is not required to keep the addresses
stable during the entire Programming operation. How-
ever, once the device completes the Embedded Pro-
gram operation, it returns to the Read mode and
addresses are no longer latched. Therefore, the device
requires that a valid address input to the device is sup-
plied by the system at this particular instant of time.
Otherwise, the system will never read a valid data on
D7. A system designer has two choices to implement
the Embedded Programming algorithm:
1. The system (CPU) keeps the address valid during
the entire Embedded Programming operation, or
2. Once the system executes the Embedded Program-
ming command sequence, the CPU takes away the
address from the device and becomes free to do
other tasks. In this case, the CPU is required to
keep track of the valid address by loading it into a
temporary register. When the CPU comes back for
performing Data Polling, it should reassert the same
address.
However, since the Embedded Programming operation
takes only 8 µs typically, it may be easier for the CPU
to keep the address stable during the entire Embedded
Programming operation instead of reasserting the valid
address during Data Polling. Anyway, this has been left
to the system designer’s choice to go for either opera-
tion. Any commands written to the segment during this
period will be ignored.
Figure 2 and Table 7 illustrate the Embedded Program
Algorithm, a typical command string, and bus operation.
Table 7. Embedded Program Algorithm
Bus Operation
Command
Comments
Standby
Write
Wait for V_CC ramp
Embedded Program
command sequence
3 bus cycle
operation
Write
Program Address/
Data
1 bus cycle
operation
Read
Data Polling to
verify program
Reset Command
The Reset command initializes the sector or segment
to the read mode. Please refer to Tables 3 and 4, “Byte
Command Definitions,” and Table 5, “Word Command
Definitions” for the Reset command operation. The
sector or segment remains enabled for reads until the
command register contents are altered.
14
AmC0XXDFLKA