AM29PDL128G70 SPANSION [SPANSION], AM29PDL128G70 Datasheet - Page 30

• Manufacturer Part Number: AM29PDL128G70
• Description: 128 Megabit (8 M x 16-Bit/4 M x 32-Bit) CMOS 3.0 Volt-only, Simultaneous Read/ Write Flash Memory with VersatileIO Control
• Manufacturer: SPANSION [SPANSION]

The SecSi Sector area can be protected using one of
the following procedures:
Once the SecSi Sector is locked and verified, the sys-
tem must write the Exit SecSi Sector Region com-
mand sequence to return to reading and writing the
remainder of the array.
The SecSi Sector lock must be used with caution
since, once locked, there is no procedure available for
unlocking the SecSi Sector area and none of the bits
in the SecSi Sector memory space can be modified in
any way.
SecSi Sector Protection Bit
The SecSi Sector Protection Bit prevents program-
ming of the SecSi Sector memory area. Once set, the
SecSi Sector memory area contents are non-modifi-
able.
Utilizing Password and SecSi Sector Concurrently
The password must be stored in the first eight bytes of
the SecSi Sector. Once the device is permanently
locked into the Password Protection Mode, the erase,
program, and read operation no longer work on those
eight bytes of password in the SecSi Sector. Once the
SecSi Sector protection bit is programmed, no location
in the SecSi Sector may be programmed. To use both
Password Protection and the SecSi Sector concur-
rently, the user must always program the password
into the first eight bytes of the SecSi Sector before ei-
ther the Password Protection Mode is selected or the
SecSi Sector protection bit is programmed.
Method 1
1. Enter the SecSi Sector by issuing the SecSi Sector
2. Program the 64-bit password by issuing the Pass-
3. Lock the password by issuing the Password Protec-
4. Program the SecSi Sector, excluding bytes 0–7.
5. Lock the SecSi Sector by issuing the SecSi Sector
July 29, 2002
Write the three-cycle Enter SecSi Sector Region
command sequence, and then follow the in-system
sector protect algorithm as shown in
cept that RESET# may be at either V
allows in-system protection of the SecSi Sector Re-
gion without raising any device pin to a high voltage.
Note that this method is only applicable to the SecSi
Sector.
Write the three-cycle Enter SecSi Sector Secure
Region command sequence, and then use the alter-
nate method of sector protection described in the
Sector Protection
Entry command.
word Program and Password Verify commands
tion Mode Locking Bit Program command.
Protection Bit Program command.
section.
IH
Figure
P R E L I M I N A R Y
or V
ID
1, ex-
. This
Am29PDL128G
6. Exit the SecSi Sector by issuing the SecSi Sector
Note: Step 4 may be performed prior to step 2.
Method 2
1. Enter the SecSi Sector by issuing the SecSi Sector
2. Program the entire SecSi Sector, including the first
3. Lock the password by issuing the Password Protec-
4. Lock the SecSi Sector by issuing the SecSi Sector
5. Exit the SecSi Sector by issuing the SecSi Sector
Note: Step 4 may be performed prior to step 3.
Hardware Data Protection
The command sequence requirement of unlock cycles
for programming or erasing provides data protection
against inadvertent writes. In addition, the following
hardware data protection measures prevent accidental
erasure or programming, which might otherwise be
caused by spurious system level signals during V
power-up and power-down transitions, or from system
noise.
Low V
When V
cept any write cycles. This protects data during V
power-up and power-down. The command register
and all internal program/erase circuits are disabled,
and the device resets to the read mode. Subsequent
writes are ignored until V
system must provide the proper signals to the control
pins to prevent unintentional writes when V
greater than V
Write Pulse “Glitch” Protection
Noise pulses of less than 5 ns (typical) on OE#, CE#
or WE# do not initiate a write cycle.
Logical Inhibit
Write cycles are inhibited by holding any one of OE# =
V
CE# and WE# must be a logical zero while OE# is a
logical one.
Power-Up Write Inhibit
If WE# = CE# = V
the device does not accept commands on the rising
edge of WE#. The internal state machine is automati-
cally reset to the read mode on power-up.
IL
, CE# = V
Exit or Reset command
Entry command.
eight bytes contain the 64-bit password.
tion Mode Locking Bit Program command.
Protection Bit Program command.
Exit or Reset command
CC
CC
Write Inhibit
is less than V
IH
LKO
or WE# = V
.
IL
and OE# = V
LKO
CC
IH
, the device does not ac-
is greater than V
. To initiate a write cycle,
IH
during power up,
LKO
. The
CC
29
CC
CC
is