AM29PDL640AGA85NS SPANSION [SPANSION], AM29PDL640AGA85NS Datasheet - Page 24

• Manufacturer Part Number: AM29PDL640AGA85NS
• Description: 64 Megabit (4 M x 16-Bit) CMOS 3.0 Volt-only, Simultaneous Operation Flash Memory and 16 Mbit (1 M x 16-Bit) Pseudo Static RAM
• Manufacturer: SPANSION [SPANSION]

number of times, but can be programmed and locked
only once. Note that the accelerated programming
(ACC) and unlock bypass functions are not available
when programming the SecSi Sector.
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.
22
Write the three-cycle Enter SecSi Sector Region
command sequence, and then follow the in-system
sector protect algorithm as shown in Figure Note:,
except that RESET# may be at either V
This allows in-system protection of the SecSi Sector
Region without raising any device pin to a high volt-
age. Note that this method is only applicable to the
SecSi Sector.
To verify the protect/unprotect status of the SecSi
Sector, follow the algorithm shown in Figure 3.
P R E L I M I N A R Y
IH
or V
Am49PDL640AG
ID
.
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.
Figure 3. SecSi Sector Protect Verify
Write 40h to SecSi
Read from SecSi
Sector address
Sector address
A1 = 1, A0 = 0
A1 = 1, A0 = 0
Write 60h to
with A6 = 0,
any address
with A6 = 0,
RESET# =
V
Wait 1 µs
START
IH
or V
ID
Remove V
SecSi Sector is
SecSi Sector is
If data = 00h,
If data = 01h,
from RESET#
Protect Verify
SecSi Sector
unprotected.
Write reset
protected.
command
complete
November 20, 2003
IH
or V
ID