E S I
E S I
ADVANCED INFORMATION
Excel Semiconductor inc.
can only occur after successful completion of spe-
cific command sequences. And several features are
incorporated to prevent inadvertent write cycles
resulting from Vcc power-up and power-down transi-
tion or system noise.
Start
If data=00h, security
RESET# =
VIH or VID
sector is unprotected.
If data=01h, security
sector is protected
Low Vcc Write inhibit
When Vcc is less than V
, the device does not
LKO
Wait 1us
accept any write cycles. This protects data during
Vcc power-up and power-down. The command reg-
ister and all internal program/erase circuits are dis-
abled, and the device resets to the read mode.
Subsequent writes are ignored until Vcc is greater
Remove VIH or VID
from RESET#
Write 60h to
any address
Write reset
command
than V
. The system must provide proper signals
LKO
Write 40h to security
sector address with
A6=0, A1=1,A0=0
to the control pins to prevent unintentional writes
when Vcc is greater than V
.
LKO
Security sector
Protect Verify
complete
Write Pulse “Glitch” Protection
Read from security
sector address with
A6=0,A1=1,A0=0
Noise pulses of less than 5ns (typical) on OE#, CE#
or WE# do not initiate a write cycle.
Logical inhibit
Write cycles are inhibited by holding any one of
Figure 2. Security Sector Protect Verify
Exit from the Security Sector
OE#=V , CE#=V or WE#=V . To initiate a write
IL
IH
IH
cycle, CE# and WE# must be a logical zero while
OE# is a logical one.
Power-up Write Inhibit
Once the Security Sector is locked protected and
verified, the system must write the Exit Security
Sector Region command sequence to return to
reading and writing the remainder of the array.
If WE#=CE#=V and OE#=V during power up, the
IL
IH
device does not accept any commands on the rising
edge of WE#. The internal state machine is automat-
ically reset to the read mode on power-up.
Caution for the Security Sector Protection
The security sector protection must be used with
caution since, once protected, there is no proce-
dure available for unprotecting the security sector
area and none of the bits in the security sector
memory space can be modified in any way.
HARDWARE DATA PROTECTION
The ES29DL320 device provides some protection
measures against accidental erasure or program-
ming caused by spurious system level signals that
may exist during power transition. During power-
up, all internal registers and latches in the device
are cleared and the device automatically resets to
the read mode. In addition, with its internal state
machine built-in the device, any alteration of the
memory contents or any initiation of new operation
11
Rev. 0E May 25, 2006
ES29DL320
EXCELSEMI [ EXCEL SEMICONDUCTOR INC. ]
