A29001/A290011 Series
Sector Protection/Unprotection
The hardware sector protection feature disables both
program and erase operations in any sector. The
hardware sector unprotection feature re-enables both
program and erase operations in previously protected
sectors.
Sector protection/unprotection must be implemented using
programming equipment. The procedure requires a high
voltage (V
ID
) on address pin A9 and the control pins.
The device is shipped with all sectors unprotected.
It is possible to determine whether a sector is protected or
unprotected. See "Autoselect Mode" for details.
START
RESET = V
ID
(Note 1)
Hardware Data Protection
The requirement of command unlocking sequence for
programming or erasing provides data protection against
inadvertent writes (refer to the Command Definitions
table). 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
CC
power-up transitions, or from system
noise. The device is powered up to read array data to
avoid accidentally writing data to the array.
Perform Erase or
Program Operations
RESET = V
IH
Write Pulse "Glitch" Protection
Noise pulses of less than 5ns (typical) on
OE
,
CE
or
WE
do not initiate a write cycle.
Temporary Sector
Unprotect
Completed (Note 2)
Logical Inhibit
Write cycles are inhibited by holding any one of
OE
=V
IL
,
CE
= V
IH
or
WE
= V
IH
. To initiate a write cycle,
CE
and
WE
must be a logical zero while
OE
is a logical one.
Power-Up Write Inhibit
If
WE
=
CE
= V
IL
and
OE
= V
IH
during power up, the
device does not accept commands on the rising edge of
WE
. The internal state machine is automatically reset to
reading array data on the initial power-up.
Notes:
1. All protected sectors unprotected.
2. All previously protected sectors are protected once again.
Figure 1. Temporary Sector Unprotect Operation
Temporary Sector Unprotect (N/A A290011)
This feature allows temporary unprotection of previous
protected sectors to change data in-system. The Sector
Unprotect mode is activated by setting the
RESET
pin to
V
ID
. During this mode, formerly protected sectors can be
programmed or erased by selecting the sector addresses.
Once V
ID
is removed from the
RESET
pin, all the
previously protected sectors are protected again. Figure 1
shows the algorithm, and the Temporary Sector Unprotect
diagram shows the timing waveforms, for this feature.
(December, 2004, Version 1.3)
7
AMIC Technology, Corp.
AMICC [ AMIC TECHNOLOGY ]
