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.
START
Sector protection/unprotection must be implemented using
programming equipment. The procedure requires a high
voltage (VID) 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.
RESET = VID
(Note 1)
Hardware Data Protection
Perform Erase or
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 VCC power-up transitions, or from system
noise. The device is powered up to read array data to
avoid accidentally writing data to the array.
Program Operations
RESET = VIH
Write Pulse "Glitch" Protection
Noise pulses of less than 5ns (typical) on
,
or
OE CE
Temporary Sector
Unprotect
do not initiate a write cycle.
WE
Completed (Note 2)
Logical Inhibit
Write cycles are inhibited by holding any one of
=VIL,
OE
CE
= VIH or
= VIH. To initiate a write cycle,
and
WE
CE
Notes:
must be a logical zero while
is a logical one.
WE
OE
1. All protected sectors unprotected.
2. All previously protected sectors are protected once again.
Power-Up Write Inhibit
If
=
= VIL and
= VIH during power up, the
OE
WE
device does not accept commands on the rising edge of
. The internal state machine is automatically reset to
CE
Figure 1. Temporary Sector Unprotect Operation
WE
reading array data on the initial power-up.
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
pin to
RESET
VID. During this mode, formerly protected sectors can be
programmed or erased by selecting the sector addresses.
Once VID is removed from the
pin, all the
RESET
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 ]
