MBM29LV002TC Fujitsu Microelectronics, Inc., MBM29LV002TC Datasheet - Page 13

• Manufacturer Part Number: MBM29LV002TC
• Description: 2m 256k X 8 Bit
• Manufacturer: Fujitsu Microelectronics, Inc.

Write
Sector Protection
Temporary Sector Unprotection
Device erasure and programming are accomplished via the command register. The contents of the register serve
as inputs to the internal state machine. The state machine outputs dictate the function of the device.
The command register itself does not occupy any addressable memory location. The register is a latch used to
store the commands, along with the address and data information needed to execute the command. The
command register is written by bringing WE to V
the falling edge of WE or CE, whichever happens later; while data is latched on the rising edge of WE or CE,
whichever happens first. Standard microprocessor write timings are used.
Refer to AC Write Characteristics and the Erase/Programming Waveforms for specific timing parameters.
The MBM29LV002TC/BC feature hardware sector protection. This feature will disable both program and erase
operations in any number of sectors (0 through 6). The sector protection feature is enabled using programming
equipment at the user’s site. The devices are shipped with all sectors unprotected. Alternatively, Fujitsu may
program and protect sectors in the factory prior to shiping the device.
To activate this mode, the programming equipment must force V
V
to be protected. Tables 4 and 5 define the sector address for each of the seven (7) individual sectors. Programming
of the protection circuitry begins on the falling edge of the WE pulse and is terminated with the rising edge of
the same. Sector addresses must be held constant during the WE pulse. See Figures 13 and 21 for sector
protection waveforms and algorithm.
To verify programming of the protection circuitry, the programming equipment must force V
with CE and OE at V
A
devices will read 00H for unprotected sector. In this mode, the lower order addresses, except for A
A
codes.
It is also possible to determine if a sector is protected in the system by writing an Autoselect command. Performing
a read operation at the address location XX02H, where the higher order addresses (A
are the desired sector address will produce a logical “1” at DQ
for Autoselect codes.
This feature allows temporary unprotection of previously protected sectors of the MBM29LV002TC/BC devices
in order to change data. The Sector Unprotection mode is activated by setting the RESET pin to high voltage
(12 V). During this mode, formerly protected sectors can be programmed or erased by selecting the sector
addresses. Once the 12 V is taken away from the RESET pin, all the previously protected sectors will be protected
again. See Figures 14 and 22.
ID
1
10
, A
= 11.5 V), CE = V
are DON’T CARES. Address locations with A
0
) = (0, 0, 1, 0) will produce a logical “1” code at device output DQ
MBM29LV002TC
IL
IL
, and A
and WE at V
6
= V
IL
. The sector addresses (A
IH
. Scanning the sector addresses (A
-70/-90/-12
IL
, while CE is at V
1
= V
IL
are reserved for Autoselect manufacturer and device
17
/MBM29LV002BC
, A
ID
0
for a protected sector. See Tables 3.1 and 3.2
on address pin A
16
, A
IL
and OE is at V
15
, A
0
17
for a protected sector. Otherwise the
14
, A
, and A
16
, A
15
9
13
IH
and control pin OE, (suggest
, A
) should be set to the sector
. Addresses are latched on
14
17
, and A
, A
16
ID
, A
on address pin A
13
15
) while (A
, A
0
-70/-90/-12
, A
14
, and A
1
, A
10
6
, and
, A
13
6
9
)
,
13