MBM29LV080A Fujitsu Media Devices, MBM29LV080A Datasheet - Page 11

• Manufacturer Part Number: MBM29LV080A
• Description: 8M (1M x 8) BIT
• Manufacturer: Fujitsu Media Devices

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 com-
mand register is written by bringing WE to V
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 MBM29LV080A features hardware sector protection. This feature will disable both program and erase
operations in any number of sectors (0 through 15). The sector protection feature is enabled using programming
equipment at the user’s site. The device is shipped with all sectors unprotected.
To activate this mode, the programming equipment must force V
V
the sector to be protected. Tables 4 and 5 define the sector address for each of the sixteen (16) 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
will read 00H for unprotected sector. In this mode, the lower order addresses, except for A
DON’T CARES. Address locations with A
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
the sector address will produce a logical “1” at DQ
codes.
This feature allows temporary unprotection of previously protected sectors of the MBM29LV080A device 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 figure 15 and 22.
ID
0
) = (0, 0, 1, 0) will produce a logical “1” code at device output DQ
= 11.5 V), CE = V
IL
IL
, A
and WE at V
0
= A
6
= V
IL
, and A
IH
. Scanning the sector addresses (A
1
= V
1
IL
= V
, while CE is at V
IL
IH
are reserved for Autoselect manufacturer and device codes.
. The sector addresses (A
0
for a protected sector. See Tables 3.1 and 3.2 for Autoselect
IL
ID
MBM29LV080A
and OE is at V
on address pin A
0
for a protected sector. Otherwise the devices
19
, A
19
, A
18
IH
, A
18
. Addresses are latched on the
, A
9
17
and control pin OE, (suggest
,and A
17
,and A
19
, A
16
0
ID
, A
18
) while (A
16
on address pin A
, A
) should be set to
1
, A
17
6
,and A
-70/-90/-12
, and A
10
, A
16
10
). are
6
, A
are
1
9
,
11