MBM29LV400TC-55/70/90/MBM29LV400BC-55/70/90
The manufacturer and device codes may also be read via the command register, for instances when the
MBM29LV400TC/BC are erased or programmed in a system without access to high voltage on the A9 pin. The
command sequence is illustrated in “MBM29LV400TC/400BC Standard Command Definitions Table” (■DEVICE
BUS OPERATIONS). (Refer to “2. Autoselect Command” in ■COMMAND DEFINITIONS.)
Byte 0 (A0 = VIL) represents the manufacturer’s code (Fujitsu = 04h) and (A0 = VIH) represents the device identifier
code (MBM29LV400TC = B9h and MBM29LV400BC = BAh for ×8 mode; MBM29LV400TC = 22B9h and
MBM29LV400BC = 22BAh for ×16 mode). These two bytes/words are given in “MBM29LV400TC/400BC Sector
Protection Verify Autoselect Codes Table” and “Extended Autoselect Code Table” (■DEVICE BUS
OPERATIONS). All identifiers for manufactures and device will exhibit odd parity with DQ7 defined as the parity
bit. In order to read the proper device codes when executing the autoselect, A1 must be VIL. (See
“MBM29LV400TC/400BC Sector Protection Verify Autoselect Codes Table” and “Extended Autoselect Code
Table” in ■DEVICE BUS OPERATIONS.)
6. Write
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 VIL, while CE is at VIL and OE is at VIH. Addresses are latched on
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.
7. Sector Protection
The MBM29LV400TC/BC feature hardware sector protection. This feature will disable both program and erase
operations in any number of sectors (0 through 10). 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 VID on address pin A9 and control pin OE, (suggest
VID = 11.5 V), CE = VIL, and A6 = VIL. The sector addresses ( A17, A16, A15, A14, A13, and A12) should be set to the
sector to be protected. “Sector Address Tables (MBM29LV400TC/BC)” in ■FLEXIBLE SECTOR-ERASE
ARCHITECTURE define the sector address for each of the eleven (11) 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 “13. AC Waveforms for Sector Protection
Timing Diagram” in ■TIMING DIAGRAM and “5. Sector Protection Algorithm” in ■FLOW CHART for sector
protection waveforms and algorithm.
To verify programming of the protection circuitry, the programming equipment must force VID on address pin A9
with CE and OE at VIL and WE at VIH. Scanning the sector addresses ( A17, A16, A15, A14, A13, and A12) while (A6,
A1, A0) = (0, 1, 0) will produce a logical “1” code at device output DQ0 for a protected sector. Otherwise the
devices will read 00h for unprotected sector. In this mode, the lower order addresses, except for A0, A1, and A6
are DON’T CARES. Address locations with A1 = VIL are reserved for Autoselect manufacturer and device codes.
A-1 requires to apply to VIL on byte mode.
ItisalsopossibletodetermineifasectorisprotectedinthesystembywritinganAutoselectcommand. Performing
a read operation at the address location XX02h, where the higher order addresses (A17, A16, A15, A14, A13, and
A12) are the desired sector address will produce a logical “1” at DQ0 for a protected sector. See “MBM29LV400TC/
400BC Sector Protection Verify Autoselect Codes Table” and “Extended Autoselect Code Table” in ■DEVICE
BUS OPERATIONS for Autoselect codes.
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