MBM29LV008TA/BA-70/90
The manufacturer and device codes may also be read via the command register, for instances when the
MBM29LV008TA/BA are erased or programmed in a system without access to high voltage on the A9 pin. The
command sequence is illustrated in âMBM29LV008TA/008BA Standard Command Definitionsâ in s DEVICE
BUS OPERATION. (Refer to âAutoselect Commandâ.)
Byte 0 (A0 = VIL) represents the manufacturerâs code (Fujitsu = 04h) and (A0 = VIH) represents the device identifier
code (MBM29LV008TA = 3Eh and MBM29LV008BA = 37h). These two bytes/words are given in
âMBM29LV008TA/008BA Sector Protection Verify Autoselect Codesâ and âExpanded Autoselect Code Tableâ in
s DEVICE BUS OPERATION. 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
âMBM29LV008TA/008BA Sector Protection Verify Autoselect Codesâ and âExpanded Autoselect Code Tableâ in
s DEVICE BUS OPERATION.)
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 âAC Waveforms for Alternate WE Controlled Program Operationsâ and âAC Waveforms for Alternate CE
Controlled Program Operationsâ in s TIMING DIAGRAM.
Sector Protection
The MBM29LV008TA/BA feature hardware sector protection. This feature will disable both program and erase
operations in any number of sectors (0 through 18). The sector protection feature is enabled using programming
equipment at the userâs 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 (A19, A18, A17, A16, A15, A14, and A13) should be set to
the sector to be protected. âSector Address Tables (MBM29LV008TA) â and âSector Address Tables
(MBM29LV008BA) â in s FLEXIBLE SECTOR-ERASE ARCHITECTURE define the sector address for each of
the nineteen (19) 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 â (10) AC Waveforms for Sector Protection Timing Diagramâ in s TIMING DIAGRAM and â
(5) Sector Protection Algorithmâ in s 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 (A19, A18, A17, A16, A15, A14, and A13) while
(A10, A6, A1, A0) = (0, 0, 1, 0) will produce a logical â1â 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, A6,
and A10 are DONâT CARES. Address locations with A1 = VIL are reserved for Autoselect manufacturer and device
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 (A19, A18, A17, A16, A15, A14,
and A13) are the desired sector address will produce a logical â1â at DQ0 for a protected sector. See
âMBM29LV008TA/008BA Sector Protection Verify Autoselect Codesâ and âExpanded Autoselect Code Tableâ
in s DEVICE BUS OPERATION for Autoselect codes.
14