MBM29F017A Datasheet, PDF (15/49 Pages) SPANSION – FLASH MEMORY CMOS 16M (2M x 8) BIT

MBM29F017A-70/-90/-12
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 com-
mand 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.
Sector Group Protection
The MBM29F017A features hardware sector group protection. This feature will disable both program and erase
operations in any combination of eight sector groups of memory. Each sector group consists of four adjacent
sectors grouped in the following pattern: sectors 0-3, 4-7, 8-11, 12-15, 16-19, 20-23, 24-27, and 28-31 (see
“Sector Group Addresses” in sFLEXIBLE SECTOR-ERASE ARCHITECTURE). The sector group protection
feature is enabled using programming equipment at the user's site. The device is shipped with all sector groups
unprotected.
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. The sector addresses (A20, A19, and A18) should be set to the sector to be protected.
“Sector Address Table” and “Sector Group Addresses” in sFLEXIBLE SECTOR-ERASE ARCHITECTURE
define the sector address for each of the thirty two (32) individual sectors, and the sector group address for each
of the eight (8) individual group 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. Refer to figures 14 and 21 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 (A20, A19, and A18) while (A6, A1, A0) = (0,
1, 0) will produce a logical “1” code at device output DQ0 for a protected sector. Otherwise the device will produce
00h for unprotected sector. In this mode, the lower order addresses, except for A0, A1, and A6 are don’t care.
Address locations with A1 = VIL are reserved for Autoselect manufacturer and device codes.
It is also possible to determine if a sector group is protected in the system by writing an Autoselect command.
Performing a read operation at the address location XX02h, where the higher order addresses (A20, A19, and
A18) are the desired sector group address will produce a logical “1” at DQ0 for a protected sector group. See
“MBM29F017A Sector Protection Verify Autoselect Codes” in sDEVICE BUS OPERATION for Autoselect codes.
Temporary Sector Group Unprotection
This feature allows temporary unprotection of previously protected sector groups of the MBM29F017A device
in order to change data. The Sector Group Unprotection mode is activated by setting the RESET pin to high
voltage (12 V). During this mode, formerly protected sector groups can be programmed or erased by selecting
the sector group addresses. Once the 12 V is taken away from the RESET pin, all the previously protected sector
groups will be protected again. Refer to “AC Waveforms for Sector Group Protection” in sTIMING DIAGRAM
and “Sector Group Protection Algorithm” in sFLOW CHART.
Command Definitions
Device operations are selected by writing specific address and data sequences into the command register.
Writing incorrect address and data values or writing them in the improper sequence will reset the device to the
read mode. “MBM29F017A Command Definitions” in sDEVICE BUS OPERATION defines the valid register
command sequences. Note that the Erase Suspend (B0h) and Erase Resume (30h) commands are valid only
while the Sector Erase operation is in progress. Moreover, both Read/Reset commands are functionally equiv-
alent, resetting the device to the read mode.
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