MBM29DL16XTE/BE70/90
group. See “MBM29DL16XTE/BE Sector Group Protection Verify Autoselect Codes Tables” and “Expanded
Autoselect Code Tables” in ■DEVICE BUS OPERATION for Autoselect codes.
• Temporary Sector Group Unprotection
This feature allows temporary unprotection of previously protected sector groups of the MBM29DL16XTE/BE
devices in order to change data. The Sector Group Unprotection mode is activated by setting the RESET pin to
high voltage (VID). During this mode, formerly protected sector groups can be programmed or erased by selecting
the sector group addresses. Once the VID is taken away from the RESET pin, all the previously protected sector
groupswillbeprotectedagain. Referto“(16)TemporarySectorGroupUnprotectionTimingDiagram”in ■TIMING
DIAGRAM and “(6) Temporary Sector Group Protection Algorithm” in ■FLOW CHART.
• RESET
Hardware Reset
The MBM29DL16XTE/BE devices may be reset by driving the RESET pin to VIL. The RESET pin has a pulse
requirement and has to be kept low (VIL) for at least “tRP” in order to properly reset the internal state machine.
Any operation in the process of being executed will be terminated and the internal state machine will be reset
to the read mode “tREADY” after the RESET pin is driven low. Furthermore, once the RESET pin goes high, the
devices require an additional “tRH” before it will allow read access. When the RESET pin is low, the devices will
be in the standby mode for the duration of the pulse and all the data output pins will be tri-stated. If a hardware
reset occurs during a program or erase operation, the data at that particular location will be corrupted. Please
note that the RY/BY output signal should be ignored during the RESET pulse. See “(11) RESET, RY/BY Timing
Diagram” in ■TIMING DIAGRAM for the timing diagram. Refer to Temporary Sector Group Unprotection for
additional functionality.
• Byte/Word Configuration
The BYTE pin selects the byte (8-bit) mode or word (16-bit) mode for the MBM29DL16XTE/BE devices. When
this pin is driven high, the devices operate in the word (16-bit) mode.The data is read and programmed at DQ15
to DQ0. When this pin is driven low, the devices operate in byte (8-bit) mode. Under this mode, the DQ15/A-1 pin
becomes the lowest address bit and DQ14 to DQ8 bits are tri-stated. Refer to “(12) Timing Diagram for Word
Mode Configuration”, “(13) Timing Diagram for Byte Mode Configuration” and “(14) BYTE Timing Diagram for
Write Operations” in ■TIMING DIAGRAM.
• Boot Block Sector Protection
The Write Protect function provides a hardware method of protecting certain boot sectors without using VID. This
function is one of two provided by the WP/ACC pin.
If the system asserts VIL on the WP/ACC pin, the device disables program and erase functions in the two
“outermost” 8K byte boot sectors (MBM29DL16XTE: SA37 and SA38, MBM29DL16XBE: SA0 and SA1)
independently of whether those sectors were protected or unprotected using the method described in “Sector
Group Protection”. The two outermost 8K byte boot sectors are the two sectors containing the lowest addresses
inabottom-boot-configureddevice, orthetwosectorscontainingthehighestaddressesinatop-boot-congfigured
device.
If the system asserts VIH on the WP/ACC pin, the device reverts to whether the two outermost 8K byte boot
sectors were last set to be protected or unprotected. That is, sector group protection or unprotection for these
two sectors depends on whether they were last protected or unprotected using the method described in “Sector
Group Protection”.
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