MBM29QM12DH Fujitsu Microelectronics, Inc., MBM29QM12DH Datasheet - Page 28

• Manufacturer Part Number: MBM29QM12DH
• Description: Page Mode Flash Memory 128m 8m X 16 Bit
• Manufacturer: Fujitsu Microelectronics, Inc.

RESET
Hardware Reset
Boot Block Sector Protection
HiddenROM Region
for program operation will reduce to about 60%. This function is primarily intended to allow high speed program,
so caution is needed as the sector group will temporarily be unprotected.
The system would use a fast program command sequence when programming during acceleration mode.
Set command to fast mode and reset command from fast mode are not necessary. When the device enters the
acceleration mode, the device automatically set to fast mode. Therefore, the pressent sequence could be used
for programming and detection of completion during acceleration mode.
Removing V
ACC pin while programming. See “Accelerated Program Timing Diagram” in “ TIMING DIAGRAM”.
The device may be reset by driving the RESET pin to V
be kept low (V
of being executed will be terminated and the internal state machine will be reset to the read mode “t
the RESET pin is driven low. Furthermore, once the RESET pin goes high the device requires an additional “t
before it will allow read access. When the RESET pin is low, the device 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 “RESET, RY/BY Timing Diagram” in “ TIMING DIAGRAM” for
the timing diagram. Refer to Temporary Sector Group Unprotection for additional functionality.
The write protection function provides a hardware method of protecting certain boot sectors without using V
This function is one of two provided by the WP/ACC pin.
If the system asserts V
outermost 8K bytes on both ends of boot sectors (SA0, SA1, SA268, SA269) independently of whether those
sectors are protected or unprotected using the method described in “Sector Group Protection”.
If the system asserts V
ends of boot sectors ware last set to be protected or unprotected. Sector group protection or unprotection for
these four sectors depends on whether they ware last protected or unprotected using the method described in
“Sector Group Protection”.
The HiddenROM feature provides a Flash memory region that the system may access through a new command
sequence. This is primarily intended for customers who wish to use an Electronic Serial Number (ESN) in the
device with the ESN protected against modification. Once the HiddenROM region is protected, any further
modification of that region becomes impossible. This ensures the security of the ESN once the product is shipped
to the field. ONLY Program is possible in this area until it is protected. Once it is protected, it is impossible to
unprotect, so please use this with caution.
HiddenROM area is 128 words (64 words for factory and 64 words for customer) in length and is stored at the
same address of the "outermost" 4 Kwords boot sector. The device occupies the address of the 000000h to
00007Fh. After the system has written the Enter HiddenROM command sequence, the system may read the
HiddenROM region by using the addresses normally occupied by the boot sector (particular area of SA0). That
is, the device sends all commands that would normally be sent to the boot sector to the HiddenROM region.
This mode of operation continues until the system issues the Exit HiddenROM command sequence, or until
power is removed from the device. On power-up, or following a hardware reset, the device reverts to sending
commands to the boot sector.
HiddenROM area is devided into two regions, which are Factory Locked area and Customer Locked area. The
Factory Locked area is 64 words (address: 000000h to 00003Fh) that is programmed and locked at Fujitsu. The
Customer Locked area is also 64 words (address: 000040h to 00007Fh) that is programmed and locked at user.
The Factory indicator Bit (DQ
from the factory. The Customer Indicator Bit (DQ
is locked. The Factory Locked area can be programmed and protected at Fujitsu ONLY and is always protected
ACC
IL
) for at least “t
from the WP/ACC pin returns the device to normal operation. Do not remove V
IH
IL
on the WP/ACC pin, the device reverts to whether the two outermost 8K byte on both
on the WP/ACC pin, the device disables program and erase functions in the two
RP
7
) is used to indicate whether or not the Factory Locked area is locked when shipped
” in order to properly reset the internal state machine. Any operation in the process
6
) is used to indicate whether or not the Customer Locked area
IL
. The RESET pin has a pulse requirement and has to
MBM29QM12DH
ACC
READY
from WP/
” after
-60
RH
ID
”
.
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