M29F400FB55M3F2 Micron Technology Inc, M29F400FB55M3F2 Datasheet - Page 60

• Manufacturer Part Number: M29F400FB55M3F2
• Manufacturer: Micron Technology Inc

Specifications of M29F400FB55M3F2

• Cell Type: NOR
• Density: 4Mb
• Access Time (max): 55ns
• Interface Type: Parallel
• Boot Type: Bottom
• Address Bus: 19/18Bit
• Operating Supply Voltage (typ): 5V
• Operating Temp Range: -40C to 125C
• Package Type: SO W
• Program/erase Volt (typ): 4.5 to 5.5V
• Sync/async: Asynchronous
• Operating Temperature Classification: Automotive
• Operating Supply Voltage (min): 4.5V
• Operating Supply Voltage (max): 5.5V
• Word Size: 8/16Bit
• Number Of Words: 512K/256K
• Supply Current: 20mA
• Mounting: Surface Mount
• Pin Count: 44
• Lead Free Status / Rohs Status: Compliant

Appendix C
C.1
C.2
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Block protection can be used to prevent any operation from modifying the data stored in the
Flash memory. Each Block can be protected individually. Once protected, Program and
Erase operations on the block fail to change the data.
There are three techniques that can be used to control Block Protection, these are the
Programmer technique, the In-System technique and Temporary Unprotection. Temporary
Unprotection is controlled by the Reset/Block Temporary Unprotection pin, RP; this is
described in the Signal Descriptions section.
Unlike the Command Interface of the Program/Erase Controller, the techniques for
protecting and unprotecting blocks could change between different Flash memory suppliers.
Programmer Technique
The Programmer technique uses high (V
cannot be achieved using a standard microprocessor bus, therefore the technique is
recommended only for use in Programming Equipment.
To protect a block follow the flowchart in
Flowchart. During the Block Protect algorithm, the A19-A12 Address Inputs indicate the
address of the block to be protected. The block will be correctly protected only if A19-A12
remain valid and stable, and if Chip Enable is kept Low, V
phases.
The Chip Unprotect algorithm is used to unprotect all the memory blocks at the same time.
This algorithm can only be used if all of the blocks are protected first. To unprotect the chip
follow
Programmer Technique Bus Operations, BYTE = VIH or
operation.
The timing on these flowcharts is critical. Care should be taken to ensure that, where a
pause is specified, it is followed as closely as possible. Do not abort the procedure before
reaching the end. Chip Unprotect can take several seconds and a user message should be
provided to show that the operation is progressing.
In-System Technique
The In-System technique requires a high voltage level on the Reset/Blocks Temporary
Unprotect pin, RP. This can be achieved without violating the maximum ratings of the
components on the microprocessor bus, therefore this technique is suitable for use after the
Flash memory has been fitted to the system.
To protect a block follow the flowchart in
Flowchart. To unprotect the whole chip it is necessary to protect all of the blocks first, then
all the blocks can be unprotected at the same time. To unprotect the chip follow
In-System Equipment Chip Unprotect
The timing on these flowcharts is critical. Care should be taken to ensure that, where a
pause is specified, it is followed as closely as possible. Do not allow the microprocessor to
service interrupts that will upset the timing and do not abort the procedure before reaching
Figure 28.: Programmer Equipment Chip Unprotect Flowchart
Block protection
Flowchart.
Figure 27.: Programmer Equipment Block Protect
Figure 29.: In-System Equipment Block Protect
ID
) voltage levels on some of the bus pins. These
VIL, which give a summary of each
IL
, all along the Protect and Verify
and
Table 37.:
Figure 30.: