M29W640FB データシートの表示（PDF） - STMicroelectronics

部品番号

コンポーネント説明

メーカー

M29W640FB

64 Mbit (8Mb x8 or 4Mb x16, Page, Boot Block) 3V Supply Flash Memory

STMicroelectronics 

4 Command Interface

M29W640FT, M29W640FB

4.3 Block Protection commands

4.3.1

Enter Extended Block command

The device has an extra 256 Byte block (Extended Block) that can only be accessed using the

Enter Extended Block command. Three Bus write cycles are required to issue the Extended

Block command. Once the command has been issued the device enters Extended Block mode

where all Bus Read or Write operations to the Boot Block addresses access the Extended

Block. The Extended Block (with the same address as the Boot Blocks) cannot be erased, and

can be treated as one-time programmable (OTP) memory. In Extended Block mode the Boot

Blocks are not accessible.

To exit from the Extended Block mode the Exit Extended Block command must be issued.

The Extended Block can be protected, however once protected the protection cannot be

undone.

4.3.2

Exit Extended Block command

The Exit Extended Block command is used to exit from the Extended Block mode and return

the device to Read mode. Four Bus Write operations are required to issue the command.

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