PM25LV512-25QCE Просмотр технического описания (PDF) - PMC-Sierra

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производитель

PM25LV512-25QCE

512 Kbit / 1 Mbit 3.0 Volt-only, Serial Flash Memory With 25 MHz SPI Bus Interface

PMC-Sierra 

PMC

Pm25LV512/010

Table 5. Block Write Protect Bits

Level

0

1(1/4)

2(1/2)

3(All)

Status Register Bits

BP1

BP0

0

0

0

1

1

0

1

1

Pm25LV512

Array Addresses

Locked Out

Locked-out

Block(s)

None

None

000000-00FFFF

All Blocks

(1 - 2)

Pm25LV010

Array Addresses

Locked Out

Locked-out

Block(s)

None

None

018000 - 01FFFF

Block 4

010000 - 01FFFF

Block 3, 4

000000 - 01FFFF

All Blocks

(1 - 4)

The WRSR instruction also allows the user to enable or disable the Write Protect (WP#) pin through the use of the

Write Protect Enable (WPEN) bit. Hardware write protection is enabled when the WP# pin is low and the WPEN bit

is "1". Hardware write protection is disabled when either the WP# pin is high or the WPEN bit is "0." When the

device is hardware write protected, writes to the Status Register, including the Block Protect bits and the WPEN

bit, and the locked-out blocks in the memory array are disabled. Write is only allowed to blocks of the memory

which are not locked out. The WRSR instruction is self-timed to automatically erase and program BP0, BP1, and

WPEN bits. In order to write the status register, the device must first be write enabled via the WREN instruction.

Then, the instruction and data for the three bits are entered. During the internal write cycle, all instructions will be

ignored except RDSR instructions. The Pm25LV512/010 will automatically return to write disable state at the

completion of the WRSR cycle.

Note: When the WPEN bit is hardware write protected, it cannot be changed back to "0", as long as the WP# pin

is held low.

Table 6. WPEN Operation

WPEN

0

0

1

1

X

X

WP

X

X

Low

Low

High

High

WEN

0

1

0

1

0

1

ProtectedBlocks

Protected

Protected

Protected

Protected

Protected

Protected

UnprotectedBlocks

Protected

Writable

Protected

Writable

Protected

Writable

Status Register

Protected

Writable

Protected

Protected

Protected

Writable

Programmable Microelectronics Corp.

9

Issue Date: December, 2003, Rev: 1.3

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