AT25640A-10PI-2.7 データシートの表示（PDF） - Atmel Corporation
部品番号
コンポーネント説明
メーカー
AT25640A-10PI-2.7
Atmel Corporation
AT25640A-10PI-2.7 Datasheet PDF : 19 Pages
| |||
WRITE STATUS REGISTER (WRSR): The WRSR instruction allows the user to select one of
four levels of protection. The AT25080A/160A/320A/640A is divided into four array segments.
One-quarter, one-half, or all of the memory segments can be protected. Any of the data within
any selected segment will therefore be read-only. The block write protection levels and corre-
sponding status register control bits are shown in Table 8.
The three bits BP0, BP1, and WPEN are nonvolatile cells that have the same properties and
functions as the regular memory cells (e.g., WREN, tWC, RDSR).
Table 8. Block Write Protect Bits
Status
Register Bits
Level
BP1
BP0
AT25080A
0
0
0
None
1(1/4)
0
1
0300
−03FF
2(1/2)
1
0
0200
−03FF
3(All)
1
1
0000
−03FF
Array Addresses Protected
AT25160A
AT25320A
None
None
0600
−07FF
0C00
−0FFF
0400
−07FF
0800
−0FFF
0000
−07FF
0000
−0FFF
AT25640A
None
1800
−1FFF
1000
−1FFF
0000
−1FFF
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 block-
protected sections in the memory array are disabled. Writes are only allowed to sections of the
memory that are not block-protected.
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 9. WPEN Operation
WPEN
0
0
1
1
X
X
WP
X
X
Low
Low
High
High
WEN
0
1
0
1
0
1
Protected
Blocks
Protected
Protected
Protected
Protected
Protected
Protected
Unprotected
Blocks
Protected
Writable
Protected
Writable
Protected
Writable
Status
Register
Protected
Writable
Protected
Protected
Protected
Writable
8 AT25080A/160A/320A/640A
3401C–SEEPR–8/04
Share Link: