CAT25080 Datasheet, PDF (5/17 Pages) Catalyst Semiconductor – 8-Kb and 16-Kb SPI Serial CMOS EEPROM

CAT25080, CAT25160
STATUS REGISTER
The Status Register, as shown in Table 2, contains a
number of status and control bits.
The ¯R¯D¯Y¯ (Ready) bit indicates whether the device is
busy with a write operation. This bit is automatically set
to 1 during an internal write cycle, and reset to 0 when
the device is ready to accept commands. For the host,
this bit is read only.
The WEL (Write Enable Latch) bit is set/reset by the
WREN/WRDI commands. When set to 1, the device is
in a Write Enable state and when set to 0, the device is
in a Write Disable state.
The BP0 and BP1 (Block Protect) bits determine which
blocks are currently write protected. They are set by the
user with the WRSR command and are non-volatile.
The user is allowed to protect a quarter, one half or the
entire memory, by setting these bits according to Table
3. The protected blocks then become read-only.
The WPEN (Write Protect Enable) bit acts as an enable
for the ¯W¯P¯ pin. Hardware write protection is enabled
when the ¯W¯P¯ pin is low and the WPEN bit is 1. This
condition prevents writing to the status register and to
the block protected sections of memory. While
hardware write protection is active, only the non-block
protected memory can be written. Hardware write
protection is disabled when the ¯W¯P¯ pin is high or the
WPEN bit is 0. The WPEN bit, ¯W¯P¯ pin and WEL bit
combine to either permit or inhibit Write operations, as
detailed in Table 4.
Table 2. Status Register
7
6
5
WPEN
0
0
4
3
2
1
0
0
BP1
BP0
WEL
¯R¯D¯Y¯
Table 3. Block Protection Bits
Status Register Bits
BP1
BP0
0
0
0
1
1
0
1
1
Array Address Protected
None
25080: 0300-03FF
25160: 0600-07FF
25080: 0200-03FF
25160: 0400-07FF
25080: 0000-03FF
25160: 0000-07FF
Protection
No Protection
Quarter Array Protection
Half Array Protection
Full Array Protection
Table 4. Write Protect Conditions
WPEN
¯W¯P¯
0
X
0
X
1
Low
1
Low
X
High
X
High
WEL
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
© 2006 Catalyst Semiconductor, Inc.
5
Characteristics subject to change without notice
Doc. No. 1122 Rev. A