CMOS SERIAL E2PROM
S-93C46A/56A/66A
3. Write enable (EWEN) and Write disable (EWDS)
The EWEN instruction puts the S-93C46A/56A/66A into write enable mode, which accepts WRITE, ERASE, WRAL,
and ERAL instructions. The EWDS instruction puts the S-93C46A/56A/66A into write disable mode, which refuses WRITE,
ERASE, WRAL, and ERAL instructions.
The S-93C46A/56A/66A powers on in write disable mode, which protects data against unexpected, erroneous write
operations caused by noise and/or CPU malfunctions. It should be kept in write disable mode except when performing write
operations.
STANDBY
CS
1
2
3
4
5
6
7
8
9
SK
DI
1
0
0
4Xs
11=EWEN
00=EWDS
Figure 19 EWEN/EWDS Timing (S-93C46A)
STANDBY
CS
SK
1
2
3
4
5
6
7
8
9
10
11
1
0
0
DI
6Xs
11=EWEN
00=EWDS
Figure 20 EWEN/EWDS Timing (S-93C56A)
STANDBY
CS
SK
1
2
3
4
5
6
7
8
9
10
11
1
0
0
DI
6Xs
11=EWEN
00=EWDS
Figure 21 EWEN/EWDS Timing (S-93C66A)
Seiko Instruments Inc.
12
SII [ SEIKO INSTRUMENTS INC ]
