S-93C46B_1 Datasheet, PDF (18/50 Pages) Seiko Instruments Inc – 3-WIRE SERIAL E2PROM

3-WIRE SERIAL E²PROM
S-93C46B/56B/66B
Rev.7.0_00
5. Write enable (EWEN) and write disable (EWDS)
The EWEN instruction is an instruction that enables a write operation. The status in which a write operation is
enabled is called the program enable mode.
The EWDS instruction is an instruction that disables a write operation. The status in which a write operation is
disabled is called the program disable mode.
After CS goes high, input an instruction in the order of the start bit, EWEN or EWDS instruction, and address
(optional). Each mode becomes valid by inputting a low level to CS after the last address (optional) has been
input.
CS
Standby
SK
1 2 3 4 5 6 7 89
DI
c⁰
0
11 = EWEN
4Xs
00 = EWDS
Figure 19 Write Enable/Disable Timing (S-93C46B)
CS
Standby
SK
1 2 3 4 5 6 7 8 9 10 11
DI
c⁰
0
11 = EWEN
6Xs
00 = EWDS
Figure 20 Write Enable/Disable Timing (S-93C56B, S-93C66B)
(1) Recommendation for write operation disable instruction
It is recommended to implement a design that prevents an incorrect write operation when a write instruction
is erroneously recognized by executing the write operation disable instruction when executing instructions
other than write instruction, and immediately after power-on and before power off.
18
Seiko Instruments Inc.