S-25C160A Datasheet, PDF (15/39 Pages) Seiko Instruments Inc – Write protect function during the low power supply

Rev.4.2_02_H
SPI SERIAL E²PROM
S-25C160A
3. Write disable (WRDI)
The WRDI instruction is one of ways to reset bit Write Enable Latch (WEL). After selecting the device by the chip select
( CS ), input the instruction code from serial data input (SI).
To reset bit WEL, set the device in the non-select status by CS at the 8th clock of the serial clock.
To cancel the WRDI instruction, input the clock different from a specified value (n = 8 clocks) while CS is in “L”. Bit
WEL is reset after the operations shown below.
• The power supply voltage is dropping
• Power-on
• After performing WRDI
• After the completion of Write operation by the WRSR instruction
• After the completion of Write operation by the WRITE instruction
CS
WP
High / Low
SCK
SI
SO
1
2
3
4
5
6
7
8
Instruction
High-Z
Figure 14 WRDI Operation
15