S-25A128B Datasheet, PDF (12/26 Pages) Seiko Instruments Inc – Write protect function during the low power supply voltage

FOR AUTOMOTIVE 125°C OPERATION SPI SERIAL E²PROM
S-25A128B
CS
Rev.1.3_01
WP
High / Low
SCK
SI
1
2
3
4
5
6
7
8
Instruction
High-Z
SO
Figure 11 WREN Operation
3. Write disable (WRDI)
The WRDI instruction is one of ways to reset bit Write Enable Latch (WEL). After selecting this IC by the chip select
( CS ), input the instruction code from serial data input (SI).
To reset bit WEL, set this IC 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 clock) while CS is in "L".
Bit WEL is reset after the operations shown below.
• The power supply voltage is dropping
• At 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
12
1
2
3
4
5
6
7
8
Instruction
High-Z
Figure 12 WRDI Operation