S-25A010A Datasheet, PDF (15/35 Pages) Seiko Instruments Inc – Write protect function during the low power supply voltage

Rev.5.2_01
FOR AUTOMOTIVE 125°C OPERATION SPI SERIAL E²PROM
S-25A010A/020A/040A
1. 3 WIP (b0) : Write In Progress
Bit WIP is a read only bit. It indicates whether the internal memory is in the write operation or not by the WRITE or
WRSR instruction. Bit WIP is "1" during the write operation but "0" during any other status. Figure 11 shows the
usage example.
CS
WRITE or WRSR instruction
RDSR instruction
D2 D1 D0
RDSR
SI
RDSR instruction
RDSR
RDSR instruction
RDSR
BB
BB
BB
PP
PP
PP
10
10
10
SO
1111 11
1111 11
1111
00
WEL, WIP
WEL, WIP
WEL, WIP
tPR
Figure 11 Usage Example of WEL, WIP Bits during Write
2. Write enable (WREN)
Before writing data (WRITE and WRSR), be sure to set bit Write Enable Latch (WEL). This instruction is to set bit
WEL. Its operation is below.
After selecting this IC by the chip select ( CS ), input the instruction code from serial data input (SI). To set bit WEL,
set this IC in the non-select status by CS at the 8th clock of the serial clock (SCK). To cancel the WREN instruction,
input the clock different from a specified value (n = 8 clock) while CS is in "L".
CS
WP
High
SCK
SI
1
2
3
4
5
6
7
8
Instruction
X
SO
Remark X = Don't care.
High-Z
Figure 12 WREN Operation
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