S-25A010A Datasheet, PDF (23/35 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
 Protect Operation
Table 21 shows the block settings of write protect. Setting value in Protect Bits (BP1, BP0) in the status register protect
data in the area of all / 50% / 25% of the memory address.
Setting WP pin to “L” provides the following settings.
• Write protect for the WRITE, WRSR instructions
• Reset bit WEL
The timing during the cycle write to the status register is showed in "Figure 8 Valid Timing in Write Protect" and
"Figure 9 Invalid Timing in Write Protect".
Status Register
BP1
BP0
0
0
0
1
1
0
1
1
Table 21 Block Settings of Write Protect
Area of Write Protect
Address of Write Protect Block
S-25A010A
S-25A020A
S-25A040A
0%
None
None
None
25%
60h to 7Fh
C0h to FFh
180h to 1FFh
50%
40h to 7Fh
80h to FFh
100h to 1FFh
100%
00h to 7Fh
00h to FFh
000h to 1FFh
 Hold Operation
The hold operation is used to pause serial communications without setting this IC in the non-select status. In the hold
status, the serial data output goes in "High-Z", and both of the serial data input and the serial clock go in "Don't care". Be
sure to set the chip select ( CS ) to "L" to set this IC in the select status during the hold status.
Generally, during the hold status, this IC holds the select status. But if setting this IC in the non-select status, the users
can finish the operation even in progress. Figure 22 shows the hold operation.
These are two statuses when the serial clock (SCK) is set to "L".
• If setting hold ( HOLD ) to "L", hold ( HOLD ) is switched at the same time the hold status starts.
• If setting hold ( HOLD ) to "H", hold ( HOLD ) is switched at the same time the hold status ends.
These are two statuses when the serial clock (SCK) is set to "H".
• If setting hold ( HOLD ) to "L", the hold status starts when the serial clock goes in "L" after hold ( HOLD ) is switched.
• If setting hold ( HOLD ) to "H", the hold status ends when the serial clock goes in "L" after hold ( HOLD ) is switched.
Hold status
Hold status
SCK
HOLD
Figure 22 Hold Operation
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