S-25A128B Datasheet, PDF (17/26 Pages) Seiko Instruments Inc – Write protect function during the low power supply voltage

Rev.1.3_01
FOR AUTOMOTIVE 125°C OPERATION SPI SERIAL E²PROM
S-25A128B
Table 17 Block Settings of Write Protect
Status Register
BP1
BP0
0
0
0
1
1
0
1
1
Area of Write Protect
0%
25%
50%
100%
Address of Write Protect Block
None
3000h to 3FFFh
2000h to 3FFFh
0000h to 3FFFh
Table 18 Protect Operation
Mode
WP Pin
1
Software Protect
1
(SPM)
X
X
Hardware Protect
0
(HPM)
0
Remark X = Don't care
Bit SRWD
X
X
0
0
1
1
Bit WEL
0
1
0
1
0
1
Write Protect Block
Write disable
Write disable
Write disable
Write disable
Write disable
Write disable
General Block
Write disable
Write enable
Write disable
Write enable
Write disable
Write enable
Status Register
Write disable
Write enable
Write disable
Write enable
Write disable
Write disable
 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 18 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 18 Hold Operation
17