25C040 MicrochipTechnology, 25C040 Datasheet - Page 8

• Manufacturer Part Number: 25C040
• Description: 4KSPIBusSerialEEPROM
• Manufacturer: MicrochipTechnology

25AA040/25LC040/25C040
3.4
The 25xx040 contains a write enable latch.
Table 3-3 for the Write Protect Functionality Matrix.
This latch must be set before any write operation will
be completed internally. The WREN instruction will set
the latch, and the WRDI will reset the latch.
FIGURE 3-4:
FIGURE 3-5:
DS21204A-page 8
Write Enable (WREN) and Write
Disable (WRDI)
WRITE ENABLE SEQUENCE
WRITE DISABLE SEQUENCE
SCK
SCK
CS
SO
CS
SO
SI
SI
0
0
0
0
0
0
1
1
See
Preliminary
high impedance
high impedance
0
0
2
2
0
0
3
3
0
0
The following is a list of conditions under which the
write enable latch will be reset:
• Power-up
• WRDI instruction successfully executed
• WRSR instruction successfully executed
• WRITE instruction successfully executed
• WP line is low
4
4
1
1
5
5
1
1 0
6
6
0
0
7
7
1997 Microchip Technology Inc.