25AA128/25LC128
2.4 Write Enable (WREN) and Write
Disable (WRDI)
The 25XX128 contains a write enable latch. See
Table 2-4 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.
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
FIGURE 2-4: WRITE ENABLE SEQUENCE (WREN)
CS
SCK
01234567
SI
00000110
High-Impedance
SO
FIGURE 2-5: WRITE DISABLE SEQUENCE (WRDI)
CS
SCK
01234567
SI
000001
00
High-Impedance
SO
© 2007 Microchip Technology Inc.
DS21831C-page 9