MX29LV400T/B
CHIP UNPROTECT
The MX29LV400T/B also features the chip unprotect
mode, so that all sectors are unprotected after chip
unprotectiscompletedtoincorporateanychangesinthe
code. It is recommended to protect all sectors before
activating chip unprotect mode.
Toactivatethismode,theprogrammingequipmentmust
forceVIDoncontrolpinOEandaddresspinA9. TheCE
pins must be set at VIL. Pins A6 must be set to VIH.(see
Table2) Refertochipunprotect algorithmandwaveform
for the chip unprotect algorithm. The unprotection
mechanism begins on the falling edge of the WE pulse
and is terminated on the rising edge.
It is also possible to determine if the chip is unprotected
in the system by writing the Read Silicon ID command.
PerformingareadoperationwithA1=VIH,itwillproduce
00H at data outputs(Q0-Q7) for an unprotected sector.
It is noted that all sectors are unprotected after the chip
unprotect algorithm is completed.
P/N:PM0710
REV. 1.4, NOV. 23, 2001
17
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