CAT28C257 Datasheet, PDF (8/13 Pages) Catalyst Semiconductor – 256K-Bit CMOS PARALLEL E2PROM

CAT28C257
DATA Polling
DATA polling is provided to indicate the completion of
write cycle. Once a byte write or page write cycle is initiated,
attempting to read the last byte written will output the
complement of that data on I/O₇ (I/O₀–I/O₆ are
indeterminate) until the programming cycle is complete.
Upon completion of the self−timed write cycle, all I/O’s will
output true data during a read cycle.
Toggle Bit
In addition to the DATA Polling feature of the
CAT28C257, the device offers an additional method for
determining the completion of a write cycle. While a write
cycle is in progress, reading data from the device will result
in I/O₆ toggling between one and zero. However, once the
write is complete, I/O₆ stops toggling and valid data can be
read from the device.
ADDRESS
CE
WE
t_OEH
t_OE
OE
t_OES
Figure 8. DATA Polling
WE
CE
t_OEH
t_OE
OE
I/O₆
(Note 14)
Figure 9. Toggle Bit
14. Beginning and ending state of I/O₆ is indeterminate.
t_OES
(Note 14)
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