Disabling of the inputs can be used to take advantage of
the typical write cycle time. Once the stop condition is
issued to indicate the end of the host’s write operation,
CAT24CXXX initiates the internal write cycle. ACK poll-
ing can be initiated immediately. This involves issuing
the start condition followed by the slave address for a
write operation. If CAT24CXXX is still busy with the write
operation, no ACK will be returned. If
CAT24CXXX has completed the write operation, an
ACK will be returned and the host can then proceed with
the next read or write operation.
The Write Protection feature allows the user to protect
against inadvertent programming of the memory array.
If the WP pin is tied to VCC, the entire memory array is
Figure 9. Immediate Address Read Timing
protected and becomes read only. The CAT24CXXX
will accept both slave and byte addresses, but the
memory location accessed is protected from program-
ming by the device's failure to send an acknowledge
after the first byte of data is received.
The READ operation for the CAT24CXXX is initiated in
the same manner as the write operation with one excep-
tion, that R/W bit is set to one. Three different READ
operations are possible: Immediate/Current Address
READ, Selective/Random READ and Sequential READ.
BUS ACTIVITY: A
MASTER R ADDRESS
SDA LINE S
Doc. No. 25084-00 12/98