X24C02 Datasheet, PDF (5/16 Pages) Xicor Inc. – Serial E2PROM

X24C02
DEVICE ADDRESSING
Following a start condition the master must output the
address of the slave it is accessing. The most significant
four bits of the slave are the device type identifier (see
Figure 4). For the X24C02 this is fixed as 1010[B].
Figure 4. Slave Address
DEVICE TYPE
IDENTIFIER
1 0 1 0 A2 A1 A0 R/W
DEVICE
ADDRESS
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The next three significant bits address a particular
device. A system could have up to eight X24C02 devices
on the bus (see Figure 10). The eight addresses are
defined by the state of the A₀, A₁ and A₂ inputs.
The last bit of the slave address defines the operation to
be performed. When set to one a read operation is
selected, when set to zero a write operations is selected.
Figure 5. Byte Write
Following the start condition, the X24C02 monitors the
SDA bus comparing the slave address being transmit-
ted with its slave address (device type and state of A₀,
A₁ and A₂ inputs). Upon a correct compare the X24C02
outputs an acknowledge on the SDA line. Depending on
the state of the R/W bit, the X24C02 will execute a read
or write operation.
WRITE OPERATIONS
Byte Write
For a write operation, the X24C02 requires a second
address field. This address field is the word address,
comprised of eight bits, providing access to any one of
the 256 words of memory. Upon receipt of the word
address the X24C02 responds with an acknowledge,
and awaits the next eight bits of data, again responding
with an acknowledge. The master then terminates the
transfer by generating a stop condition, at which time the
X24C02 begins the internal write cycle to the nonvolatile
memory. While the internal write cycle is in progress the
X24C02 inputs are disabled, and the device will not
respond to any requests from the master. Refer to
Figure 5 for the address, acknowledge and data transfer
sequence.
S
T
BUS ACTIVITY: A
MASTER
R
T
SLAVE
ADDRESS
WORD
ADDRESS
S
DATA
T
O
P
SDA LINE
S
P
BUS ACTIVITY:
X24C02
A
A
A
C
C
C
K
K
K
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Figure 6. Page Write
S
T
BUS ACTIVITY: A
MASTER
R
T
SDA LINE
S
BUS ACTIVITY:
X24C02
SLAVE
ADDRESS
WORD
ADDRESS (n)
A
A
C
C
K
K
DATA n
DATA n+1
A
A
C
C
K
K
NOTE: In this example n = xxxx 000 (B); x = 1 or 0
S
DATA n+3
T
O
P
P
A
C
K
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