![](http://datasheet.mmic.net.cn/280000/X4C105V20_datasheet_16104559/X4C105V20_5.png)
X4C105
Characteristics subject to change without notice.
5 of 19
REV 1.0.1 6/14/01
www.xicor.com
SERIAL WRITE OPERATIONS
Byte Write
For a write operation, the device requires the slave
address byte and a word address byte. This gives the
master access to any one of the words in the array.
After receipt of the word address byte, the device
responds with an acknowledge, and awaits the next
eight bits of data. After receiving the 8 bits of the data
byte, the device again responds with an acknowledge.
The master then terminates the transfer by generating
a stop condition, at which time the device begins the
internal write cycle to the nonvolatile memory. During
this internal write cycle, the device inputs are disabled,
so the device will not respond to any requests from the
master. The SDA output is at high impedance. See Fig-
ure 5.
An attempted write to a protected block of memory will
suppress the acknowledge bit and the operation will
terminate.
Page Write
The device is capable of a page write operation. It is
initiated in the same manner as the byte write opera-
tion; but instead of terminating the write cycle after the
first data byte is transferred, the master can transmit
an unlimited number of 8-bit bytes. After the receipt of
each byte, the device will respond with an acknowl-
edge, and the address is internally incremented by
one. The page address remains constant. When the
counter reaches the end of the page, it “rolls over” and
goes back to ‘0’ on the same page. This means that the
master can write 16 bytes to the page starting at any
location on that page. If the master begins writing at
location 10, and loads 12 bytes, then the first 5 bytes
are written to locations 10 through 15, and the last 7
bytes are written to locations 0 through 6. Afterwards,
the address counter would point to location 7 of the page
that was just written. See Figure 6. If the master supplies
more than 16 bytes of data, then new data over-writes
the previous data, one byte at a time.
Figure 5. Byte Write Sequence
Figure 6. Writing 12 bytes to a 16-byte page starting at location 10.
S
t
a
r
t
S
t
o
p
Slave
Address
Byte
Address
Data
A
C
K
A
C
K
A
C
K
SDA Bus
Signals from
the Slave
Signals from
the Master
0
Address
n-1
Address
10
5 Bytes
7 Bytes
Address
= 6
Address Pointer
Ends Here
Addr = 7