
X24C01 
5 
WRITE OPERATIONS 
Byte Write  
To  initiate  a  write  operation,  the  master  sends  a  start 
condition followed by a seven bit word address and a write 
bit. The X24C01 responds with an acknowledge, then waits 
for eight bits of data and then responds with an 
acknowledge. The master then terminates the transfer by 
generating a stop condition, at which time the X24C01 
begins the internal write cycle to the nonvolatile memory. 
While the internal write cycle is in progress, the X24C01 
inputs are disabled, and the device will not respond to any 
requests  from  the  master.  Refer  to  Figure  4  for  the 
address, acknowledge and data transfer sequence. 
Page Write  
The most significant five bits of the word address define 
the page address. The X24C01 is capable of a four byte page 
write operation. It is initiated in the same manner as 
the byte write operation, but instead of terminating the 
transfer of data after the first data byte, the master can 
transmit up to three more bytes. After the receipt of each data 
byte, the X24C01 will respond with an acknowledge. 
After the receipt of each data byte, the two low order address 
bits are internally incremented by one. The high 
order  five  bits  of  the  address  remain  constant.  If  the 
master should transmit more than four data bytes prior 
to generating the stop condition, the address counter will “roll 
over” and the previously transmitted data will be 
overwritten. As with the byte write operation, all inputs are 
disabled until completion of the internal write cycle. 
Refer to Figure 5 for the address, acknowledge and data 
transfer sequence. 
Figure 4.  Byte Write 
BUS ACTIVITY: 
SDA LINE 
BUS ACTIVITY: 
X24C01 
S 
T 
A 
R 
T 
WORD 
ADDRESS (n) 
S 
T 
O 
P 
P 
A 
C 
K 
DATA n 
R   
/ 
W 
L  
S 
B 
S 
M 
S 
B 
A 
C 
K 
3837 FHD F09 
Figure 5.  Page Write 
BUS ACTIVITY: 
SDA LINE 
BUS ACTIVITY: 
X24C01 
S 
T 
A 
R 
T 
S 
S 
T 
O 
P 
P 
A 
C 
K 
A 
C 
K 
A 
C 
K 
M 
S 
B 
WORD 
ADDRESS (n) 
DATA n 
DATA n+1 
DATA n+3 
A 
C 
K 
R   
/ 
W 
L  
S 
B 
3837 FHD F10