ST24/25C04, ST24/25W04
Figure 6. I
2
C Bus Protocol
SCL
SDA
START
CONDITION
SDA
INPUT
SDA
CHANGE
STOP
CONDITION
SCL
1
2
3
7
8
9
SDA
MSB
ACK
START
CONDITION
SCL
1
2
3
7
8
9
SDA
MSB
ACK
STOP
CONDITION
AI00792
Multibyte Write.
For the Multibyte Write mode, the
MODE pin must be at V
IH
. The Multibyte Write
mode can be started from any address in the
memory. The master sends from one up to 4 bytes
of data, which are each acknowledged by the mem-
ory. The transfer is terminated by the master gen-
erating a STOP condition. The duration of the write
cycle is t
W
= 10ms maximum except when bytes
are accessed on 2 rows (that is have different
values for the 6 most significant address bits A7-
A2), the programming time is then doubled to a
maximum of 20ms. Writing more than 4 bytes in the
Multibyte Write mode may modify data bytes in an
adjacent row (one row is 8 bytes long). However,
the Multibyte Write can properly write up to 8
consecutive bytes as soon as the first address of
these 8 bytes is the first address of the row, the 7
following bytes being written in the 7 following bytes
of this same row.
Page Write.
For the Page Write mode, the MODE
pin must be at V
IL
. The Page Write mode allows up
to 8 bytes to be written in a single write cycle,
provided that they are all located in the same ’row’
in the memory: that is the 5 most significant mem-
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STMICROELECTRONICS [ STMICROELECTRONICS ]
