Datasheet
Technical Note
8/21
BR24T□□□-W Series
www.rohm.com
2011.1 - Rev.H
© 2011 ROHM Co., Ltd. All rights reserved.
●Write Command
○Write cycle
・Arbitrary data is written to EEPROM. When to write only 1 byte, byte write is normally used, and when to write continuous data of 2 bytes or
more, simultaneous write is possible by page write cycle. The maximum number of write bytes is specified per device of each capacity.
p to 256 arbitrary bytes can be written.（In the case of BR24T1M-W）
・Data is written to the address designated by word address (n-th address)
・By issuing stop bit after 8bit data input, write to memory cell inside starts.
・When internal write is started, command is not accepted for tWR (5ms at maximum).
・By page write cycle, the following can be written in bulk : Up to 8Byte (BR24T01-W, BR24T02-W）
Up to 16Byte (BR24T04-W, BR24T08-W, BR24T16-W）
Up to 32Byte (BR24T32-W, BR24T64-W）
Up to 64Byte (BR24T128-W, BR24T256-W）
Up to 128Byte (BR24T512-W）
Up to 256Byte (BR24T1M-W）
And when data of the maximum bytes or higher is sent, data from the first byte is overwritten.
(Refer to "Internal address increment" of "Notes on page write cycle" in P10.)
・ As for page write cycle of BR24T01-W and BR24T02-W, after the significant 4 bits (in the case of BR24T01-W) of
word address, or the significant 5 bits (in the case of BR24T02-W) of word address are designated arbitrarily, by
continuing data input of 2 bytes or more, the address of insignificant 3 bits is incremented internally, and data up to 8
bytes can be written.
・ As for page write command of BR24T04-W, BR24T08-W and BR24T16-W, after page select bit ’P0’(in the case of
BR24T04-W), after page select bit ’P0,P1’(in the case of BR24T08-W), after page select bit ’P0,P1,P2’(in the case of
BR24T16-W) of slave address are designated arbitrarily, by continuing data input of 2 bytes or more, the address of
insignificant 4 bits is incremented internally, and data up to 16 bytes can be written.
・
As for page write cycle of BR24T32-W and BR24T64-W, after the significant 7 bits (in the case of BR24T32-W) of
word address, or the significant 8 bits (in the case of BR24T64-W) of word address are designated arbitrarily, by
continuing data input of 2 bytes or more, the address of insignificant 5 bits is incremented internally, and data up to
32 bytes can be written.
・
As for page write cycle of BR24T128-W and BR24T256-W, after the significant 8 bits (in the case of BR24T128-W)
of word address, or the significant 9 bits (in the case of BR24T256-W) of word address are designated arbitrarily, by
continuing data input of 2 bytes or more, the address of insignificant 6 bits is incremented internally, and data up to
64 bytes can be written.
W
R
I
T
E
S
T
A
R
T
R
/
W
A
C
K
S
T
O
P
WORD
ADDRESS(n)
DATA(n)
SDA
LINE
A
C
K
A
C
K
DATA(n+15)
A
C
K
SLAVE
ADDRESS
1
0
0
1A0 A1 A2
WA
7
D0 D7 D0
注 )
WA
0
A1 A2
WA
7
D7
1 1 0 0
W
R
I
T
E
S
T
A
R
T
R
/
W
S
T
O
P
WORD
ADDRESS
DATA
SLAVE
ADDRESS
A0
WA
0
D0
A
C
K
SDA
LINE
A
C
K
A
C
K
Note)
Fig.33 Byte write cycle (BR24T01/02/04/08/16-W)
A1 A2
WA
14
1 1 0 0
W
R
I
T
E
S
T
A
R
T
R
/
W
S
T
O
P
1st WORD
ADDRESS
DATA
SLAVE
ADDRESS
A0 D0
A
C
K
SDA
LINE
A
C
K
A
C
K
Note)
WA
13
WA
12
WA
11
WA
0
A
C
K
2nd WORD
ADDRESS
D7
*1
WA
15
*1 As for WA12, BR24T32-W becomes Don't care.
As for WA13, BR24T32/64-W becomes Don't care.
As for WA14, BR24T32/64/128-W becomes Don't care.
As for WA15, BR24T32/64/128/256-W becomes Don't care.
Fig.34
Byte write cycle (BR24T32/64/128/256/512/1M-W)
Fig.35
Page write cycle (BR24T01/02/04/08/16-W)
Fig.36
Page write cycle (BR24T32/64/128/256/512/1M-W)
*1 As for WA12, BR24T32-W becomes Don't care.
As for WA13, BR24T32/64-W becomes Don't care.
As for WA14, BR24T32/64/128-W becomes Don't care.
As for WA15, BR24T32/64/128/256-W becomes Don't care.
*2 As for BR24T256-W becomes (n+63)
As for BR24T512-W becomes (n+127)
As for BR24T1M-W becomes (n+255)
W
R
I
T
E
S
T
A
R
T
R
/
W
A
C
K
S
T
O
P
1st WORD
ADDRESS(n)
SDA
LINE
A
C
K
A
C
K
DATA(n+31)
A
C
K
SLAVE
ADDRESS
1
0
0
0
1
0
A0 A1 A2
WA
14
D0
注
)
*1
DATA(n)
D0D7
A
C
K
2nd WORD
ADDRESS(n)
WA
0
WA
13
WA
12
WA
11
*2
As for WA7, BR24T01-W becomes Don't care.
*1
As for WA7, BR24T01-W becomes Don't care.
*2
As for BR24T01/02-W becomes (n+7)
*2
*1
WA
15