Datasheet
Technical Note
10/21
BR24T□□□-W Series
www.rohm.com
2011.1 - Rev.H
© 2011 ROHM Co., Ltd. All rights reserved.
○
Notes on write cycle continuous input
○Notes on page write cycle
List of numbers of page write
Number of
Pages
8Byte 16Byte 32Byte 64Byte 128Byte 256Byte
Product
number
BR24T01-W
BR24T02-W
BR24T04-W
BR24T08-W
BR24T16-W
BR24T32-W
BR24T64-W
BR24T128-W
BR24T256-W
BR24T512-W BR24T1M-W
The above numbers are maximum bytes for respective types.
Any bytes below these can be written.
In the case BR24T256-W, 1 page=64bytes, but the page
write cycle time is 5ms at maximum for 64byte bulk write.
It does not stand 5ms at maximum × 64byte=320ms(Max.)
○Internal address increment
Page write mode (in the case of BR24T16-W）
○Write protect (WP) terminal
・Write protect (WP) function
When WP terminal is set Vcc (H level), data rewrite of all addresses is prohibited. When it is set GND (L level), data rewrite of all
address is enabled. Be sure to connect this terminal to Vcc or GND, or control it to H level or L level. Do not use it open.
At extremely low voltage at power ON / OFF, by setting the WP terminal 'H', mistake write can be prevented.
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
DATA(n+15)
A
C
K
SLAVE
ADDRESS
10 0 1
P0
P1
P2
WA
7
D0 D7 D0
A
C
K
WA
0
1 100
Next command
tWR (maximum : 5ms)
Command is not accepted for this period
At STOP(stop bit),
write starts.
S
T
A
R
T
Note)
*1
*2
Fig.39 Page write cycle (BR24T32/64/128/256/512/1M-W)
Fig.38 Page write cycle (BR24T01/02/04/08/16-W)
For example, when it is started from address 0Eh,
therefore, increment is made as below,
0Eh→0Fh→00h→01h･･･ which please note.
※0Eh･･･0E in hexadecimal, therefore, 00001110 becomes a
binary number.
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
1A0 A1 A2
WA
14
D0
*1
DATA(n)
D0 D7
A
C
K
2nd WORD
ADDRESS(n)
WA
0
WA
13
WA
12
WA
11
WA
15
*2
1 0 1
0
ｔWR(maximum：5ms)
Command is not accepted for this period
Next command
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
1A0 A1 A2
WA
14
D0
Note)
*1
DATA(n)
D0 D7
A
C
K
2nd WORD
ADDRESS(n)
WA
0
WA
13
WA
12
WA
11
*2
1 0 1
At STOP (stop bit)
write starts.
S
T
A
R
T
*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)
*1 As for WA7, BR24T01-W becomes Don’t care.
*2 BR24T01/02-W become (n+7)
WA7 WA4 WA3 WA2 WA1 WA0
0 00000
0 00001
0 00010
0 01110
0 01111
0 00000
Increment
0Eh
Significant bit is fixed.
No digit up