Datasheet
BR24G256-3
Write Command
1. Write Cycle
(1) Arbitrary data can be written to EEPROM. When writing only 1 byte, Byte Write is normally used, and when
writing 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. Up to 64 arbitrary bytes can be written.
S
T
A
R
T
W
R
I
T
E
S
T
O
P
SLAVE
ADDRESS
1st WORD
ADDRESS
2nd WORD
ADDRESS
DATA
SDA
LINE
WA WA WAWA
14 13 12 11
WA
0
1
0
1
0 A2A1A0
D7
D0
* Don't Care bit
*
A
C
K
A
C
K
A
C
K
R
/
W
A
C
K
Figure 35. Byte Write Cycle
S
T
A
R
T
W
R
I
T
E
S
T
O
P
SLAVE
ADDRESS
1st WORD
ADDRESS(n)
2nd WORD
ADDRESS(n)
DATA(n)
DATA(n+63)
SDA
LINE
WA WA WA WA
14 13 12 11
WA
0
1
0
1
A2 A1A0
D7
D0
D0
0
*
* Don't Care Bit
A
C
K
R
/
W
A
C
K
A
C
K
A
C
K
A
C
K
Figure 36. Page Write Cycle
(2) During internal write execution, all input commands are ignored, therefore ACK is not returned.
(3) Data is written to the address designated by word address (n-th address)
(4) By issuing stop bit after 8bit data input, internal write to memory cell starts.
(5) When internal write is started, command is not accepted for tWR (5ms at maximum).
(6) Using page write cycle, writing in bulk is done as follows: When data of more than 64 bytes is sent, the bytes in
excess overwrite the data already sent first.
(Refer to "Internal Address Increment")
(7) As for page write cycle of BR24G256-3, where 2 or more bytes of data is intended to be written, after the 9
significant bits of word address are designated arbitrarily, only the value of 6 least significant bits in the address
is incremented internally, so that data up to 64 bytes of memory only can be written.
In the case BR24G256-3, 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)
2. Internal Address Increment
Page write mode (in the case of BR24G256-3)
WA7 WA6 WA5 WA4 WA3 WA2 WA1 WA0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
Increment
For example, when it is started from address 3Eh,
then, increment is made as below,
3Eh→3Fh→00h→01h･･･ please take note.
0
0
0
0
0
0
1
1
0
1
1
0
1
1
0
1
1
0
1
1
0
0
1
0
3Eh
※3Eh･･･3E in hexadecimal, therefore,
00111110 becomes a binary number.
Significant bit is fixed.
No digit up
3. Write Protect (WP) Terminal
Write Protect (WP) Function
When WP terminal is set at 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 leave it open.
In case of using it as ROM, it is recommended to connect it to pull up or Vcc.
At extremely low voltage at power ON/OFF, by setting the WP terminal ‘H’, write error can be prevented.
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25.Feb.2013 Rev.002
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