BR24T128FVJ-W データシートの表示（PDF） - ROHM Semiconductor
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BR24T128FVJ-W Datasheet PDF : 37 Pages
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BR24T128-W
Datasheet
Write Command
1. Write Cycle
(1) Arbitrary data can be written to this 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 bytes is specified per device of each capacity. Up to 8 arbitrary bytes can be written.
SDA
LINE
S
W
T
R
A
I
R
SLAVE T
T
ADDRESS E
1 0 1 0 A2A1A0
1st WORD
ADDRESS
*
W A W AW A
* 13 12 11
RA
A
/C
C
WK
K
Figure 35. Byte Write Cycle
2nd WORD
ADDRESS
WA D7
0
A
C
K
S
T
DATA
O
P
D0
A
C
K
* Don't Care bit
SDA
LINE
S
W
T
R
A
I
R
SLAVE
T
T
ADDRESS
E
1st WORD
ADDRESS(n)
1 0 1 0 A2 A1 A0
WA WA WA
＊ ＊ 13 12 11
RA
/C
WK
2nd WORD
ADDRESS(n)
DATA(n)
WA
D7
D0
0
A
A
A
C
C
C
K
K
K
Figure 36. Page Write Cycle
S
T
O
DATA(n+63)
P
D0
A
C
K
* Don't Care bit
(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 BR24T128-W, where 2 or more bytes of data is intended to be written, after the 8
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 BR24T128-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).
2. Internal Address Increment
Page write mode (in the case of BR24T128-W)
WA7 WA6 WA5 WA4 WA3 WA2 WA1 WA0
00000000
00000001
00000010
Increment
3Eh 0
0
0
0111110
0111111
0000000
Significant bit is fixed.
No digit up
For example, when it is started from address 3Eh,
then, increment is made as below,
3Eh→3Fh→00h→01h･･･ please take note.
※3Eh･･･3E in hexadecimal, therefore,
00111110 becomes a binary number.
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 at 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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