参数资料
型号: BR24S256F-WE2
厂商: Rohm Semiconductor
文件页数: 14/41页
文件大小: 0K
描述: IC EEPROM 256KBIT 100KHZ SOP8
标准包装: 2,500
格式 - 存储器: EEPROMs - 串行
存储器类型: EEPROM
存储容量: 256K (32K x 8)
速度: 400kHz
接口: I²C,2 线串口
电源电压: 1.7 V ~ 5.5 V
工作温度: -40°C ~ 85°C
封装/外壳: 8-SOIC(0.173",4.40mm 宽)
供应商设备封装: 8-SOP
包装: 带卷 (TR)
BR24L □□ -W Series,BR24S □□□ -W Series
Technical Note
● Software reset
Software reset is executed when to avoid malfunction after power on, and to reset during command input. Software reset
has several kinds, and 3 kinds of them are shown in the figure below. (Refer to Fig.48(a), Fig.48(b), and Fig.48(c).) In
dummy clock input area, release the SDA bus ('H' by pull up). In dummy clock area, ACK output and read data '0' (both 'L'
level) may be output from EEPROM, therefore, if 'H' is input forcibly, output may conflict and over current may flow, leading
to instantaneous power failure of system power source or influence upon devices.
Dummy clock×14
Start×2
SCL
1
2
13
14
Normal command
SDA
Normal command
Fig.48-(a) The case of dummy clock +START+START+ command input
Start
Dummy clock×9
Start
SCL
1
2
8
9
Normal command
SDA
Normal command
Fig.48-(b) The case of START +9 dummy clocks +START+ command input
Start×9
SCL
1
2
3
7
8
9
Normal command
SDA
*
Normal command
Start command from START input.
Fig.48-(c) START×9+ command input
● Acknowledge polling
During internal write execution, all input commands are ignored, therefore ACK is not sent back. During internal automatic
write execution after write cycle input, next command (slave address) is sent, and if the first ACK signal sends back 'L', then
it means end of write action, while if it sends back 'H', it means now in writing. By use of acknowledge polling, next command
can be executed without waiting for tWR = 5ms.
When to write continuously, R/W = 0, when to carry out current read cycle after write, slave address R/W = 1 is sent, and if
ACK signal sends back 'L', then execute word address input and data output and so forth.
During internal write,
First write command
ACK = HIGH is sent back.
S
T
A
R
T
Write command
S
T
O
P
S
T Slave
A
R address
T
A
C
K
H
S
T Slave
A
R address
T
A
C
K
H
t WR
Second write command
S
T Slave
A
R address
T
A
C
K
H
S
T Slave
A
R address
T
A
C Word
K address
L
A
C
K
L
Data
A
C
K
L
S
T
O
P
t WR
After completion of internal write,
ACK=LOW is sent back, so input next
word address and data in succession.
Fig.49 Case to continuously write by acknowledge polling
www.rohm.com
? 2009 ROHM Co., Ltd. All rights reserved.
14/40
2009.09 - Rev.D
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