收藏本站
BR24T □□□□ Series
Technical Note
In I C BUS, it is recommended that SDA port is of open drain input/output. However, when to use CMOS input / output of
● Cautions on microcontroller connection
R S
2
tri state to SDA port, insert a series resistance Rs between the pull up resistance Rpu and the SDA terminal of EEPROM.
This is controls over current that occurs when PMOS of the microcontroller and NMOS of EEPROM are turned ON
simultaneously. Rs also plays the role of protection of SDA terminal against surge. Therefore, even when SDA port is
open drain input/output, Rs can be used.
ACK
SCL
R PU
R S
SDA
'H' output of microcontroller
'L' output of EEPROM
Microcontroller
EEPROM
Over current flows to SDA line by 'H'
output of microcontroller and 'L'
output of EEPROM.
Fig.53 I/O circuit diagram
Fig.54 Input / output collision timing
○ Maximum value of Rs
The maximum value of Rs is determined by the following relations.
① SDA rise time to be determined by the capacity (CBUS) of bus line of Rpu and SDA should be tR or below.
And AC timing should be satisfied even when SDA rise time is late.
② The bus electric potential A to be determined by Rpu and Rs the moment when EEPROM outputs 'L' to SDA bus
sufficiently secure the input 'L' level (V IL ) of microcontroller including recommended noise margin 0.1Vcc.
V CC
? V CC ? V OL ? ? V OL ? 0 . 1 V CC ? V IL
R PU ? R S
R PU
R S
A
V OL
? R S ?
? V CC ? V OL ? ? R PU
1 . 1 V CC ? V IL
I OL
Bus line
Ex) V CC =3V
V IL =0.3V CC V OL =0.4V R PU =20k Ω
V IL
capacity
CBUS
Micro controller
EEPROM
R S ?
0 . 3 ? 3 ? 0 . 4 ? 0 . 1 ? 3
1 . 1 ? 3 ? 0 . 3 ? 3
? 20 ? 10 3
Fig.55 I/O Circuit Diagram
? 1 . 67 [ k Ω ]
○ Minimum value of Rs
The minimum value of Rs is determined by over current at bus collision. When over current flows, noises in power source
line, and instantaneous power failure of power source may occur. When allowable over current is defined as I, the
following relation must be satisfied. Determine the allowable current in consideration of impedance of power source line
in set and so forth. Set the over current to EEPROM 10mA or below.
R PU
R S
'L'output
V CC
R S
? R S ?
? I
V CC
I
Over current I
EX) V CC =3V I=1mA
'H' output
R S ?
3
10 ? 10 ? 3
Microcontroller
EEPROM
Fig.56 I/O circuit diagram
? 300 [ Ω ]
www.rohm.com
? 2011 ROHM Co., Ltd. All rights reserved.
15/21
2011.03 - Rev.A
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
BR25L640F-WE2 IC EEPROM SER 64KB SPI BUS 8SOP
BR25S128GUZ-WE2 IC EEPROM SPI 128KB 12-WLCSP
BR25S256F-WE2 IC EEPROM SPI 256KB 20MHZ 8-SOP
BR34E02FVT-WE2 IC EEPROM SPD 2KB I2C 8TSSOP
BR34L02FV-WE2 IC EEPROM 2KBIT 400KHZ 8SSOP
BR93L76RFVJ-WE2 IC EEPROM 8KBIT 2MHZ 8TSSOP
BS08D-112 TRIGGER BILTRL SW 175MA TO-92
BU04P-TZ-S TZ CONN 4 POS SINGLE ROW
相关代理商/技术参数
BR24T256FVWGE2 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Serial EEPROMs
BR24T256FVWGTR 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Serial EEPROMs
BR24T256F-WE2 功能描述:电可擦除可编程只读存储器 Hi-Rel Serial 电可擦除可编程只读存储器 of I2C BUS RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
BR24T256FWGE2 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Serial EEPROMs
BR24T256FWGTR 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Serial EEPROMs
BR24T256NUXWGE2 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Serial EEPROMs
BR24T256NUXWGTR 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Serial EEPROMs
BR24T256-W 制造商:ROHM Semiconductor 功能描述: