参数资料
| 型号： | BR25S640F-WE2 |
| 厂商： | Rohm Semiconductor |
| 文件页数： | 12/19页 |
| 文件大小： | 0K |
| 描述： | IC EEPROM SPI 64KB 20MHZ 8-SOP |
| 标准包装： | 1 |
| 格式 - 存储器： | EEPROMs - 串行 |
| 存储器类型： | EEPROM |
| 存储容量： | 64K (8K x 8) |
| 速度： | 20MHz |
| 接口： | SPI 3 线串行 |
| 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： | 标准包装 |
| 其它名称： | BR25S640F-WE2DKR |
BR25S □□□ Series
Technical Note
● I/O peripheral circuits
In order to realize stable high speed operations, pay attention to the following input / output pin conditions.
○ Input pin pull up, pull down resistance
When to attach pull up, pull down resistance to EEPROM input pin, select an appropriate value for the microcontroller
VOL, IOL with considering VIL characteristics of this IC.
1. Pull up resistance
R PU ≧
V OLM ≦
V CC － V OLM
I OLM
V ILE
???①
???②
Microcontroller
V OLM
“L” output
I OLM
R PU
EEPROM
V ILE
“L” input
Example) When Vcc=5V, V ILE =1.5V, V OLM =0.4V, I OLM =2mA,
from the equation ① ,
5 － 0.4
R PU ≧
2×10 -3
∴ R PU ≧
2.3[k Ω ]
Fig.45 Pull up resistance
With the value of Rpu to satisfy the above equation, V OLM
becomes 0.4V or lower, and with V ILE (=1.5V), the equation ② is
also satisfied.
? V ILE :EEPROM V IL specifications
? V OLM :Microcontroller V OL specifications
? I OLM :Microcontroller I OL specifications
And, in order to prevent malfunction or erroneous write at power ON/OFF, be sure to make CSB pull up.
2.Pull down resistance
R PD ≧
V OHM
I OHM
???③
Microcontroller
EEPROM
V OHM ≧
V IHE
???④
V OHM
V IHE
Example) When V CC =5V, V OHM =V CC -0.5V, I OHM ＝ 0.4mA,
“H” output
I OHM
R PD
“H” input
R PD ≧
V IHE =V CC ×0.7V, from the equation ③,
5 － 0.5
0.4×10 -3
Fig.46
Pull down resistance
∴ R PD ≧
11.3[k Ω ]
0.2Vcc is input, operation speed becomes slow.
( 1 In this case, guaranteed value of operating timing is guaranteed.)
Further, by amplitude VIHE, VILE of signal input to EEPROM, operation speed changes. By inputting Vcc/GND level
amplitude of signal, more stable high speed operations can be realized. On the contrary, when amplitude of 0.8VCC /
*1
In order to realize more stable high speed operation, it is recommended to make the values of R PU , R PD as large as
possible, and make the amplitude of signal input to EEPROM close to the amplitude of VCC / GND level.
*
SO load capacity condition
Load capacity of SO output pin affects upon delay characteristic of SO output (Data output delay time, time from HOLDB
to High-Z, Output rise time, Output fall time.). In order to make output delay characteristic into better, make SO load
capacity small.
EEPROM
SO
C L
Fig.47 SO load capacity
○ Other cautions
Make the each wire length from the microcontroller to EEPROM input pin same length, in order to prevent setup / hold
violation to EEPROM, owing to difference of wire length of each input.
www.rohm.com
? 2010 ROHM Co., Ltd. All rights reserved.
12/18
2010.12 - Rev.B
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相关代理商/技术参数 |
参数描述 |
|---|---|
| BR25S640-W | 制造商:ROHM 制造商全称:Rohm 功能描述:High Reliability Series Serial EEPROMs |
| BR25S-E | 制造商:ROHM 制造商全称:Rohm 功能描述:High speed clock action up to 20MHz(Max.), Wait function by HOLDB terminal. |
| BR25XX0-10XU-1.8 | 制造商:ROHM 制造商全称:Rohm 功能描述:Supply voltage 1.8V~5.5V/Operating temperature -40C~+85C type |
| BR25XX0-10XU-2.7 | 制造商:ROHM 制造商全称:Rohm 功能描述:Supply voltage 2.7V~5.5V/Operating temperature -40C~+85C type |
| BR26 | 制造商:PANJIT 制造商全称:Pan Jit International Inc. 功能描述:MINI SURFACE MOUNT SCHOTTKY BARRIER RECTIFIER |
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