BU9891GUL-W Rohm, BU9891GUL-W Datasheet - Page 14

• Manufacturer Part Number: BU9891GUL-W
• Description: WL-CSP EEPROM family Microwire Bus
• Manufacturer: Rohm

© 2010 ROHM Co., Ltd. All rights reserved.
BU9891GUL-W
www.rohm.com
○Selection of resistance value R
The resistance R becomes through current limit resistance at data collision. When through current flows, noises of
power source line and instantaneous stop of power source may occur. When allowable through current is defined as I,
the following relation should be satisfied. Determine allowable current amount in consideration of impedance and so
forth of power source line in set. And insert resistance R, and set the value R to satisfy EEPROM input level VIH/VIL
even under influence of voltage decline owing to leak current and so forth. Insertion of R will not cause any influence
upon basic operations.
(1) Address data A0 = “1” input, dummy bit “0” output timing
(2) DO status READY output timing
(When microcontroller DI/O output is “H”, EEPROM DO outputs “L”, and “H” is input to DI)
・Make the through current to EEPROM 10mA or below.
・See to it that the level VIH of EEPROM should satisfy the following.
(When the microcontroller DI/O is “L”, EEPROM DO output “H”, and “L” is input to DI)
・Set the EEPROM input level VIL so as to satisfy the following.
Example) When Vcc=5V, VOHM=5V, IOHM=0.4mA, VOLM=5V, IOLM=0.4mA,
Fig.54 Circuit at DI, DO direct connection (Microcontroller DI/O “L” output, EEPROM “H” output)
Fig.53 Circuit at DI, DO direct connection (Microcontroller DI/O “H” output, EEPROM “L” output)
Microcontroller
Microcontroller
“H” output
“L” output
∴
From the equation ⑦,
R ≧
R ≧
R ≧ 12.5 [kΩ]
DI/O PORT
DI/O PORT
VOHM
VOLM
IOHM
IOHM
0.4×10
VOHM
IOHM
5
VOLE
VOHE
R
R
-3
DO
DO
DI
DI
・・・⑨
EEPROM
EEPROM
“H” output
“L” output
14/17
From the equation⑧,
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∴
Therefore, from the equations ⑨ and ⑩,
∴
R ≧
R ≧
R ≧ 2.2 [kΩ]
R ≧ 12.5 [kΩ]
Conditions
At this moment, if VOLE=0V,
As this moment, VOHE=Vcc
Conditions
・VIHE
・VOLE
・VOHM
・IOHM
・VILE
・VOHE
・VOLM
・IOLM
Vcc – VOLM
2.1×10
5 – 0.4
IOLM
∴
∴
VOHM ≦ VIHE
VOHM ≦ IOHM×R + VOLE
VOHM ≦ IOHM×R
VOLM ≧ VILE
VOLM ≧ VOHE – IOLM×R
VOLM ≧ Vcc – IOLM×R
-3
: EEPROM VIH specifications
: EEPROM VOL specifications
: Microcontroller VOH specifications
: Microcontroller IOH specifications
: EEPROM VIL specifications
: EEPROM VOH specifications
: Microcontroller VOL specifications
: Microcontroller IOL specifications
・・・⑩
R ≧
Vcc – VOLM
VOHM
IOHM
IOLM
・・・⑦
Technical Note
2010.07 - Rev.A
・・・⑧
Datasheet pdf - http://www.DataSheet4U.net/