BU9891GUL-W_12 Datasheet, PDF (18/26 Pages) Rohm – WLCSP EEPROM

BU9891GUL-W (4Kbit)
Datasheet
○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
(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.
Microcontroller
EEPROM
Conditions
DI/O PORT
DI
VOHM ≦ VIHE
VOHM ≦ IOHM×R + VOLE
“H” output VOHM
At this moment, if VOLE=0V,
IOHM
R
DO
VOLE
VOHM ≦ IOHM×R
VOHM
∴
R≧
・・・⑦
IOHM
“L” output
Figure 51. Circuit at DI, DO direct connection
(Microcontroller DI/O “H” output, EEPROM “L” output)
・VIHE
・VOLE
・VOHM
・IOHM
: EEPROM VIH specifications
: EEPROM VOL specifications
: Microcontroller VOH specifications
: Microcontroller IOH specifications
(2) DO status READY output timing
(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.
Microcontroller
DI/O PORT
“L” output
VOLM
IOHM
EEPROM
DI
R
DO
Conditions
VOLM ≧ VILE
VOLM ≧ VOHE – IOLM×R
As this moment, VOHE=Vcc
VOLM ≧ Vcc – IOLM×R
Vcc – VOLM
∴
R≧
IOLM
・・・⑧
VOHE
“H” output
・VILE
・VOHE
・VOLM
・IOLM
Figure 52. Circuit at DI, DO direct connection
(Microcontroller DI/O “L” output, EEPROM “H” output)
: EEPROM VIL specifications
: EEPROM VOH specifications
: Microcontroller VOL specifications
: Microcontroller IOL specifications
Example) When Vcc=5V, VOHM=5V, IOHM=0.4mA, VOLM=5V, IOLM=0.4mA,
From the equation ⑦,
VOHM
R≧
IOHM
5
R≧
0.4×10^-3
∴ R ≧ 12.5 [kΩ] ・・・⑨
From the equation⑧,
Vcc – VOLM
R≧
IOLM
5 – 0.4
R≧
2.1×10^-3
∴ R ≧ 2.2 [kΩ] ・・・⑩
Therefore, from the equations ⑨ and ⑩,
∴ R ≧ 12.5 [kΩ]
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TSZ22111・15・001
18/22
TSZ02201-0R2R0G100440-1-2
3.SEP.2012 Rev.001