BU9832GUL-W_10 Datasheet, PDF (13/19 Pages) Rohm – WL-CSP EEPROM family SPI BUS

BU9832GUL-W
Technical Note
●High speed operation
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 V_OL,
I_OL from V_IL characteristics of this IC.
○Pull up resistance
Microcontroller IOLM
RPU
VOLM
EEPROM
VILE
“L” output
“L” input
Fig.49 Pull up resistance
R_PU≥
V_OLM≤
V_CC-V_OLM
I_OLM
V_ILE
･･･①
･･･②
Example) When Vcc=5V, V_ILM=1.5V, V_OLM=0.4V, I_OLM=2mA,
from the equation ①,
R_PU≥
∴R_PU≥
5-0.4
2×10^-3
2.3[kΩ]
With the value of R_PU to satisfy the above equation, V_OLM becomes
0.4V or higher, and with V_ILE (=1.5V), the equation ② is also satisfied.
・V_ILM :EEPROM V_IH specifications
・V_OLM :Microcontroller V_OL specifications
・I_OLM :Microcontroller I_OL specifications
And, in order to prevent malfunction, mistake write at power ON/OFF, be sure to make CS pull up.
○Pull down resistance
VOHM
IOHM
EEPROM
VIHE
Fig.50 Pull down resistance
R_PD≥
V_OHM≥
V_OHM
I_OHM
V_IHE
･･･③
･･･④
Example) When V_CC=5V, V_OHM=V_CC-0.5V, I_OHM=0.4mA,
V_IHM=V_CC×0.7V, from the equation③,
R_PD≥
5-0.5
0.4×10^-3
∴R_PU≥
11.3[kΩ]
Further, by amplitude VIHE, VILE of signal input to EEPROM, operation speed changes. By inputting signal of amplitude
of VCC / GND level to input,
/ 0.2Vcc is input, operation
more stable high speed
speed becomes slow.
operations
ж1
can
be
realized.
On
the
contrary,
when
amplitude
of
0.8V_CC
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 V_CC / GND level.
(^ж1 At this moment, operating timing guaranteed value is guaranteed.)
tPD_VIL characteristics
80
Spe c
70
60
50
40
30
20
10
0
0
Vcc=2.5V
Ta=25℃
VIH=Vcc
CL=100pF
0.2
0.4
0.6
0.8
1
VIL[V]
Fig.51 V_IL dependency of data output delay time
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13/18
2010.10 - Rev.A