BU9829GUL-W_10 Datasheet, PDF (11/17 Pages) Rohm – WL-CSP EEPROM family SPI BUS

BU9829GUL-W
Technical Note
●EEPROM part
1. Hardware Connection of EEPROM
EEPROM may have malfunction owing to noise signal for input pin, and movement in the low voltage region at power
ON/OFF. These malfunctions may occur, especially at min voltage limit of EEPROM or below.
To avoid this, please note about hardware connection showed as follows.
1.1 Input Terminals
Input equivalent circuits of CSB, SCK and SI are showed Fig.47, 48.
Input terminal is connected between CMOS schmitt trigger input circuit and input protection circuit.
These pin are not pull up or pull down, therefore please don’t input Hi-Z in use. And please make CSB “HIGH” in the
low voltage region at power ON/OFF. If CSB is "LOW" at power ON/OFF, malfunction may occur. To make other input
terminals pull up or pull down is recommendable.
CSB
SCK, SI
ＳＯ
Fig.47 CSB terminals
equivalent circuit
Fig.48 SCK,SI terminals
equivalent circuit
Fig.49 SO terminals
equivalent circuit
1.2 Output Terminals
Output equivalent circuit of so is showed Fig.49. This output terminal is 3 states buffer.
The data is output from so at output timing by READ command, so is Hi-z except this timing. If EEPROM malfunction
occur by Hi-z input of the microcontroller port connected with so, please make so pull up or pull down. If it doesn’t
affected the microcontroller movement to make so open, it is no problem. Load capacity of so disturb high speed
movement of EEPROM. If this load capacity is 100pF or below, BU9829GUL-W can move in 2.5MHz
(Vcc1=1.6V~1.8V) or 5MHz (Vcc1=1.8V~3.6V)
1.3 Input pin pull up, pull down resistance
The design method of pull up/pull down resistance for input and output are as follows.
1.3.1 Pull up resistance Rpu of input terminals
Microcontroller
V_OLM ^IOLM
Rpu ^EEPROM
V_ILE
“L” output
“L” input
Rpu ≧
VOLM ≦
V_CC－V_OLM
I_OLM
VILE
…①
…②
Example) When Vcc=5V, VILE=1.5V, VOLM=0.4V, IOLM=2mA,
from the equation①,
Fig.50 Input terminal pull up resistance
・VILE : EEPROM VIL specifications
・VOLM : Microcontroller VOL specifications
・IOLM : Microcontroller IOL specifications
Rpu ≧
∴Rpu ≧
5－0.4
2×10^-3
2.3[kΩ]
With the value of Rpu to satisfy the above equation, VOLM
becomes 0.4V or below, and with VILE(=1.5V), the equation
② is also satisfied.
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11/16
2010.09 - Rev.A