BU9889GUL-W Rohm, BU9889GUL-W Datasheet - Page 15

• Manufacturer Part Number: BU9889GUL-W
• Description: WL-CSP EEPROM family I2C BUS
• Manufacturer: Rohm

● I2C BUS input / output circuit
●Notes on power ON
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BU9889GUL-W
www.rohm.com
○ Input (A2, SCL, WP)
○ Input/Output (SDA)
At power on, in IC internal circuit and set, Vcc rises through unstable low voltage area, and IC inside is not completely reset,
and malfunction may occur. To prevent this, functions of POR circuit and LVCC circuit are equipped. To assure the action,
observe the following condition at power on.
1. Set SDA = 'H' and SCL ='L' or 'H'
2. Start power source so as to satisfy the recommended conditions of tR, tOFF, and Vbot for operating POR circuit.
3. Set SDA and SCL so as not to become 'Hi-Z'.
When the above conditions 1 and 2 cannot be observed, take the following countermeasures.
V
CC
0
Fig.50 When SCL='H' and SDA='L'
Fig.49 Rise waveform diagram
SCL
SDA
V
CC
a) In the case when the above conditions 1 cannot be observed. When SDA becomes 'L' at power on .
b) In the case when the above condition 2 cannot be observed.
c) In the case when the above conditions 1 and 2 cannot be observed.
A ft er V cc bec omes st able
→ Control SCL and SDA as shown below, to make SCL and SDA, 'H' and 'H'.
→ After power source becomes stable, execute software reset(P11).
→ Carry out a), and then carry out b).
tOFF
Fig.47 Input pin circuit diagram
Fig.48 Input /output pin circuit diagram
tR
tDH
tLOW
Vbot
tSU:DAT
15/17
Recommended conditions of tR,tOFF,Vbot
Fig.51 When SCL='H' and SDA='L'
Af t er Vcc becom es stab le
100ms or below
10ms or below
tR
tSU:DAT
10ms or longer
10ms or longer
tOFF
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2010.01 - Rev.A
Technical Note
0.3V or below
0.2V or below
Vbot