BU99901GUZ-W_10 Datasheet, PDF (14/17 Pages) Rohm – WL-CSP EEPROM family I2C BUS

BU99901GUZ-W
●I²C BUS input / output circuit
○Input (SCL, SDA)
○Input/Output (SDA)
Fig.49 Input pin circuit diagram
VDD
Technical Note
Fig.50 Input /output pin circuit diagram
●Notes on power ON
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.
tR
VCC
0
Fig.51
tOFF
Vbot
Rise waveform diagram
Recommended conditions of tR,tOFF,Vbot
tR
tOFF
Vbot
10ms or below 10ms or longer 0.3V or below
100ms or below 10ms or longer 0.2V or below
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.
a) In the case when the above conditions 1 cannot be observed. When SDA becomes 'L' at power on .
→Control SCL and SDA as shown below, to make SCL and SDA, 'H' and 'H'.
VCC
SCL
tLOW
SDA
A ft er V cc bec omes st able
tDH tSU:DAT
Fig.52 When SCL='H' and SDA='L'
Af t er Vcc becom es stab le
tSU:DAT
Fig.53 When SCL='H' and SDA='L'
b) In the case when the above condition 2 cannot be observed.
→After power source becomes stable, execute software reset(P11).
c) In the case when the above conditions 1 and 2 cannot be observed.
→Carry out a), and then carry out b).
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14/16
2010.09 - Rev.A