BU9833GUL-W_10 Datasheet, PDF (16/19 Pages) Rohm – WL-CSP EEPROM family I2C BUS

BU9833GUL-W
Technical Note
●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, function of POR circuit and LVCC circuit are equipped. To assure the action,
observe the following conditions 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
tOFF
Vbot
0
Fig. 55 Rise waveform diagram
Recommended conditions of t_R, t_OFF, Vbot
t_R
t_OFF
10ms or below
10ms or higher
100ms or below 10ms or higher
Vbot
0.3V or below
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 condition 1 cannot be observed. When SDA becomes “L” at power on.
→ Control SCL and SDA as shown below, to make SCL and, “H” and “H”.
VCC
SCL
tLOW
SDA
After Vcc becomes stable
After Vcc becomes stable
tDH tSU:DAT
tSU:DAT
Fig.56 When SCL =”H” and SDA = “L”
Fig.57 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 (P10).
c) In the case when the above conditions 1 and 2 cannot be observed.
→ Carry out a), and then carry out b).
●Low voltage malfunction prevention function
LVCC circuit prevents data rewrite action at low power, and prevents wrong write. At LVCC voltage (Typ. = 1.2V) or below, it
prevent data rewrite.
●Vcc noise countermeasures
○Bypass capacitor
When noise or surge gets in the power source line, malfunction may occur, therefore, for removing tese, it is
recommended to attach a by pass capacitor (0.1μF) between IC Vcc and GND. At that moment , attach it as close to IC
as possible.
And, it is also recommended to attach a bypass capacitor between board Vcc and GND.
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16/18
2010.10 - Rev.A