BU9897GUL-W Datasheet, PDF (3/5 Pages) Rohm – Silicon Monolithic Integrated Circuit

3/4
◇NOTES FOR POWER SUPPLY
Vcc rises through the low voltage region in which internal circuit of IC and the controller are unstable, so that device may not work
properly due to an incomplete reset of internal circuit. To prevent this, the device has the feature of P.O.R. and LVCC. In the case of
power up, keep the following conditions to ensure functions of P.O.R. and LVCC.
1. It is necessary to be "SDA='H'" and "SCL='L' or 'H'".
2. Follow the recommended conditions of tR, tOFF, Vbot for the function of P.O.R. during power up.
tR
◇RECOMMENDED CONDITIONS OF tR, tOFF, Vbot
Vcc
tOFF
Vbot
0
Fig.-2 Vcc RISING WAVEFORM
3. Prevent SDA and SCL from being "High-Z".
In case that condition 1. and/or 2. cannot be met,
take following actions.
Vcc
tLOW
A） Unable to keep condition 1.
SCL
( SDA is "LOW" during power up.)
→Control SDA ,SCL to be "HIGH" as Fig.-3(a),
SDA
3(b).
B）Unable to keep condition 2.
→After power becomes stable, execute
After Vcc becomes stable
tDH tSU:DAT
Fig.-3（a） SCL='H' and SDA='L'
C）Unable to keep both conditions 1 and 2.
→Follow the instruction A first, then the instruction B.
After Vcc becomes stable
tSU:DAT
Fig.-3（b） SCL='L' and SDA='L'
◇CAUTIONS ON USE
(1) Absolute maximum ratings
If the absolute maximum ratings such as impressed voltage and action temperature range and so forth are exceeded, LSI may
be destructed. Do not impress voltage and temperature exceeding the absolute maximum ratings. In the case of fear exceeding
the absolute maximum ratings, take physical safety countermeasures such as fuses, and see to it that conditions exceeding
the absolute maximum ratings should not be impressed to LSI.
(2) GND electric potential
Set the voltage of GND terminal lowest at any action condition. Make sure that each terminal voltage is not lower than that of
GND terminal.
(3) Thermal design
In consideration of permissible loss in actual use condition, carry out heat design with sufficient margin.
(4) Terminal to terminal shortcircuit and wrong packaging
When to package LSI onto a board, pay sufficient attention to LSI direction and displacement. Wrong packaging may destruct
LSI. And in the case of shortcircuit between LSI terminals and terminals and power source, terminal and GND owing to
foreign matter, LSI may be destructed.
(5) Use in a strong electromagnetic field may cause malfunction, therefore, evaluated design sufficiently.
REV. B