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MB89890 Series
11
I
HANDLING DEVICES
1.
Preventing Latchup
Latchup may occur on CMOS ICs if voltage higher than V
CC
or lower than V
SS
is applied to input and output pins
other than medium- and high-voltage pins or if higher than the voltage which shows on “1. Absolute Maximum
Ratings” in “
I
ELECTRICAL CHARACTERISTICS” is applied between V
CC
and V
SS
.
When latchup occurs, power supply current increases rapidly and might thermally damage elements. When
using, take great care not to exceed the absolute maximum ratings.
Also take care to prevent the analog power supply (AV
CC
and AVR) and analog input from exceeding the digital
power supply (V
CC
) when the analog system power supply is turned on and off.
Treatment of Unused Input Pins
2.
Leaving unused input pins open could cause malfunctions. They should be connected to pull-up or pull-down
resistor.
Treatment of Power Supply Pins on Microcontrollers with A/D and D/A Converters
3.
Connect to be AV
CC
= DAVC = V
CC
and AV
SS
= AVR = V
SS
even if the A/D and D/A converters are not in use.
Treatment of N.C. Pins
4.
Be sure to leave (internally connected) N.C. pins open.
Power Supply Voltage Fluctuations
5.
Although operation is assured within the rated range of V
CC
power supply voltage, a rapid fluctuation of the
voltage could cause malfunctions, even if it occurs within the rated range. Stabilizing voltage supplied to the IC
is therefore important. As stabilization guidelines, it is recommended to control power so that V
CC
ripple fluctu-
ations (P-P value) will be less than 10% of the standard V
CC
value at the commercial frequency (50 to 60 Hz)
and the transient fluctuation rate will be less than 0.1 V/ms at the time of a momentary fluctuation such as when
power is switched.
Precautions when Using an External Clock
6.
When an external clock is used, oscillation stabilization time is required for even power-on reset (optional) and
release from stop mode.