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CHAPTER 2 HANDLING DEVICE
2.1
Notes on Handling Devices
This section describes the precautions to be taken when handling the power supply
voltage and pins of the device.
I
Notes on Handling Devices
H
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- to high-voltage pins, or if voltage higher than ratings 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
, BV
CC
, CV
CC
, AVR, CVRH1, CVRH2,
and CVRL) and analog input from exceeding the digital power supply (V
CC)
when the analog
system power supply is turned on and off.
H
Treatment of Unused Input Pins
Leaving unused input pins open could cause malfunctions. They should be connected to a pull-
up or pull-down resistor.
H
Treatment of Power Supply Pins on Microcontroller with A/D and D/A Converters
Connect to be AV
CC
= BV
CC
= CV
CC
= V
CC
and AV
SS
= AVR = CV
SS
= CVRL = CVRH1 =
CVRH2 = V
SS
even if the A/D and D/A converters are not in use.
H
Treatment of Unused Input Pins
Be sure to leave (internally connected) N.C. pins open.
H
Power Supply Voltage Fluctuations
Although V
CC
power supply voltage is assured to operate within the rated range, a rapid
fluctuation of 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 fluctuations (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.
H
Precautions when Using an External Clock
Even when an external clock is used, oscillation stabilization time is required for power-on reset
and wake-up from stop mode.