MB89202 Series
10
■
HANDLING DEVICES
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 section “
■
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.
Treatment of Unused Input Pins
Leaving unused input terminals open may lead to permanent damage due to malfunction and latchup; pull up
or pull down the terminals through the resistors of 2 k
or more.
Make the unused I/O terminal in a state of output and leave it open or if it is in an input state, handle it with the
same procedure as the input terminals.
Treatment of N.C. Pins
Be sure to leave (internally connected) N.C. pins open.
Power Supply Voltage Fluctuations
Although V
CC
power supply voltage is assured to operate within the rated range, 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 fluctuations (P-P
value) will be less than 10
%
of the standard V
CC
value at the commercial frequency (50 Hz 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
When an external clock is used, oscillation stabilization time is required even for power-on reset (optional) and
wake-up from stop mode.
About the Wild Register Function
No wild register can be debugged on the MB89V201. For the operation check, test the MB89F202 installed on
a target system.
Program Execution in RAM
When the MB89V201 is used, no program can be executed in RAM.
Note to Noise in the External Reset Pin (RST)
If the reset pulse applied to the external reset pin (RST) does not meet the specifications, it may cause malfunc-
tions. Use caution so that the reset pulse less than the specifications will not be fed to the external reset pin (RST).
External pullup for the External Reset Pin (RST) of MB89F202
Internal pullup control for RST pin is not available for MB89F202. To ensure proper external reset control in
MB89F202, an external pullup (recommend 100 k
) for RST pin must be required.
(Continued)