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CHAPTER 1 OVERVIEW
1.8 Handling of Devices
This section provides notes on using devices.
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Device Handling
❍
Latchup prevention
If voltage higher than Vcc or lower than Vss is applied to a CMOS IC input or output pin or if
voltage exceeding the rating is applied between Vcc and Vss, latchup may be caused. Latchup
rapidly increases supply current and may cause thermal damage to the device. To prevent
such damage, do not to let voltage exceed the maximum rated voltage.
Also, do not to let the analog power supply exceed the digital power supply.
❍
Treatment of unused input pin
Leaving an unused input pin open may cause a malfunction. To avoid this malfunction, pull it up
or push it down.
❍
Input of external reset signal
To ensure that the device is completely reset when the L level is input to the RSTX pin, the L
level input to the RSTX pin must continue for at least five machine cycles.
❍
Note on using an external clock
When an external clock is used, use the X0 pin unless otherwise specified and supply a
negative-phase clock to the X1 pin simultaneously. Do not use STOP mode (oscillation stop
mode) for this operation because the X1 pin is disabled when H is output at STOP.
At 12.5 MHz, an external clock can be used by supplying it to only the X0 pin.
Figures 1.8.1 and 1.8.2 show examples of using an external clock.
Figure 1.8-1 Example of Using an External Clock (Normal Method)
Note:
STOP mode (oscillation stop mode) cannot be used.
X0
X1
MB91F109