APPENDIX B LIST OF CAUTIONS
User’s Manual U17854EJ9V0UD
852
(28/33)
Chapter
Cl
assi
fi
cati
on
Function
Details of
Function
Cautions
Page
The 78K0R/KE3 has an on-chip debug function, which is provided for development
and evaluation. Do not use the on-chip debug function in products designated for
mass production, because the guaranteed number of rewritable times of the flash
memory may be exceeded when this function is used, and product reliability therefore
cannot be guaranteed. NEC Electronics is not liable for problems occurring when the
on-chip debug function is used.
p.705
pp.705,
Absolute
maximum ratings
Product quality may suffer if the absolute maximum rating is exceeded even
momentarily for any parameter.
That is, the absolute maximum ratings are rated
values at which the product is on the verge of suffering physical damage, and
therefore the product must be used under conditions that ensure that the absolute
maximum ratings are not exceeded.
706
p.707
When using the X1 oscillator, wire as follows in the area enclosed by the broken lines
in the above figures to avoid an adverse effect from wiring capacitance.
Keep the wiring length as short as possible.
Do not cross the wiring with the other signal lines.
Do not route the wiring near a signal line through which a high fluctuating current
flows.
Always make the ground point of the oscillator capacitor the same potential as VSS.
Do not ground the capacitor to a ground pattern through which a high current flows.
Do not fetch signals from the oscillator.
p.707
X1 oscillator
characteristics
Since the CPU is started by the internal high-speed oscillation clock after a reset
release, check the X1 clock oscillation stabilization time using the oscillation
stabilization time counter status register (OSTC) by the user.
Determine the
oscillation stabilization time of the OSTC register and oscillation stabilization time
select register (OSTS) after sufficiently evaluating the oscillation stabilization time
with the resonator to be used.
p.709
When using the XT1 oscillator, wire as follows in the area enclosed by the broken
lines in the above figures to avoid an adverse effect from wiring capacitance.
Keep the wiring length as short as possible.
Do not cross the wiring with the other signal lines.
Do not route the wiring near a signal line through which a high fluctuating current
flows.
Always make the ground point of the oscillator capacitor the same potential as VSS.
Do not ground the capacitor to a ground pattern through which a high current flows.
Do not fetch signals from the oscillator.
p.709
XT1 oscillator
characteristics
The XT1 oscillator is designed as a low-amplitude circuit for reducing power
consumption, and is more prone to malfunction due to noise than the X1 oscillator.
Particular care is therefore required with the wiring method when the XT1 clock is
used.
pp.710
to 713
Chapter
2
7
Hard
Electrical
specifications
(standard
products)
Recommended
oscillator
constants
The oscillator constants shown above are reference values based on evaluation in a
specific environment by the resonator manufacturer. If it is necessary to optimize the
oscillator characteristics in the actual application, apply to the resonator manufacturer
for evaluation on the implementation circuit.
When doing so, check the conditions for using the AMPH bit, RMC register, and
whether to enter or exit the STOP mode.
The oscillation voltage and oscillation frequency only indicate the oscillator
characteristic.
Use the 78K0R/KE3 so that the internal operation conditions are
within the specifications of the DC and AC characteristics.