CHAPTER 20 ELECTRICAL SPECIFICATIONS
User’s Manual U15109EJ3V0UD
687
(2) Subclock oscillator (T
A
= –40 to +85°C)
(a) Connection of crystal resonator
XT1
XT2
Parameter
Symbol
Conditions
MIN.
TYP.
MAX.
Unit
Oscillation frequency
f
XT
32.768
kHz
Oscillation stabilization time
–
When reset is released
10
s
Cautions 1. Subclock oscillator operates on the output voltage of the on-chip regulator.
External clock input is prohibited.
2. When using the subclock oscillator, wire as follows in the area enclosed by the broken lines
in the above figure 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 V
SS
.
••••
Do not ground the capacitor to a ground pattern through which a high current flows.
••••
Do not fetch signals from the oscillator.
3. For the resonator selection and oscillator constant, customers are requested to either
evaluate the oscillation themselves or apply to the resonator manufacturer for evaluation.