NEC 78K0 User Manual page 447

8-bit single-chip microcontrollers
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CHAPTER 27 ELECTRICAL SPECIFICATIONS ((A2) GRADE PRODUCTS)
Ring-OSC Oscillator Characteristics
= −40 to +125°C, 3.3 V ≤ V
(T
A
Resonator
On-chip Ring-OSC oscillator
Subsystem Clock Oscillator Characteristics
= −40 to +125°C, 3.3 V ≤ V
(T
A
Resonator
Recommended Circuit
Crystal
V
XT2
SS
resonator
Rd
C4
XT2
External clock
Note Indicates only oscillator characteristics. Refer to AC Characteristics for instruction execution time.
Cautions 1. When using the subsystem clock 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
• Do not ground the capacitor to a ground pattern through which a high current flows.
• Do not fetch signals from the oscillator.
2. The subsystem clock 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 subsystem clock is used.
Remark For the resonator selection and oscillator constant, users are required to either evaluate the oscillation
themselves or apply to the resonator manufacturer for evaluation.
≤ 5.5 V, 3.3 V ≤ AV
= EV
DD
DD
Parameter
Oscillation frequency (f
)
R
≤ 5.5 V, 3.3 V ≤ AV
= EV
DD
DD
Parameter
Oscillation frequency
XT1
Note
(f
)
XT
C3
XT1
XT1 input frequency
Note
(f
)
XT
XT1 input high-/low-level
width (t
, t
)
XTH
XTL
User's Manual U16227EJ2V0UD
≤ V
, V
= EV
= AV
REF
DD
SS
SS
Conditions
≤ V
, V
= EV
= AV
REF
DD
SS
SS
Conditions
= 0 V)
SS
MIN.
TYP.
MAX.
Unit
120
240
495
kHz
= 0 V)
SS
MIN.
TYP.
MAX.
Unit
32
32.768
35
kHz
32
38.5
kHz
µ
12
15
s
.
SS
447

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