NEC 78K0 User Manual page 446

CHAPTER 27 ELECTRICAL SPECIFICATIONS ((A2) GRADE PRODUCTS)
X1 Oscillator Characteristics
= −40 to +125°C, 3.3 V ≤ V
(T
A
Resonator Recommended Circuit
Ceramic
V
X1
SS
resonator
C1
Crystal
V
X1
SS
resonator
C1
External clock
X1
Note Indicates only oscillator characteristics. Refer to AC Characteristics for instruction execution time.
Cautions 1. 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 V
• Do not ground the capacitor to a ground pattern through which a high current flows.
• Do not fetch signals from the oscillator.
2. Since the CPU is started by the Ring-OSC after reset is released, check the oscillation
stabilization time of the X1 input clock using the oscillation stabilization time status register
(OSTC). 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.
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.
446
≤ 5.5 V, 3.3 V ≤ AV
= EV
DD DD
Parameter
Oscillation frequency
X2
Note
(f )
XP
C2
Oscillation frequency
X2
Note
(f )
XP
C2
X1 input frequency
X2
Note
(f )
XP
X1 input high-/low-
level width (t , t
XPH XPL
User's Manual U16227EJ2V0UD
≤ V
, V = EV
REF DD SS SS
Conditions
4.0 V ≤ V
< 5.5 V
DD
3.3 V ≤ V
< 4.0 V
DD
4.0 V ≤ V
< 5.5 V
DD
3.3 V ≤ V
< 4.0 V
DD
4.0 V ≤ V
< 5.5 V
DD
3.3 V ≤ V
< 4.0 V
DD
4.0 V ≤ V
< 5.5 V
DD
)
3.3 V ≤ V
< 4.0 V
DD
= AV = 0 V)
SS
MIN. TYP. MAX.
2.0 8.38
2.0 5.0
2.0 8.38
2.0 5.0
2.0 8.38
2.0 5.0
56 500
96 500
.
SS
Unit
MHz
MHz
MHz
ns