NEC PD78F9488 - Manual (Page 344)

CHAPTER 22 ELECTRICAL SPECIFICATIONS ( µ PD789488, 78F9488, 789489, 78F9489)
344
User’s Manual U15331EJ4V1UD
Main System Clock Oscillator Characteristics (T
A
= –40 to +85 °C, V
DD
= 1.8 to 5.5 V)
Resonator Recommended Circuit Parameter Conditions MIN. TYP. MAX. Unit
Oscillation frequency (f
X
) Note 1 1.0 5.0 MHz Ceramic
resonator X2 X1 V
SS
C2 C1
Oscillation stabilization
time
Note 2
After V
DD
reaches
oscillation voltage
range MIN.
4 ms
Oscillation frequency(f
X
) Note 1 1.0 5.0 MHz
V
DD
= 4.5 to 5.5 V 10 ms
Crystal
resonator X2 X1 V
SS
C2 C1
Oscillation stabilization
time
Note 2
V
DD
= 1.8 to 5.5 V 30 ms
X1 input frequency (f
X
) Note 1 1.0 5.0 MHz
X1 X2
X1 input high-/low-level width
(t
XH
, t
XL
)
85 500 ns
X1 input frequency (f
X
) Note 1 V
DD
= 2.7 to 5.5 V 1.0 5.0 MHz
External
clock
X1 X2
OPEN
X1 input high-/low-level width
(t
XH
, t
XL
)
V
DD
= 2.7 to 5.5 V 85 500 ns
Notes 1. Indicates only oscillator characteristics. Refer to AC Characteristics for instruction execution time.
2. Time required to stabilize oscillation after reset or STOP mode release.
Cautions 1. When using the main system clock 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
SS
.
• Do not ground the capacitor to a ground pattern through which a high current flows.
• Do not fetch signals from the oscillator.
2. When the main system clock is stopped and the device is operating on the subsystem clock,
wait until the oscillation stabilization time has been secured by the program before switching
back to the main system clock.
Remark For the resonator selection and oscillator constant, customers are required to either evaluate the
oscillation themselves or apply to the resonator manufacturer for evaluation.