UPD78F9177 Datasheet, PDF (29/56 Pages) NEC – 8-BIT SINGLE-CHIP MICROCONTROLLER

µPD78F9177, 78F9177Y
Subsystem Clock Oscillator Characteristics (TA = −40 to +85 °C, VDD = 1.8 to 5.5 V)
Resonator Recommended Circuit
Parameter
Crystal
resonator
VPP XT1 XT2
R
Note 1
Oscillation frequency (fXT)
Conditions
C3 C4
Note 2
Oscillation stabilization time
VDD = 4.5 to 5.5 V
External
clock
Note 1
XT1
XT2
XT1 input frequency (fXT)
MIN. TYP. MAX. Unit
32 32.768 35 kHz
1.2
2
s
10
s
32
35 kHz
XT1 input high-/low-level width
(tXTH, tXTL)
14.3
15.6 µs
Notes 1. Indicates only oscillator characteristics. Refer AC Characteristics for instruction execution time.
2. Time required to stabilize oscillation after reset or STOP mode release.
Cautions 1. When using the subsystem 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 VSS0.
• 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 current
consumption, and is more prone to malfunction due to noise than the main system clock
oscillator. Particular care is therefore required with the wiring method when the subsystem
clock is used.
Remark For the resonator selection and oscillator constant, customers are requested to either evaluate the
oscillation themselves or apply to the resonator manufacturer for evaluation.
Data Sheet U14022EJ1V0DS00
29