UPD784224 Datasheet, PDF (64/92 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784224, 784225, 784224Y, 784225Y
Subsystem Clock Oscillator Characteristics (TA = −40°C to +85°C, VDD = VDD0 = VDD1)
Resonator Recommended Circuit
Parameter
Crystal
resonator
VSS XT2 XT1
Oscillation frequency (fXT)
Oscillation stabilization
time^Note
Conditions
4.5 V ≤ VDD ≤ 5.5 V
1.8 V ≤ VDD < 4.5 V
MIN. TYP. MAX. Unit
32 32.768 35 kHz
1.2
2
s
10
External
clock
XT2
XT1
µ PD74HCU04
XT1 input frequency (fXT)
XT1 input high-/low-level
width (tXTH, tXTL)
32
35 kHz
14.3
15.6 µs
Note Time required to stabilize oscillation after applying supply voltage (VDD).
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 VSS.
• 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.
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Data Sheet U12376EJ1V0DS00