UPD784044 Datasheet, PDF (58/90 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784044(A), 784046(A)
(1) Electrical specifications of µPD784044(A), 784046(A) (2/6)
Oscillation Circuit Characteristics (TA = –40 to +85 ˚C, VDD = 4.5 to 5.5 V, VSS = 0 V)
Resonator
Ceramic resonator or
crystal resonator
Recommended Circuit
VSS
X1
X2
Item
Oscillation frequency (fXX)
MIN.
8
MAX.
25
Unit
MHz
C1
C2
External clock
X1 input frequency (fX)
8
25
MHz
X1
X2
X1 input rise, fall time
Open^Note
0
5
ns
HCMOS inverter
X1 input high-, low-level
20
105
ns
width
Note When the EXTC bit of the oscillation stabilization time specification register (OSTS) = 0. Input the reverse
phase clock of the pin X1 to the pin X2 when the EXTC bit = 1.
Caution When using a system clock oscillation circuit, wire the portion enclosed by the dotted line in
the diagram above as follows to prevent adverse influence from wiring capacitance:
• Keep the wiring length as short as possible.
• Do not cross the wiring with any other signal lines. Do not route the wiring in the vicinity
of a line through which a high alternating current flows.
• Always keep the ground potential for the capacitor in the oscillation circuit at the same
potential as VSS. Do not ground the capacitor to a ground pattern through which a high current
flows.
• Do not extract any signal from the oscillation circuit.
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