
55
μ
PD75236
Note
When using a main system clock and subsystem clock oscillator, wire the crosshatched section in
Figs. 4-17 and 4-18 as follows to prevent any effect of the wiring capacity.
Make the wiring as short as possible.
Do not allow wiring to intersect with other signal conductors. Do not allow wiring to be near a line
through which varying high current flows.
Set the oscillator capacitor grounding point to the same potential as that of V
SS
. Do not ground to a
ground pattern through which high current flows.
Do not fetch signals from the oscillator.
The subsystem clock oscillator has a low amplification factor to maintain low current consumption
and is more likely to malfunciton due to noise than the main system clock oscillator. Thus, take extra
care when using a subsystem clock.
(5)
System clock oscillator
The main system clock oscillator oscillates with a crystal resonator (with a standard frequency of 4.19
MHz) or a ceramic resonator connected to the X1 and X2 pins.
External clocks can be input to this oscillator.
Fig. 4-17 External Circuit of Main System Clock Oscillator
(a) Crystal/ceramic Oscillation
(b) External clock
X1
X2
X1
X2
External
Clock
Crystal or
Ceramic
Resonator
μ
PD75236
μ
PD75236
Note
The STOP mode cannot be set while an external clock is input because the X1 pin is short-circuited to
V
SS
in the STOP mode.
The subsystem clock oscillator oscillates with a crystal resonator (with a standard frequency of 32.768
kHz) connected to the XT1 and XT2 pins.
External clocks can be input to this oscillator.
Fig. 4-18 External Circuit of Subsystem Clock Oscillator
(a) Crystal oscillation
(b) External clock
External
Clock
XT1
XT2
XT1
XT2
32.768 kHz
μ
PD75236
μ
PD75236
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