System Clock Oscillator; Main System Clock Oscillator; Subsystem Clock Oscillator - NEC 78014Y Series User Manual

7.4 System Clock Oscillator

7.4.1 Main system clock oscillator

The main system clock oscillator oscillates with a crystal resonator or a ceramic resonator (standard: 10.0 MHz)
connected to the X1 and X2 pins.
External clocks can be input to the main system clock oscillator. In this case, input a clock signal to the X1 pin
and its inverted signal to the X2 pin.
Figure 7-4 shows an external circuit of the main system clock oscillator.
(a) Crystal or ceramic oscillation
Caution The STOP mode cannot be set while an external clock is being input. This is because the X1 pin
is short-circuited to V

7.4.2 Subsystem clock oscillator

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The subsystem clock oscillator oscillates with a crystal resonator (standard: 32.768 kHz) connected to the XT1
and XT2 pins.
External clocks can be input to the subsystem clock oscillator. In this case, input a clock signal to the XT1 pin
and its inverted signal to the XT2 pin.
Figure 7-5 shows an external circuit of the subsystem clock oscillator.
(a) Crystal oscillation
Cautions are shown on the next page.
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CHAPTER 7 CLOCK GENERATOR
Figure 7-4. External Circuit of Main System Clock Oscillator
X2
X1
IC
Crystal or
Ceramic resonator
in the STOP mode.
SS
Figure 7-5. External Circuit of Subsystem Clock Oscillator
IC
XT2
32.768
kHz
XT1
(b) External clock
X2
External
X1
clock
PD74HCU04
(b) External clock
XT2
External
XT1
clock
PD74HCU04