HD404618 Datasheet, PDF (37/91 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404618 Series
Internal Oscillator Circuit
Figure 21 shows a block diagram of the internal oscillator circuit. A ceramic oscillator can be connected to
OSC₁ and OSC₂, and a 32.768-kHz crystal oscillator can be connected to X1 and X2. The system oscillator
can also be operated by an external clock.
$&',-^OSC1
OSC₂
X1
X2
System ^{f OSC}
oscillator
Divider
(1/4)
Subsystem ^f X
oscillator
Divider
(1/8)
Timing
f _cyc
generator
Mode
control
circuit
Timing ^f SUB
generator
Figure 21 Internal Oscillator Circuit
D₀
RESET
OSC₂
OSC₁
V_CC
VT_ref
GND
COMP₁/D₁₃
TEST
X1
X2
GND
SCK/R0₀
Figure 22 Layout of Crystal and Ceramic Oscillators
System clock
(ø _CPU )
System clock
(ø _PER )
Timer-base
clock (ø _CLK )
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