Product data

HD404818 Series
37
Internal Oscillator Circuit
Figure 20 shows the block diagram of the internal oscillator circuit. A ceramic oscillator can be connected
to OSC
1
and OSC
2
. A 32.768-kHz crystal oscillator can be connected to X1 and X2. External clock
operation is available for the system oscillator.
f
OSC
X2
X1
Subsystem
oscillator
1/4
divider
circuit
1/8
divider
circuit
Mode
control
circuit
Timing
generator
circuit
OSC
f
X
cyc
f
SUB
f
Timing
generator
circuit
System clock
(ø
CPU
)
System clock
(ø
PER
)
Timer-base
clock (ø
CLK
)
OSC
System
oscillator
1
2
Figure 20 Internal Oscillator Circuit
D
0
RESET
OSC
2
OSC
1
V
CC
NUMG
COMP
1
/D
13
TEST
X1
X2
GND
SCK/R0
0
GND
Figure 21 Layout of Crystal and Ceramic Oscillators