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4.3
Subclock Generator
1. Connecting a 76.8-kHz/160-kHz crystal oscillator
Clock pulses can be supplied to the subclock divider by connecting a 76.8-kHz/160-kHz crystal
oscillator, as shown in figure 4-7. Follow the same precautions as noted under 3. notes on board
design for the system clock in 4.2.
Figure 4-7 Typical Connection to 76.8-kHz/160-kHz Crystal Oscillator (Subclock)
Figure 4-8 shows the equivalent circuit of the 76.8-kHz/160-kHz crystal oscillator.
DX
1
Figure 4-8 Equivalent Circuit of 76.8-kHz/160-kHz Crystal Oscillator
2. Pin connection when not using subclock
When the subclock is not used, connect pin DX
figure 4-9.
Figure 4-9 Pin Connection when not Using Subclock
C
1
DX
1
DX
2
C
2
C
S
L
S
DX
1
DX
2
C = C
= 12.5 pF (typ.)
1
2
R
S
C
0
f
= 76.8 kHz/160 kHz
W
to GND and leave pin DX
1
GND
Open
DX
2
open, as shown in
2
89
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