4.3
Subclock Generator
1. Connecting a 32.768-kHz/38.4 kHz crystal oscillator
Clock pulses can be supplied to the subclock divider by connecting a 32.768-kHz/38.4 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.
C1
X1
X2
C1 = C2 = 15 pF (typ.)
C2
Figure 4-7 Typical Connection to 32.768-kHz/38.4 kHz Crystal Oscillator (Subclock)
Figure 4-8 shows the equivalent circuit of the 32.768-kHz/38.4 kHz crystal oscillator.
CS
LS
RS
X1
X2
C0
C0 = 1.5 pF typ
RS = 14 kΩ typ
fW = 32.768 kHz/38.4kHz
Figure 4-8 Equivalent Circuit of 32.768-kHz/38.4 kHz Crystal Oscillator
92
ETC [ ETC ]
