Renesas H8/38024 Series, Hardware Manual

Page: 139 / 661

Rev. 6.00, 08/04, page 109 of 628
4.3 Subclock Generator
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 4.8. Follow the same precautions as noted under 3. notes on board
design for the system clock in section 4.2.
Note that only operation at 32.768 kHz is guaranteed on the H8/38124 Group.
X
X
C
1
C
2
1
2
C = C = 15 pF (typ.)
1 2
Frequency
38.4 kHz
32.768 kHz
Crystal oscillator
Seiko Instrument Inc.
Nihon Denpa Kogyo
Products Name
VTC-200
MX73P
Figure 4.8 Typical Connection to 32.768 kHz/38.4 kHz Crystal Oscillator (Subclock)
Figure 4.9 shows the equivalent circuit of the 32.768 kHz/38.4 kHz crystal oscillator.
C
S
C
0
L R
S
X
1
X
2
C = 1.5 pF typ
R = 14 k typ
f = 32.768 kHz/38.4 kHz
0
S
W
Ω
S
Figure 4.9 Equivalent Circuit of 32.768 kHz/38.4 kHz Crystal Oscillator