Datasheet

Section 4 Clock Pulse Generators
Rev. 8.00 Mar. 09, 2010 Page 111 of 658
REJ09B0042-0800
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 = 7 pF (typ.)
1 2
Frequency
32.768 kHz*
Crystal oscillator
EPSON TOYOCOM.
Products Name
C-001R
Motion Resistance
35 kΩ max
Notes: Circuit constants should be detemined in consultation with the
resonator manufacture.
* H8/38124 Group only.
C = C = 15 pF (typ.)
1 2
Frequency
38.4 kHz
32.768 kHz
Crystal oscillator
Seiko Instruments 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
LR
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