Datasheet

Section 4 Clock Pulse Generators
Rev. 6.00 Aug 04, 2006 page 122 of 680
REJ09B0145-0600
The circuit parameters are affected by the crystal or ceramic oscillator and floating
capacitance when designing the board. When using the oscillator, consult with the crystal
or ceramic oscillator manufacturer to determine the circuit parameters.
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 4.6. Follow the same precautions as noted under 3. notes on board
design for the system clock in section 4.2.
X
X
C
1
C
2
1
2
C = C = 15 pF (typ.)
12
Note: Circuit constants should be determined in consultation
with the resonator manufacturer.
32.768 kHz Nihon Denpa Kogyo MX73P
38.4 kHz VTC-200Seiko Instrument Inc.
Oscillation frequency Manufacturer Products Name
Figure 4.6 Typical Connection to 32.768 kHz/38.4 kHz Crystal Oscillator (Subclock)
Figure 4.7 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/38.4kHz
0
S
W
Ω
S
Figure 4.7 Equivalent Circuit of 32.768 kHz/38.4 kHz Crystal Oscillator