Datasheet

Section 5 Clock Pulse Generators
Rev. 6.00 Mar. 24, 2006 Page 78 of 412
REJ09B0142-0600
5.1 System Clock Generator
Clock pulses can be supplied to the system clock divider either by connecting a crystal or ceramic
resonator, or by providing external clock input. Figure 5.2 shows a block diagram of the system
clock generator.
LPM
LPM: Low-power mode (standby mode, subactive mode, subsleep mode)
2
1
OSC
OSC
Figure 5.2 Block Diagram of System Clock Generator
5.1.1 Connecting Crystal Resonator
Figure 5.3 shows a typical method of connecting a crystal resonator. An AT-cut parallel-resonance
crystal resonator should be used. Figure 5.4 shows the equivalent circuit of a crystal resonator. A
resonator having the characteristics given in table 5.1 should be used.
1
2
C
1
C
2
OSC
OSC
C
1
= C
2
= 12 pF ±20%
Note: Capacitances are reference values.
Figure 5.3 Typical Connection to Crystal Resonator
C
S
C
0
R
S
OSC
1
OSC
2
L
S
Figure 5.4 Equivalent Circuit of Crystal Resonator