SH7080_09 Datasheet, PDF (142/1622 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family

Section 4 Clock Pulse Generator (CPG)
4.6 Oscillator
Clock pulses can be supplied from a connected crystal resonator or an external clock.
4.6.1 Connecting Crystal Resonator
A crystal resonator can be connected as shown in figure 4.2. Use the damping resistance (Rd)
listed in table 4.6. Use a crystal resonator that has a resonance frequency of 5 to 12.5 MHz. It is
recommended to consult the crystal resonator manufacturer concerning the compatibility of the
crystal resonator and the LSI.
C_L1
EXTAL
XTAL
R_d
C_L2
C_L1 = C_L2 = 18 to 22 pF (Reference values)
Figure 4.2 Connection of Crystal Resonator (Example)
Table 4.6 Damping Resistance Values (Reference Values)
Frequency (MHz)
5
8
10
12.5
Rd (Ω)(Reference values)
500
200
0
0
Figure 4.3 shows an equivalent circuit of the crystal resonator. Use a crystal resonator with the
characteristics listed in table 4.7.
XTAL
C_L
L
Rs
EXTAL
C₀
Figure 4.3 Crystal Resonator Equivalent Circuit
Table 4.7 Crystal Resonator Characteristics
Frequency (MHz)
5
8
10
12.5
Rs Max. (Ω) (Reference values) 120
80
60
50
C0 Max. (pF) (Reference values) 7
7
7
7
Rev. 4.00 Dec. 15, 2009 Page 82 of 1558
REJ09B0181-0400