SH7280 Datasheet, PDF (118/1726 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine family

Section 4 Clock Pulse Generator (CPG)
4.6 Oscillator
The source of click supply can be selected from a connected crystal resonator or an external clock
input through a pin.
4.6.1 Connecting Crystal Resonator
A crystal resonator can be connected as shown in figure 4.2. Use the damping resistance (R_d)
shown in table 4.5. Use a crystal resonator that has a resonance frequency of 10 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 value)
Figure 4.2 Example of Crystal Resonator Connection
Table 4.5 Damping Resistance Values (Reference Values)
Frequency (MHz)
10
12.5
R
d
(Ω)
(reference
value)
0
0
Figure 4.3 shows an equivalent circuit of the crystal resonator. Use a crystal resonator with the
characteristics shown in table 4.6.
XTAL
C_L
L
R_S
EXTAL
C₀
Figure 4.3 Crystal Resonator Equivalent Circuit
Rev. 1.00 Jun. 26, 2008 Page 88 of 1692
REJ09B0393-0100