SH7020 Datasheet, PDF (108/509 Pages) Renesas Technology Corp – SuperH™ RISC engine

C_L1 = C_L2 = IC–22 pF
C_L1
EXTAL
Rd
C_L2
XTAL
Figure 7.2 Connection of the Crystal Resonator (Example)
Table 7.1 Damping Resistance
Frequency [MHz] 2
4
8
12
16
20
Rd [Ω]
1k
500
200
0
0
0
Crystal Resonator: Figure 7.3 shows an equivalent circuit of the crystal resonator. Use a crystal
resonator with the characteristics listed in table 7.2.
XTAL
L
C_L
Rs
C₀
EXTAL
Figure 7.3 Crystal Resonator Equivalent Circuit
Table 7.2 Crystal Resonator Parameters
Frequency (MHz)
Parameter 2
4
8
12
16
20
Rs max [Ω] 500
120
80
60
50
40
Co max [pF] 7
7
7
7
7
7
Value to be determined (TBD)
7.2.2 External Clock Input
An external clock signal can be input at the EXTAL pin as shown in figure 7.6. The XTAL pin
should be left open. The frequency must be equal to the system clock (CK) frequency. The
specifications for the waveform of the external clock input are given below. Make the external
clock frequency the same as the system clock (CK).
90 RENESAS