HD6417706 Datasheet, PDF (390/709 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer Super RISC engine Family/SH7700 Series

13.4.5 Crystal Oscillator Circuit
Crystal oscillator circuit constants (recommended values) are shown in table 13.2, and the RTC
crystal oscillator circuit in figure 13.5.
Table 13.2 Recommended Oscillator Circuit Constants (Recommended Values)
fosc
32.768 kHz
Cin
10 to 22 pF
Cout
10 to 22 pF
SH7706
Rf
EXTAL2
XTAL
Cin
RD
XTAL2
Cout
Notes:
1. Select either the Cin or Cout side for frequency adjustment variable capacitor according to requirements
such as frequency range, degree of stability, etc.
2. Built-in resistance value Rf (Typ value) = 10 MΩ, RD (Typ value) = 400 kΩ
3. Cin and Cout values include floating capacitance due to the wiring. Take care when using a ground
plane.
4. The crystal oscillation settling time depends on the mounted circuit constants, floating capacitance, etc.,
and should be decided after consultation with the crystal resonator manufacturer.
5. Place the crystal resonator and load capacitors Cin and Cout as close as possible to the chip.
(Correct oscillation may not be possible if there is externally induced noise in the EXTAL2 and XTAL2
pins.)
6. Ensure that the crystal resonator connection pin (EXTAL2, XTAL2) wiring is routed as far away as
possible from other power lines (except GND) and signal lines.
Figure 13.5 Example of Crystal Oscillator Circuit Connection
Rev. 4.00, 03/04, page 344 of 660