SH7751 Datasheet, PDF (412/1224 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

11. Realtime Clock (RTC)
VDD-RTC
This LSI
Rf
VSS-RTC
EXTAL2
RD
XTAL2
Noise filter
CRTC
RRTC
3.3 V
XTAL
C_in
Cout
Notes: 1. Select either the Cin or Cout side for the frequency adjustment variable capacitor according to
requirements such as the adjustment range, degree of stability, etc.
2. Built-in resistance value Rf (typ. value) = 10 MΩ, RD (typ. value) = 400 kΩ
3. Cin and C_out values include floating capacitance due to the wiring. Take care when using a solid-
earth board.
4. The crystal oscillation stabilization 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 and XTAL2) wiring is routed as far away
as possible from other power lines (except GND) and signal lines.
7. Insert a noise filter in the RTC power supply.
Figure 11.5 Example of Crystal Oscillation Circuit Connection
Rev.4.00 Oct. 10, 2008 Page 314 of 1122
REJ09B0370-0400