Figure 11.5 Example Of Crystal Oscillator Circuit Connection - Hitachi SH7751 Hardware Manual

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VDD-RTC
Noise filter
R
RTC
3.3 V
Notes: 1. Select either the C
requirements such as the adjustment range, degree of stability, etc.
2. Built-in resistance value R
3. C
and C
in
out
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 C
(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 Oscillator Circuit Connection

Rev. 3.0, 04/02, page 286 of 1064
VSS-RTC
C
RTC
or C
side for the frequency adjustment variable capacitor according to
in
out
(typ. value) = 10 MΩ, R
f
values include floating capacitance due to the wiring. Take care when using a solid-
SH7751
Series
R
f
EXTAL2
C
in
(typ. value) = 400 kΩ
D
and C
as close as possible to the chip.
in
out
R
D
XTAL2
XTAL
C
out

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