Section 13 Realtime Clock (RTC)
Rev. 5.00 May 29, 2006 page 360 of 698
REJ09B0146-0500
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)
f
osc
C
in
C
out
32.768 kHz
10 to 22 pF
10 to 22 pF
SH7706
EXTAL2
XTAL2
XTAL
Cin
Cout
Rf
RD
Notes: 1. Select either the C
in
or C
out
side for frequency adjustment variable capacitor according to requirements
such as frequency range, degree of stability, etc.
2. Built-in resistance value R
f
(Typ value) = 10 M
Ω
, R
D
(Typ value) = 400 k
Ω
3. C
in
and C
out
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
Summary of Contents for SH7706 Series
Page 8: ...Rev 5 00 May 29 2006 page viii of xlviii ...
Page 160: ...Section 5 Cache Rev 5 00 May 29 2006 page 112 of 698 REJ09B0146 0500 ...
Page 370: ...Section 11 Watchdog Timer WDT Rev 5 00 May 29 2006 page 322 of 698 REJ09B0146 0500 ...
Page 554: ...Section 17 Pin Function Controller PFC Rev 5 00 May 29 2006 page 506 of 698 REJ09B0146 0500 ...
Page 576: ...Section 18 I O Ports Rev 5 00 May 29 2006 page 528 of 698 REJ09B0146 0500 ...
Page 746: ...Index Rev 5 00 May 29 2006 page 698 of 698 REJ09B0146 0500 ...
Page 749: ...SH7706 Group Hardware Manual ...