R5S72011 RENESAS [Renesas Technology Corp], R5S72011 Datasheet - Page 690

• Manufacturer Part Number: R5S72011
• Description: 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 15 Realtime Clock (RTC)
15.5.3
When a transition to standby mode is made after registers in the RTC are set, sometimes counting
is not performed correctly. In case the registers are set, be sure to make a transition to standby
mode after waiting for two RTC clocks or more.
15.5.4
Crystal oscillator circuit constants (recommended values) for the RTC are shown in table 15.3, and
the RTC crystal oscillator circuit in figure 15.6.
Table 15.3 Crystal Oscillator Circuit Constants (Recommended Values)
Rev. 2.00 Sep. 07, 2007 Page 662 of 1164
REJ09B0321-0200
f
32.768 kHz
osc
Notes: 1. Select either the C
7. When crystal oscillation circuit for RTC is not used, connect the RTC_X1 pin to GND and leave the RTC_X2
2. Built-in resistance value R
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 stabilization time may differ depending on the mounted circuit component constants,
5. Place the crystal resonator and load capacitors C
6. Ensure that the wiring of the crystal oscillator connection pins (RTC_X1 and RTC_X2) is routed as far away as
Transition to Standby Mode after Setting Register
Crystal Oscillator Circuit for RTC
as frequency range, degree of stability, etc.
stray capacitance, and so forth, so a suitable value should be determined in consultation with the resonator
manufacturer.
length as short as possible. Do not allocate signal lines close to oscillation circuit.
(Correct oscillation may not be possible if there is externally induced noise in the RTC_X1 and RTC_X2 pins.)
possible from the power lines (except GND) and signal lines.
pin open
Figure 15.6 Example of Connecting Crystal Oscillator Circuit for RTC
This LSI
in
or C
out
f
(Typ value) = 10 MΩ, R
side for frequency adjustment variable capacitor according to requirements such
C
10 to 22 pF
RTC_X1
in
C
in
R
f
XTAL
in
D
and C
(Typ value) = 400 kΩ
out
R
RTC_X2
as close as possible to the chip. Make wiring
D
C
out
C
10 to 22 pF
out