SH7706 Datasheet, PDF (361/749 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/SH7700 Series

Section 10 Clock Pulse Generator (CPG)
10.6 Usage Note
When Using an External Crystal Oscillator: Place the crystal oscillator, capacitors CL1 and
CL2, close to the EXTAL and XTAL pins. To prevent induction from interfering with correct
oscillation, use a common grounding point for the capacitors connected to the oscillator, and do
not locate a wiring pattern near these components.
Avoid crossing
signal lines
CL1
CL2
EXTAL
XTAL
This LSI
Note: The values for CL1, and CL2 should be determined after
consultation with the crystal oscillator manufacturer.
Figure 10.2 Points for Attention when Using Crystal Oscillator
Decoupling Capacitors: As far as possible, insert a laminated ceramic capacitor of 0.1 to 1 µF as
a passive capacitor for each V_SS/V_CC pair. Mount the passive capacitors as close as possible to the
SH7706 power supply pins, and use components with a frequency characteristic suitable for the
chip's operating frequency, as well as a suitable capacitance value.
Digital system V_SS/V_CC pairs: 11 to 13, 19 to 21, 25 to 27, 37 to 39, 49 to 51, 61 to 63, 84 to 86, 93
to 95, 115 to 117, 137 to 139, 148 to 150, 156 to 158
On-chip oscillator V_SS/V_CC pairs: 1 to 4, 123 to 125, 126 to 128
When Using a PLL Oscillator Circuit: Keep the wiring from the PLL V_CC and V_SS connection
pattern to the power supply pins short, and make the pattern width large, to minimize the
inductance component. Ground the oscillation stabilization capacitors C1 and C2 to V_SS (PLL1)
and V_SS (PLL2), respectively. Place C1 and C2 close to the CAP1 and CAP2 pins and do not
locate a wiring pattern in the vicinity. In clock mode 7, connect the EXTAL pin to V_CCQ or V_SSQ
and leave the XTAL pin open.
Rev. 5.00 May 29, 2006 page 313 of 698
REJ09B0146-0500