SH7280 Datasheet, PDF (124/1726 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine family

Section 4 Clock Pulse Generator (CPG)
4.9 Notes on Board Design
4.9.1 Note on Using an External Crystal Resonator
Place the crystal resonator and capacitors CL1 and CL2 as close to the XTAL and EXTAL pins as
possible. In addition, to minimize induction and thus obtain oscillation at the correct frequency,
the capacitors to be attached to the resonator must be grounded to the same ground. Do not bring
wiring patterns close to these components.
Signal lines prohibited
CL1
CL2
Reference value
CL1 = 20 pF
CL2 = 20 pF
EXTAL
XTAL
This LSI
Note:
The values for CL1 and CL2
should be determined after
consultation with the crystal
resonator manufacturer.
Figure 4.9 Note on Using a Crystal Resonator
A circuitry shown in figure 4.10 is recommended as an external circuitry around the PLL. PLLVss
must be separated from Vcc and Vss at the board power supply source. Be sure to insert bypass
capacitors CB and CPB close to the Vcc and Vss pins.
PLLV_SS
V_CL
V_CC
V_SS
CPB = 0.1 µF*
CB = 0.1 µF*
Note: * CB and CPB are laminated ceramic capacitors.
(Recommended values are shown.)
Figure 4.10 Recommended External Circuitry around PLL
Rev. 1.00 Jun. 26, 2008 Page 94 of 1692
REJ09B0393-0100