SH7101 Datasheet, PDF (84/486 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

4. Clock Pulse Generator
4.3 Usage Notes
4.3.1 Note on Crystal Resonator
A sufficient evaluation at the user's site is necessary to use the LSI, by referring the resonator
connection examples shown in this section, because various characteristics related to the crystal
resonator are closely linked to the user's board design. As the resonator circuit ratings will depend
on the resonator and the floating capacitance of the mounting circuit, the ratings should be
determined in consultation with the resonator manufacturer. Ensure that a voltage exceeding the
maximum rating is not applied to the oscillator pin.
4.3.2 Notes on Board Design
Measures against radiation noise are taken in this LSI. If radiation noise needs to be further
reduced, usage of a multi-layer printed circuit board with ground planes is recommended.
When using a crystal resonator, place the crystal resonator and its load capacitors as close as
possible to the XTAL and EXTAL pins. Do not route any signal lines near the oscillator circuitry
as shown in figure 4.5. Otherwise, correct oscillation can be interfered by induction.
Avoid
C_L2
Signal A Signal B
This LSI
XTAL
EXTAL
C_L1
Figure 4.5 Cautions for Oscillator Circuit System Board Design
A circuitry shown in figure 4.6 is recommended as an external circuitry around the PLL. Place
oscillation stabilization capacitor C1 close to the PLLCAP pin, and ensure that no other signal
lines cross this line. Separate PLLV_CL, PLLV_SS, V_CC, and V_SS from the board power supply source,
and be sure to insert bypass capacitors CB close to the pins.
Rev.2.00 Sep. 27, 2007 Page 50 of 448
REJ09B0394-0200