SH7136 datasheet(99/1160 Pages) RENESAS

99 / 1160 page

Section 4 Clock Pulse Generator (CPG)

Rev. 2.00 Sep. 10, 2008 Page 73 of 1130

REJ09B0402-0200

4.8

Usage Notes

4.8.1

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 oscillator circuit's circuit constant

will depend on the resonator and the floating capacitance of the mounting circuit, the value of each

external circuit's component should be determined in consultation with the resonator

manufacturer. The design must ensure that a voltage exceeding the maximum rating is not applied

to the oscillator pin.

4.8.2

Notes on Board Design

Measures against radiation noise are taken in this LSI. If further reduction in radiation noise is

needed, it is recommended to use a multiple layer board and provide a layer exclusive to the

system ground.

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.

CL2

Signal A Signal B

This LSI

CL1

XTAL

EXTAL

Avoid

Figure 4.5 Cautions for Oscillator Circuit Board Design

SH7136 Datasheet(PDF) 99 Page - Renesas Technology Corp