Usage Notes - Renesas H8S Family Hardware Manual

Section 27 Clock Pulse Generator

27.8

Note on Resonator

Since all kinds of characteristics of the resonator are closely related to the board design by the

user, use the example of resonator connection in this document for only reference; be sure to use

an resonator that has been sufficiently evaluated by the user. Consult with the resonator

manufacturer about the resonator circuit ratings which vary depending on the stray capacitances of

the resonator and installation circuit. Make sure the voltage applied to the oscillation pins do not

exceed the maximum rating.

Notes on Board Design

When using a crystal resonator, the crystal resonator and its load capacitors should be placed as

close as possible to the EXTAL and XTAL pins. Other signal lines should be routed away from

the oscillation circuit to prevent inductive interference with the correct oscillation as shown in

figure 27.5.

Figure 27.5 Note on Board Design of Oscillation Circuit Section

Note on Operation Check

This LSI may oscillate at several kHz of frequency even when a crystal resonator is not connected

to the EXTAL and XTAL pins or an external clock is not input. Use this LSI after confirming that

the LSI operates with appropriate frequency.

Rev. 1.00 Mar. 12, 2008 Page 1056 of 1178

REJ09B0403-0100

Signal A Signal B