Usage Notes; Note On Crystal Resonator; Note On Board Design; Figure 19.6 Note On Board Design Of Oscillator Circuit - Renesas H8S Series Hardware Manual

Section 19 Clock Pulse Generator
19.6

Usage Notes

19.6.1

Note on Crystal Resonator

As various characteristics related to the crystal resonator are closely linked to the user's board
design, thorough evaluation is necessary on the user's part, using the resonator connection
examples shown in this section as a guide. As the resonator circuit ratings will depend on the
floating capacitance of the resonator and the mounting circuit, the ratings 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.
19.6.2

Note on Board Design

When designing the board, place the crystal resonator and its load capacitors as close as possible
to the XTAL and EXTAL pins. Other signal lines should be routed away from the oscillator
circuit, as shown in figure 19.6. This is to prevent induction from interfering with correct
oscillation.

Figure 19.6 Note on Board Design of Oscillator Circuit

Figure 19.7 shows external circuitry recommended to be provided around the PLL circuit. Place
oscillation stabilization capacitor C1 and resistor R1 close to the PLLCAP pin, and ensure that no
other signal lines cross this line. Separate PLLVc
at the board power supply source, and be sure to insert bypass capacitors CB close to the pins.
Rev. 6.00 Mar 15, 2006 page 488 of 570
REJ09B0211-0600
Signal A Signal B
Avoid
C
L2
C
L1
L
This LSI
XTAL
EXTAL
and PLLVss from the other Vcc and Vss lines