Datasheet

Section 22 Clock Pulse Generator
Rev.6.00 Mar. 18, 2009 Page 820 of 980
REJ09B0050-0600
22.5.2 Notes on Oscillator
Since various characteristics related to the oscillator are closely linked to the user’s board design,
thorough evaluation is necessary on the user’s part, using the oscillator connection examples
shown in this section as a guide. As the oscillator circuit ratings will depend on the floating
capacitance of the oscillator and the mounting circuit, the ratings should be determined in
consultation with the oscillator manufacturer. The design must ensure that a voltage exceeding the
maximum rating is not applied to the oscillator pin.
22.5.3 Notes on Board Design
When using the crystal oscillator, place the crystal oscillator 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 to prevent induction from interfering with correct oscillation. See figure 22.6.
C
L2
Signal A Signal B
C
L1
This LSI
XTAL
EXTAL
Avoid
Figure 22.6 Note on Oscillator Board Design
Figure 22.7 shows the external circuitry recommended for the PLL circuit. Separate PLLVcc and
PLLVss from the other Vcc and Vss lines at the board power supply source, and be sure to insert
bypass capacitors CPB and CB close to the pins.