Datasheet

Section 23 Clock Pulse Generator
Page 1212 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
23.5.3 Notes on Board Design
When using the crystal resonator, 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
oscillation circuit to prevent induction from interfering with correct oscillation. See figure 23.6.
C
L2
Signal A Signal B
C
L1
This LSI
XTAL
EXTAL
Prohibited
Figure 23.6 Note on Board Design for Oscillation Circuit
Figure 23.7 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.
PLLV
CC
PLLV
SS
V
CC
V
SS
CPB: 0.1 µF
*
CB: 0.1 µF
*
Note: * CB and CPB are laminated ceramic capacitors.
Figure 23.7 Recommended External Circuitry for PLL Circuit