SH7670 Datasheet, PDF (385/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 9 Clock Pulse Generator (CPG)
9.6 Notes on Board Design
9.6.1 Note on Inputting External Clock
Figure 9.2 is an example of connecting the external clock input. When putting the XTAL pin in
open state, make sure the parasitic capacitance is less than or equal to 10 pF. To stably input the
external clock with enough PLL stabilizing time at power on or releasing the standby, wait longer
than the oscillation stabilizing time.
EXTAL
XTAL
External clock input
Open state
Example of connection with XTAL pin open
Figure 9.2 Example of Connecting External Clock
9.6.2 Note on Using an External Crystal Resonator
Place the crystal resonator and capacitors CL1 and CL2 as close to the XTAL and EXTAL pins as
possible. In addition, to minimize induction and thus obtain oscillation at the correct frequency,
the capacitors to be attached to the resonator must be grounded to the same ground. Do not bring
wiring patterns close to these components.
Signal lines prohibited
CL1
CL2
Reference value
CL1 = 10 pF
CL2 = 10 pF
EXTAL
XTAL
This LSI
Note:
The values for CL1 and CL2
should be determined after
consultation with the crystal
resonator manufacturer.
Figure 9.3 Note on Using a Crystal Resonator
Rev. 1.00 Nov. 14, 2007 Page 359 of 1262
REJ09B0437-0100