SH7046 Datasheet, PDF (93/611 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7046 Series

Section 4 Clock Pulse Generator
Even when inputting an external clock, be sure to wait at least the oscillation stabilization time in
power-on sequence or in releasing standby mode, in order to ensure the PLL stabilization time.
EXTAL
XTAL
External clock input
Open state
Figure 4.4 Example of External Clock Connection
4.2 Function for Detecting the Oscillator Halt
This CPG can detect a clock halt and automatically cause the timer pins to become high-
impedance when any system abnormality causes the oscillator to halt. That is, when a change of
EXTAL has not been detected, the high-current 12 pins (PE9/TIOC3B, PE11/TIOC3D,
PE12/TIOC4A, PE13/TIOC4B/MRES, PE14/TIOC4C, PE15/TIOC4D/IRQOUT, PE16/PUOA/
UBCTRG^*, PE17/PVOA, PE18/PWOA, PE19/PUOB, PE20/PVOB, PE21/PWOB) are set to
high-impedance regardless of PFC setting.
Even in standby mode, these 12 pins become high-impedance regardless of PFC setting. These
pins enter the normal state after standby mode is released. When abnormalities that halt the
oscillator occur except in standby mode, other LSI operations become undefined. In this case, LSI
operations, including these 12 pins, become undefined even when the oscillator operation starts
again.
Note: * For flash version only
4.3 Usage Notes
4.3.1 Note on Crystal Resonator
A sufficient evaluation at the user’s site is necessary to use the LSI, by referring the resonator
connection examples shown in this section, because various characteristics related to the crystal
resonator are closely linked to the user’s board design. As the resonator circuit constants will
depend on the resonator and the floating capacitance of the mounting circuit, the component value
should be determined in consultation with the resonator manufacturer. Ensure that a voltage
exceeding the maximum rating is not applied to the oscillator pin.
Rev. 4.00 Dec 05, 2005 page 49 of 564
REJ09B0270-0400