SH7040 Datasheet, PDF (121/923 Pages) Renesas Technology Corp – Renesas 32-Bit Single-Chip RISC Microprocessor SuperH RISC engine Family/SH7040 Series(CPU Core SH-2)

When leaving the XTAL pin open, make sure the parasitic capacitance is less than 10 pF.
Even when inputting an external clock, be sure to delay until after the oscillation stabilization time
(upon power-on) or after release from standby, in order to ensure the PLL stabilization time.
EXTAL
XTAL
Open
External clock
input 4–10 MHz
Figure 4.4 Example of External Clock Connection
4.3 Prescaler
The prescaler divides the system clock (φ) to generate an internal clock (φ/2 to φ/8192) for supply
to peripheral modules.
4.4 Oscillator Halt Function
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 six pins (PE9/TIOC3B, PE11/TIOC3D,
PE12/TIOC4A, PE13/TIOC4B/MRES, PE14/TIOC4C/DACK0/AH, PE15/TIOC4D/DACK1/
IRQOUT) are set to high-impedance regardless of PFC setting.
Even in standby mode, these six pins become high-impedance regardless of PFC setting. These
pins enter the normal state after standby mode is cancelled.When abnormalities that halt the
oscillator occur except in standby mode, other LSI operations become undefined. In this case, LSI
operations, including these six pins, become undefined even when the oscillator operation starts
again.
4.5 Usage Notes
4.5.1 Oscillator Usage Notes
Since the characteristics of the oscillator are closely related to the user-defined board settings, the
user should refer to the connection examples in this section and perform a careful evaluation. The
oscillator circuit ratings will differ depending on factors such as the oscillator used and the stray
capacitance of the mounted circuitry. Therefore, the oscillator manufacturer should be consulted
before a decision is made. Make sure that the voltage applied to the oscillator does not exceed the
maximum rating.
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