■ Note for the Case of Using No Subclock
When the oscillator is not connect to the X0A,X1A pins, set the X0A pin to the pull-down operation and
open the X1A pin.
■ Handling of NC and Open Pins
NC and open pins must be left open.
■ Mode Pins (MD0 to MD2)
These pins must be directly connected to V
a mode pin on a printed circuit board and V
At power-on, be sure to set the INIT pin to the low level.
Also immediately after power-on, keep the INIT pin at the L level until the oscillator has reached the
required frequency stability. (For initialization by INIT from the INIT pin, the oscillation stabilization wait
time is set to the minimum value.)
■ Source Oscillation Input at Power-on
At power-on, be sure to input a source clock until the oscillation stabilization wait time is cleared.
■ Note on Operating in PLL Clock Mode
If the PLL clock mode is selected, the microcontroller attempt to be working with the self-oscillating circuit
even when there is no external oscillator or external clock input is stopped. Performance of this operation,
however, cannot be guaranteed.
■ Setting the External Bus
The MB91350A model type guarantees a 25 MHz external bus.
If the base clock is set to 50 MHz without the DIVR1 (external bus base clock freq.-divide setting register)
initial value being unchanged, the external bus will also be set to 50 MHz. When changing the base clock,
first set the external bus so that it does not exceed 25 MHz and then change the base clock.
■ MCLK and SYSCLK
The difference between MCLK and SYSCLK is that MCLK stops in sleep mode and stop mode whereas
SYSCLK stops only in stop mode. Use MCLK or SYSCLK, whichever is appropriate.
After initialization, MCLK is disabled (PORT) and SYSCLK is enabled. To use MCLK, you must set the
port function register (PFR) to use MCLK.
Figure 2.1-2 Setting for the Case of Using No Subclock
when they are used. Keep the pattern length between
as short as possible so that they can be connected at a