Document Number: 002-04713 Rev.*A
Page 30 of 65
MB96640 Series
13.3.2 Single phase external clock for Sub oscillator
When using a single phase external clock for the Sub oscillator,
“External clock mode” must be selected and
X0A/P04_0 pin must be driven. X1A/P04_1 pin can be configured as GPIO.
13.3.3 Opposite phase external clock
When using an opposite phase external clock, X1 (X1A) pins must be supplied with a clock signal which has
the opposite phase to the X0 (X0A) pins. Supply level on X0 and X1 pins must be 1.8V.
13.4 Notes on PLL clock mode operation
If the microcontroller is operated with PLL clock mode and no external oscillator is operating or no external clock is supplied, the
microcontroller attempts to work with the free oscillating PLL. Performance of this operation, however, cannot be guaranteed.
13.5 Power supply pins (V
cc
/V
ss
)
It is required that all V
CC
-level as well as all V
SS
-level power supply pins are at the same potential. If there is more than one V
CC
or
V
SS
level, the device may operate incorrectly or be damaged even within the guaranteed operating range.
V
cc
and V
ss
pins must be connected to the device from the power supply with lowest possible impedance.
The smoothing capacitor at V
cc
pin must use the one of a capacity value that is larger than Cs.
Besides this, as a measure against power supply noise, it is required to connect a bypass capacitor of about 0.1
F between V
cc
and
V
ss
pins as close as possible to V
cc
and V
ss
pins.
13.6 Crystal oscillator and ceramic resonator circuit
Noise at X0, X1 pins or X0A, X1A pins might cause abnormal operation. It is required to provide bypass capacitors with shortest
possible distance to X0, X1 pins and X0A, X1A pins, crystal oscillator (or ceramic resonator) and ground lines and to the utmost
effort, that the lines of oscillation circuit do not cross the lines of other circuits.
It is highly recommended to provide a printed circuit board art work surrounding X0, X1 pins and X0A, X1A pins with a ground area
for stabilizing the operation.
It is highly recommended to evaluate the quartz/MCU or resonator/MCU system at the quartz or resonator manufacturer, especially
when using low-Q resonators at higher frequencies.
13.7 Turn on sequence of power supply to A/D converter and analog inputs
It is required to turn the A/D converter power supply (AV
CC
, AVRH, AVRL) and analog inputs (ANn) on after turning the digital power
supply (V
CC
) on.
It is also required to turn the digital power off after turning the A/D converter supply and analog inputs off. In this case, AVRH must
not exceed AV
CC
. Input voltage for ports shared with analog input ports also must not exceed AV
CC
(turning the analog and digital
power supplies simultaneously on or off is acceptable).
X0
X1
