MB90385 Series
s
HANDLING DEVICES
•
Do Not Exceed Maximum Rating (preventing “latch up”)
• On a CMOS IC, latch-up may occur when applying a voltage higher than Vcc or a voltage lower than Vss to
input or output pin, which has no middle or high withstand voltage. Latch-up may also occur when a voltage
exceeding maximum rating is applied across Vcc and Vss.
• Latch-up causes drastic increase of power current, which may lead to destruction of elements by heat. Extreme
caution must be taken not to exceed maximum rating.
• When turning on and off analog power source, take extra care not to apply an analog power voltages (AVcc
and AVR) and analog input voltage that are higher than digital power voltage (Vcc).
•
Handling Unused Pins
• Leaving unused input pins open may cause permanent destruction by malfunction or latch-up. Apply pull-up
or pull-down process to the unused pins using resistors of 2 kΩ or higher. Leave unused input pins open under
output status, or process as input pins if they are under input status.
•
Using External Clock
• When using an external clock, drive only X0 pin and leave X1 pin open. An example of using an external clock
is shown below.
•
Using external clock
X0
Open
X1
MB90385 series
•
Notes When Using No Sub Clock
• If an oscillator is not connected to X0A and X1A pin, apply pull-down resistor to X0A pin and leave X1A pin open.
•
About Power Supply Pins
• If two or more Vcc and Vss exist, the pins that should be at the same potential are connected to each other
inside the device. For reducing unwanted emissions and preventing malfunction of strobe signals caused by
increase of ground level, however, be sure to connect the Vcc and Vss pins to the power source and the ground
externally.
• Pay attention to connect a power supply to Vcc and Vss of MB90385 series device in a lowest-possible
impedance.
• Near pins of MB90385 series device, connecting a bypass capacitor is recommended at 0.1
µF
across Vcc
and Vss.
•
Crystal Oscillator Circuit
• Noises around X0 and X1 pins cause malfunctions on a MB90385 series device. Design a print circuit so that
X0 and X1 pins, an crystal oscillator (or a ceramic oscillator), and bypass capacitor to the ground become as
close as possible to each other. Furthermore, avoid wires to X0 and X1 pins crossing each other as much as
possible.
• Print circuit designing that surrounds X0 and X1 pins with grounding wires, which ensures stable operation,
is strongly recommended.
•
Caution on Operations during 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.
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