Handling The Device - Fujitsu F2MC-16LX Hardware Manual

1.7

Handling the Device

This section gives notes on handling the MB90470.
I Notes on handling the device
❍ Latch-up prevision and power-on sequence
Some CMOS ICs may cause latch-up symptoms as described below:
• If voltages higher than V
• If the applied voltage ranging between V
• If voltage V
Analog voltage must be supplied at the same time as V
power supply is turned on. (Turn off the analog power supply before or at the same time as the
power supply is turned off.)
Once a latch-up occurs, the power supply current increases rapidly, possibly causing heat
damage in the element. Be sure to prevent such damage during use.
❍ Processing unused input pins
Keeping an unused input pin open may cause an error in operation. Apply pull-up or pull-down
to such pins as necessary. For an unused A/D converter, connect it so that AV
V , and AV
CC
❍ Handling a power supply pin (V
If multiple V
supply and ground externally in consideration of device design in order to decrease latch-up and
unnecessary radiation. Be sure to connect all power supply pins to the power supply or ground
so that the total output current specification is not exceeded. As much as possible, the power
supply source must be connected with V
recommends placing a bypass condenser of 0.1 µF between V
❍ Crystal oscillation circuit
Noise around the X0/X1 or X0A/X1A pins, if generated, may cause an error during operation on
this device. X0/X1, X0A/X1A and a crystal oscillator (or ceramic oscillator), or a bypass
condenser to ground must be arranged as close to each other as possible to prevent crossover
between them. Printed board artwork is strongly recommended since it is expected to provide
stable operation.
❍ Notes on using external clock
Use of the external clock requires a connection with an external pin, as shown in Figure 1.7-1
"Use of external clock".
Figure 1.7-1 "Use of external clock" shows a connection with the external clock (f=20 MHz or
below)
or lower than V
CC
is applied following the AV
CC
= V .
SS SS
/V
CC
and/or V are used, all power supply pins must be connected with a power
CC SS
CHAPTER 1 OVERVIEW OF MB90470
are applied to the input and output pins.
SS
and V is higher than the rated voltage.
CC SS
power supply
CC
, or it must be applied after the digital
CC
)
SS
/V of this device at the lowest impedance. Fujitsu
CC SS
CC
= AVRH =
CC
and V .
SS
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