Notes On Handling Devices - Fujitsu MB90420/5 (A) Series Hardware Manual

MB90420/5 (A) SERIES F

1.8 Notes on Handling Devices

When handling the devices, pay much attention to the following items:
• Conformance with maximum rated voltage (to prevent latch up)
• Stability of voltage supply
• At power-on
• Handling of unused input pins
• Handling of power pins of A/D converter
• When using external clock
• Power pins
• Input sequence of power analog input of A/D converter
• Pull-up/-down resistor
• Output of undefined values from port at power-on reset
l l Device handling
n Precautions when handling devices
• Conformance with maximum rated voltage (To prevent latch up)
For a CMOS IC, latch up may occur when a voltage higher than V
impressed to the I/O pin other than medium-/high-voltage withstand I/O pins, or when a voltage that
exceeds the rated voltage is impressed between V
Latch up rapidly increases the power current, and the device may be destroyed by heat.
When using the device, take care not to exceed the maximum rating. Also, take care that the analog
power (AV , AVRH, DV
CC
AC/DC power on or off.
• Stability of voltage supply
A sudden change in the power supply voltage may cause a malfunction even within the operating
assurance range of the V
frequency (50 to 60 MHz) must be 10% or less of the standard V
instantaneous change such as switching power switching must be 0.1 V/ms or less.
• At power-on
To prevent a malfunction of the internal voltage-lowering circuit, allow a voltage rise time of 50 µs (in range
of 0.2 to 2.7 V) or longer at power-on.
• Handling of unused input pins
If unused input pins remain open, a malfunction or latch up may cause permanent damage, so take
countermeasures such as pull-up or pull-down using a 2 kΩ or larger resistor.
Also, when there are unused I/O pins, set them to the output state and free them, or set them to the input
state and process like input pins.
• Handling of power pins of A/D converter
Even when the A/D converter is not used, connect the pins so that the following relationships are
established: AV = V
CC
2
MC-16LX FAMILY 16-BIT MICROCONTROLLERS HARDWARE MANUAL
) and the analog input do not exceed the digital power (V
CC
power supply voltage. For safety, the V
CC
, AV = AVRH = AVRL = V
CC SS
CC
and V .
CC SS
value, and the transient fluctuation at
CC
.
SS
1-16
or a voltage lower than V
) when turning the
CC
ripple (p-p) of the commercial
CC
is
SS