Precautions On Handling The Device - Fujitsu FR60 Hardware Manual

CHAPTER 2 HANDLING THE DEVICE
2.1

Precautions on Handling the Device

This section contains information on the prevention of latch-ups, pin processing,
handling of circuits, input at power-on and so on.
■ Preventing a Latch-up
A latch-up can occur if, on a CMOS IC, a voltage higher than V
an input or output pin or a voltage higher than the rating is applied between V
occurs, significantly increases the power supply current and may cause thermal destruction of an element.
When you use a CMOS IC, be very careful not to exceed the maximum rating.
■ Unused Input Pins
Do not leave an unused input pin open, since it may cause a malfunction. Handle by, for example, using a
pull-up or pull-down resistor.
■ Power Supply Pins
If more than one V
connected to one other inside the device to prevent malfunctions such as latch-up. Be sure to connect the
pins to a power supply and ground external to the device to minimize undesired electromagnetic radiation,
prevent strobe signal malfunctions due to an increase in ground level, and conform to the total output
current rating. Given consideration to connecting the current supply source to V
the lowest impedance possible.
It is also recommended that a ceramic capacitor of around 0.1 µF be connected between V
circuit points close to the device as a bypass capacitor.
■ Quartz Oscillation Circuit
Noise near the X0, X1, X0A, and X1A pins may cause the device to malfunction. Design printed circuit
boards so that X0 and X1, X0A and X1A, the quartz oscillator (or ceramic oscillator), and the bypass
capacitor to ground are located as near as possible to one another.
In addition, it is strongly recommended that printed circuit board artwork that surrounds the X0, X1, X0A,
and X1A pins with ground be used to make stable operation more likely.
■ Note on Using an External Clock
When an external clock is used, use the X0 pin unless otherwise specify and supply a negative-phase clock
to the X1 pin simultaneously. Do not use STOP mode (oscillation stop mode) for this operation because the
X1 pin is disabled when H is output at STOP.
Figure 2.1-1 Example of Using an External Clock (Normal Method)
32
or V pin exists, those that must be kept at the same potential are designed to be
CC SS
Note: STOP mode (oscillation stop mode) cannot be used.
or a voltage lower than V
CC
X0
X1
is applied to
SS
and V . A latch-up, if it
CC SS
and V of the device at
cc SS
and V
CC SS
at