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10 PRECAUTIONS ON MOUNTING
<Oscillation Circuit>
Oscillation characteristics change depending on
conditions (board pattern, components used,
etc.).
In particular, when a ceramic oscillator or
crystal oscillator is used, use the oscillator
manufacturer's recommended values for
constants such as capacitance and resistance.
Disturbances of the oscillation clock due to
noise may cause a malfunction. Consider the
following points to prevent this:
(1) Components which are connected to the
OSC1, OSC2, OSC3, OSC4 terminals, such as
oscillators, resistors and capacitors, should
be connected in the shortest line.
(2) As shown in the right hand figure, make a
V
pattern as large as possible at circum-
SS
scription of the OSC1, OSC2, OSC3, OSC4
terminals and the components connected to
these terminals.
Furthermore, do not use this V
any purpose other than the oscillation
system.
Sample V
pattern (OSC3)
SS
(3) When supplying an external clock to the
OSC1 (OSC3) terminal, the clock source
should be connected to the OSC1 (OSC3)
terminal in the shortest line.
Furthermore, do not connect anything else
to the OSC2 (OSC4) terminal.
In order to prevent unstable operation of the
oscillation circuit due to current leak between
OSC1 (OSC3) and V
distance between OSC1 (OSC3) and V
other signals on the board pattern.
E0C88832/88862 TECHNICAL MANUAL
pattern for
SS
OSC4
OSC3
V
SS
, please keep enough
DD
or
DD
<Reset Circuit>
The power-on reset signal which is input to the
RESET terminal changes depending on condi-
tions (power rise time, components used, board
pattern, etc.).
Decide the time constant of the capacitor and
resistor after enough tests have been completed
with the application product.
When the built-in pull-up resistor is added to
the RESET terminal by mask option, take into
consideration dispersion of the resistance for
setting the constant.
In order to prevent any occurrences of unneces-
sary resetting caused by noise during operating,
components such as capacitors and resistors
should be connected to the RESET terminal in
the shortest line.
<Power Supply Circuit>
Sudden power supply variation due to noise
may cause malfunction. Consider the following
points to prevent this:
(1) The power supply should be connected to the
V
and V
terminals with patterns as short
DD
SS
and large as possible.
(2) When connecting between the V
terminals with a bypass capacitor, the terminals
should be connected as short as possible.
Bypass capacitor connection example
(3) Components which are connected to the V
V
–V
and CA–CG terminals, such as capaci-
C1
C5
tors, should be connected in the shortest line.
In particular, the V
display quality.
Do not connect anything to the V
CA–CG terminals when the LCD driver is not
used.
EPSON
10 PRECAUTIONS ON MOUNTING
and V
DD
V
DD
V
SS
–V
voltages affect the
C1
C5
–V
C1
C5
SS
V
DD
V
SS
,
D1
and
149
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