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5.3 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 and
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
possible at circumscription of the OSC1, OSC2, OSC3 and OSC4
terminals and the components connected to these terminals.
Furthermore, do not use this V
the oscillation system.
● In order to prevent unstable operation of the oscillation circuit due to current leak between OSC1/OSC3
and V
, please keep enough distance between OSC1/OSC3 and V
DD
tern.
<Reset Circuit>
● The power-on reset signal which is input to the RESET terminal changes depending on conditions (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 using the built-in pull-down resistor of the RESET terminal, take into consid-
eration dispersion of the resistance for setting the constant.
● In order to prevent any occurrences of unnecessary resetting caused by noise during operating, compo-
nents 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
large as possible.
(2) When connecting between the V
be connected as short as possible.
(3) Components which are connected to the V
should be connected in the shortest line.
In particular, the V
● Do not connect anything to the V
pattern for any purpose other than
SS
and V
DD
SS
Bypass capacitor connection example
V
DD
V
SS
–V
voltages affect the display quality.
C1
C5
–V
terminals when the LCD driver is not used.
C1
C5
pattern as large as
SS
DD
and V
terminals with patterns as short and
DD
SS
terminals with a bypass capacitor, the terminals should
V
DD
V
SS
, V
, V
and V
–V
D1
D2
OSC
C1
SIC63616-(Rev. 1.0) NO. P179
Sample V
pattern (OSC3)
SS
or other signals on the board pat-
terminals, such as capacitors,
C5
OSC4
OSC3
V
SS
3240-0412
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