3 precautions on mounting, Oscillation circuit, Reset circuit – Epson S1C63558 User Manual

Page 167: Power supply circuit

S1C63558 TECHNICAL MANUAL

EPSON

157

CHAPTER 5: SUMMARY OF NOTES

5.3 Precautions on Mounting

● 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

pattern as large as

possible at circumscription of the OSC1, OSC2, OSC3 and OSC4
terminals and the components connected to these terminals.
Furthermore, do not use this V

pattern for any purpose other

than the oscillation system.

OSC4

OSC3

Sample V

pattern (OSC3)

● 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

or other signals on the

board pattern.

● 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 the built-in pull-up resistor is added to the RESET terminal by mask option, take into consider-
ation dispersion of the resistance for setting the constant.

● In order to prevent any occurrences of unnecessary resetting caused by noise during operating,

components such as capacitors and resistors should be connected to the RESET terminal in the
shortest line.

● 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 and

large as possible.

(2) When connecting between the V

and 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

and V

–V

terminals, such as capacitors, should be

connected in the shortest line.
In particular, the V

–V

voltages affect the display quality.

● Do not connect anything to the V

–V

terminals when the LCD driver is not used.