Specifications

7 Mounting

S1C33 ASIC DESIGN GUIDE

EPSON

EMBEDDED ARRAY S1X50000 SERIES

Chapter 7 Mounting

7.1 Precautions on Mounting

The following shows the precautions when designing the board and mounting the IC.

Oscillation Circuit

• Oscillation characteristics change depending on conditions (board pattern, compo-

nents 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 OSC3 (OSC1), OSC4 (OSC2) and PLLC

pins, such as oscillators, resistors and capacitors, should be connected in the shortest

line.

(2) As shown in the figure below, make a V

pattern as large as possible at circum-

scription of the OSC3 (OSC1) and OSC4 (OSC2) pins and the components connect-

ed to these pins. The same applies to the PLLC pin.

Furthermore, do not use this V

pattern to connect other components than the os-

cillation system.

Figure 7.1 Sample V

Pattern

(3) When supplying an external clock to the OSC3 (OSC1) pin, the clock source should

be connected to the OSC3 (OSC1) pin in the shortest line.

Furthermore, do not connect anything else to the OSC4 (OSC2) pin.

• In order to prevent unstable operation of the oscillation circuit due to current leak

between OSC3 (OSC1) and V

, please keep enough distance between OSC3

(OSC1) and V

or other signals on the board pattern.

OSC4

OSC3

OSC3, OSC4

PLLC