APPENDIX D PRECAUTIONS ON MOUNTING
AP-34
EPSON
S1C17704 TECHNICAL MANUAL
Appendix D Precautions on Mounting
The following shows the precautions when designing the board and mounting the IC.
Oscillator Circuit
• Oscillation characteristics change depending on conditions such as components used (resonator, R
f
, C
G
,
C
D
) and board pattern. In particular, when a ceramic or crystal resonator is used, evaluate the components
adequately under real operating conditions by mounting them on the board before the external register (R
f
) and
capacitor (C
G
, C
D
) values are finally decided.
• Disturbances of the oscillation clock due to noise may cause a malfunction. To prevent this, the following
points should be taken into consideration. In particular, the latest devices are more sensitive to noise, as they are
more finely processed.
The measures against noise for the OSC2 pin, and the components and lines connected to this pin is most
essential, and similar measures must also be taken for the OSC1 pin. The measures for the OSC1 and OSC2
pins are described below.
We recommend taking measures similar to those for the high-speed oscillation system, including the OSC3 and
OSC4 pins and the components and lines connected to these pins.
(1) Components that are connected to the OSC1 (OSC3) and OSC2 (OSC4) pins, such as resonators, resistors,
and capacitors, should be connected in the shortest line.
(2) Whenever possible, configure digital signal lines with at least three millimeters clearance from the OSC1
(OSC3) and OSC2 (OSC4) pins and the components and lines connected to these pins. In particular, signals
that are switched frequently must not be placed near these pins, components, and lines. The same applies to
all layers on the multi-layered board as the distance between the layers is around 0.1 to 0.2 mm.
Furthermore, do not configure digital signal lines in parallel with these components and lines when
arranging them on the same or another layer of the board. Such an arrangement is strictly prohibited,
even with clearance of three millimeters or more. Also, avoid arranging digital signal lines across these
components and signal lines.
(3) Shield the OSC1 (OSC3) and OSC2 (OSC4) pins and lines connected to those
pins as well as the adjacent layers of the board using V
SS
.
As shown in the figure on the right, shield the wired layers as much as
possible.
Whenever possible, make the whole adjacent layers the ground layers, or
ensure there is adequate shielding to a radius of five millimeters around the
above pins and lines.
As described in (2), do not configure digital signal lines in parallel with
components and lines even if such precautionary measures are taken, and
avoid configuring signal lines that are switched frequently across components
and lines on other layers.
(4) After taking the above precautions, check the output clock waveform while operating the actual application
program in the actual device.
To do this, measure the output of the FOUT1/FOUT3 pins with an oscilloscope.
Check the waveform quality at the OSC3 output clock by measuring the FOUT3 output. Ensure that the
frequencies are as designed and that there is no noise or jitters.
Check the waveform quality at the OSC1 clock by measuring the FOUT1 output. Scale up the ranges
around the rising and falling edges of the clock pulse to ensure that there is no noise, such as clock and
spike, in the 100 ns ranges.
If conditions (1) to (3) are not satisfied, the OSC3 output may be jittery and the OSC1 output may be noisy.
When the OSC3 output is jittery, the operating frequency will be lowered. When the OSC1 output is noisy,
operation of the timers using the OSC1 clock and the CPU core after the system clock is switched to OSC1
will be unstable.
OSC4
OSC3
V
SS
Sample V
SS
pattern (OSC3)
Summary of Contents for S1C17704
Page 1: ...TECHNICAL MANUAL S1C17704 CMOS 16 BIT SINGLE CHIP MICROCOMPUTER ...
Page 22: ...1 OVERVIEW 1 10 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 42: ...3 MEMORY MAP BUS CONTROL 3 12 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 82: ...6 INTERRUPT CONTROLLER ITC 6 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 108: ...8 CLOCK GENERATOR CLG 8 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 112: ...9 PRESCALER PSC 9 4 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 138: ...10 I O PORTS P 10 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 156: ...11 16 BIT TIMERS T16 11 18 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 208: ...14 8 BIT OSC1 TIMER T8OSC1 14 16 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 234: ...16 STOPWATCH TIMER SWT 16 14 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 242: ...17 WATCHDOG TIMER WDT 17 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 264: ...18 UART 18 22 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 300: ...20 I2C 20 20 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 320: ...21 REMOTE CONTROLLER REMC 21 20 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 360: ...24 ON CHIP DEBUGGER DBG 24 6 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 362: ...25 BASIC EXTERNAL WIRING DIAGRAM 25 2 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...