PIC18F44J10T-I/ML(2009) View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
PIC18F44J10T-I/ML
(Rev.:2009)
(Rev.:2009)
Microchip Technology
PIC18F44J10T-I/ML Datasheet PDF : 368 Pages
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PIC18F45J10 FAMILY
2.6 External Oscillator Pins
Many microcontrollers have options for at least two
oscillators: a high-frequency primary oscillator and a
low-frequency secondary oscillator (refer to
Section 3.0 “Oscillator Configurations” for details).
The oscillator circuit should be placed on the same
side of the board as the device. Place the oscillator
circuit close to the respective oscillator pins with no
more than 0.5 inch (12 mm) between the circuit
components and the pins. The load capacitors should
be placed next to the oscillator itself, on the same side
of the board.
Use a grounded copper pour around the oscillator
circuit to isolate it from surrounding circuits. The
grounded copper pour should be routed directly to the
MCU ground. Do not run any signal traces or power
traces inside the ground pour. Also, if using a
two-sided board, avoid any traces on the other side of
the board where the crystal is placed. A suggested
layout is shown in Figure 2-4.
For additional information and design guidance on
oscillator circuits, please refer to these Microchip
Application Notes, available at the corporate web site
(www.microchip.com):
• AN826, “Crystal Oscillator Basics and Crystal
Selection for rfPIC™ and PICmicro® Devices”
• AN849, “Basic PICmicro® Oscillator Design”
• AN943, “Practical PICmicro® Oscillator Analysis
and Design”
• AN949, “Making Your Oscillator Work”
FIGURE 2-4:
SUGGESTED PLACEMENT
OF THE OSCILLATOR
CIRCUIT
Main Oscillator
13
Guard Ring
14
15
Guard Trace
16
Secondary
17
Oscillator
18
19
20
2.7 Unused I/Os
Unused I/O pins should be configured as outputs and
driven to a logic low state. Alternatively, connect a 1 kΩ
to 10 kΩ resistor to VSS on unused pins and drive the
output to logic low.
DS39682E-page 26
© 2009 Microchip Technology Inc.
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