Datasheet

PIC18F66K80 FAMILY
DS39977C-page 50 Preliminary  2011 Microchip Technology Inc.
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 cir-
cuit 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.
Layout suggestions are shown in Figure 2-4. In-line
packages may be handled with a single-sided layout
that completely encompasses the oscillator pins. With
fine-pitch packages, it is not always possible to com-
pletely surround the pins and components. A suitable
solution is to tie the broken guard sections to a mirrored
ground layer. In all cases, the guard trace(s) must be
returned to ground.
TABLE 2-1 SUITABLE CAPACITOR EQUIVALENTS
Make Part #
Nominal
Capacitance
Base Tolerance Rated Voltage Temp. Range
TDK C3216X7R1C106K 10 µF ±10% 16V -55 to 125ºC
TDK C3216X5R1C106K 10 µF ±10% 16V -55 to 85ºC
Panasonic ECJ-3YX1C106K 10 µF ±10% 16V -55 to 125ºC
Panasonic ECJ-4YB1C106K 10 µF ±10% 16V -55 to 85ºC
Murata GRM32DR71C106KA01L 10 µF ±10% 16V -55 to 125ºC
Murata GRM31CR61C106KC31L 10 µF ±10% 16V -55 to 85ºC