Microchip Technology MCU PIC PIC18F87K22-I/PTRSL TQFP-80 MCP PIC18F87K22-I/PTRSL Hoja De Datos
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PIC18F87K22-I/PTRSL
PIC18F87K22 FAMILY
DS39960D-page 50
2009-2011 Microchip Technology Inc.
3.5
External Oscillator Modes
3.5.1
CRYSTAL OSCILLATOR/CERAMIC
RESONATORS (HS MODES)
RESONATORS (HS MODES)
In HS or HSPLL Oscillator modes, a crystal or ceramic
resonator is connected to the OSC1 and OSC2 pins to
establish oscillation.
resonator is connected to the OSC1 and OSC2 pins to
establish oscillation.
connections.
The oscillator design requires the use of a crystal rated
for parallel resonant operation.
The oscillator design requires the use of a crystal rated
for parallel resonant operation.
TABLE 3-2:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
CERAMIC RESONATORS
TABLE 3-3:
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
CRYSTAL OSCILLATOR
FIGURE 3-4:
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS OR HSPLL
CONFIGURATION)
RESONATOR OPERATION
(HS OR HSPLL
CONFIGURATION)
Note:
Use of a crystal rated for series resonant
operation may give a frequency out of the
crystal manufacturer’s specifications.
operation may give a frequency out of the
crystal manufacturer’s specifications.
Typical Capacitor Values Used:
Mode
Freq.
OSC1
OSC2
HS
8.0 MHz
16.0 MHz
27 pF
22 pF
22 pF
27 pF
22 pF
22 pF
Capacitor values are for design guidance only.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
DD
and temperature range for the application. Refer
to the following application notes for oscillator-specific
information:
information:
• AN588, “PIC
®
Microcontroller Oscillator Design
Guide”
• AN826, “Crystal Oscillator Basics and Crystal
Selection for rfPIC
®
and PIC
®
Devices”
• AN849, “Basic PIC
®
Oscillator Design”
• AN943, “Practical PIC
®
Oscillator Analysis and
Design”
• AN949, “Making Your Oscillator Work”
See the notes following
for additional
information.
Osc Type
Crystal
Freq.
Typical Capacitor Values
Tested:
C1
C2
HS
4 MHz
27 pF
27 pF
8 MHz
22 pF
22 pF
20 MHz
15 pF
15 pF
Capacitor values are for design guidance only.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
DD
and temperature range for the application.
Refer to the Microchip application notes cited in
for oscillator-specific information. Also see
the notes following this table for additional
information.
information.
Note 1:
Higher capacitance increases the stability
of the oscillator but also increases the
start-up time.
of the oscillator but also increases the
start-up time.
2:
Since each resonator/crystal has its own
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external
components.
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external
components.
3:
Rs may be required to avoid overdriving
crystals with a low drive level specification.
crystals with a low drive level specification.
4:
Always verify oscillator performance over
the V
the V
DD
and temperature range that is
expected for the application.
Note 1:
See
for initial values of
C1 and C2.
2:
A series resistor (R
S
) may be required for AT
strip cut crystals.
3:
R
F
varies with the oscillator mode chosen.
C1
(1)
C2
(1)
XTAL
OSC2
OSC1
R
F
(3)
Sleep
To
Logic
R
S(2)
Internal
PIC18F87K22