
MCP2515
DS21801F-page 54
2010 Microchip Technology Inc.
FIGURE 8-3:
EXTERNAL SERIES RESONANT CRYSTAL OSCILLATOR CIRCUIT(1)
TABLE 8-1:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
TABLE 8-2:
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
330 k
Ω
74AS04
MCP2510
OSC1
To Other
Devices
XTAL
330 k
Ω
74AS04
0.1 mF
Note 1: Duty cycle restrictions must be observed (see
Table 12-1). Typical Capacitor Values Used:
Mode
Freq.
OSC1
OSC2
HS
8.0 MHz
27 pF
16.0 MHz
22 pF
Capacitor values are for design guidance only:
These capacitors were tested with the resonators
listed below for basic start-up and operation. These
values are not optimized.
Different capacitor values may be required to
produce acceptable oscillator operation. The user
should test the performance of the oscillator over the
expected VDD and temperature range for the
application.
See the notes following
Table 8-2 for additional
information.
Resonators Used:
4.0 MHz
8.0 MHz
16.0 MHz
Osc
Type(1)(4)
Crystal
Freq.(2)
Typical Capacitor
Values Tested:
C1
C2
HS
4 MHz
27 pF
8 MHz
22 pF
20 MHz
15pF
Capacitor values are for design guidance only:
These capacitors were tested with the crystals listed
below for basic start-up and operation. These values
are not optimized.
Different capacitor values may be required to
produce acceptable oscillator operation. The user
should test the performance of the oscillator over the
expected VDD and temperature range for the
application.
See the notes following this Table for additional
information.
Crystals Used(3):
4.0 MHz
8.0 MHz
20.0 MHz
Note 1:
While higher capacitance increases the
stability of the oscillator, it 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.
3:
RS may be required to avoid overdriving
crystals with low drive level specification.
4:
Always verify oscillator performance over
the VDD and temperature range that is
expected for the application.