MCP2515
FIGURE 8-3:
EXTERNAL SERIES RESONANT CRYSTAL OSCILLATOR CIRCUIT(1)
To Other
Devices
330 kΩ
330 kΩ
74AS04
74AS04
74AS04
MCP2510
OSC1
0.1 mF
XTAL
Note 1: Duty cycle restrictions must be observed (see Table 12-2).
TABLE 8-1:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
TABLE 8-2:
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Typical Capacitor Values Used:
Typical Capacitor
Values Tested:
Osc
Crystal
Freq.(2)
Type(1)(4)
Mode
Freq.
OSC1
OSC2
C1
C2
HS
8.0 MHz
27 pF
22 pF
27 pF
22 pF
HS
4 MHz
8 MHz
20 MHz
27 pF
22 pF
15 pF
27 pF
22 pF
15 pF
16.0 MHz
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.
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.
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 infor-
mation.
See the notes following this Table for additional
information.
Resonators Used:
4.0 MHz
Crystals Used(3)
:
8.0 MHz
4.0 MHz
8.0 MHz
20.0 MHz
16.0 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.
DS21801D-page 54
Preliminary
© 2005 Microchip Technology Inc.