PIC18F6620 Microchip, PIC18F6620 Datasheet - Page 23

• Manufacturer Part Number: PIC18F6620
• Description: Microcontroller
• Manufacturer: Microchip

2.0
2.1
The PIC18FXX20 devices can be operated in eight
different oscillator modes. The user can program three
configuration bits (FOSC2, FOSC1 and FOSC0) to
select one of these eight modes:
1.
2.
3.
4.
5.
6.
7.
8.
2.2
In XT, LP, HS or HS+PLL Oscillator modes, a crystal or
ceramic resonator is connected to the OSC1 and
OSC2 pins to establish oscillation. Figure 2-1 shows
the pin connections.
The PIC18FXX20 oscillator design requires the use of
a parallel cut crystal.
FIGURE 2-1:
 2004 Microchip Technology Inc.
Note:
Note 1: See Table 2-1 and Table 2-2 for recommended
LP
XT
HS
HS+PLL
RC
RCIO
EC
ECIO
C1
C2
2: A series resistor (R
3: R
OSCILLATOR
CONFIGURATIONS
Oscillator Types
Crystal Oscillator/Ceramic
Resonators
(1)
(1)
Use of a series cut crystal may give a fre-
quency out of the crystal manufacturer’s
specifications.
values of C1 and C2.
strip cut crystals.
XTAL
F
R
S
varies with the oscillator mode chosen.
(2)
PIC18F6520/8520/6620/8620/6720/8720
with PLL enabled
enabled
Low-Power Crystal
Crystal/Resonator
High-Speed Crystal/Resonator
High-Speed Crystal/Resonator
External Resistor/Capacitor
External Resistor/Capacitor with
I/O pin enabled
External Clock
External Clock with I/O pin
OSC2
OSC1
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
CONFIGURATION)
S
R
) may be required for AT
F
(3)
PIC18FXX20
Sleep
To
Internal
Logic
TABLE 2-1:
These values are for design guidance only.
See notes following this table.
All resonators used did not have built-in capacitors.
16.0 MHz Murata Erie CSA16.00MX
2.0 MHz Murata Erie CSA2.00MG
4.0 MHz Murata Erie CSA4.00MG
8.0 MHz Murata Erie CSA8.00MT
Mode
Note 1: Higher capacitance increases the stability
HS
XT
2: When operating below 3V V
3: Since each resonator/crystal has its own
of the oscillator, but also increases the
start-up time.
using certain ceramic resonators at any
voltage, it may be necessary to use high
gain HS mode, try a lower frequency
resonator, or switch to a crystal oscillator.
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate
components,
performance.
16.0 MHz
455 kHz
2.0 MHz
4.0 MHz
8.0 MHz
Freq
Resonators Used:
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
Ranges Tested:
68-100 pF
values
15-68 pF
15-68 pF
10-68 pF
10-22 pF
or
C1
verify
DS39609B-page 21
of
DD
68-100 pF
15-68 pF
15-68 pF
10-68 pF
10-22 pF
, or when
oscillator
external
0.5%
0.5%
0.5%
0.5%
C2