PIC18F6X2X Datasheet, PDF (23/386 Pages) Microchip Technology – 64/80-Pin High Performance, 64-Kbyte Enhanced FLASH Microcontrollers with A/D

2.0 OSCILLATOR
CONFIGURATIONS
2.1 Oscillator Types
The PIC18F6X2X/8X2X devices can be operated in
twelve different Oscillator modes. The user can pro-
gram four configuration bits (FOSC3, FOSC2, FOSC1,
and FOSC0) to select one of these eight modes:
1. LP
Low Power Crystal
2. XT
Crystal/Resonator
3. HS
High Speed Crystal/Resonator
4. RC
External Resistor/Capacitor
5. EC
External Clock
6. ECIO
External Clock with I/O pin
enabled
7. HS+PLL
High Speed Crystal/Resonator
with PLL enabled
8. RCIO
External Resistor/Capacitor with
I/O pin enabled
9. ECIO+SPLL External Clock with software
controlled PLL
10. ECIO+PLL External Clock with PLL and I/O
pin enabled
11. HS+SPLL High Speed Crystal/Resonator
with software control
12. RCIO
External Resistor/Capacitor with
I/O pin enabled
2.2 Crystal Oscillator/Ceramic
Resonators
In XT, LP, HS, HS+PLL or HS+SPLL 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 PIC18F6X2X/8X2X oscillator design requires the
use of a parallel cut crystal.
Note:
Use of a series cut crystal may give a fre-
quency out of the crystal manufacturers
specifications.
PIC18F6X2X/8X2X
FIGURE 2-1:
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
CONFIGURATION)
C1⁽¹⁾
OSC1
XTAL
RF⁽³⁾
To
Internal
Logic
RS⁽²⁾
C2⁽¹⁾
OSC2
SLEEP
PIC18F6X2X/8X2X
Note 1:
2:
3:
See Table 2-1 and Table 2-2 for
recommended values of C1 and C2.
A series resistor (RS) may be required for
AT strip cut crystals.
RF varies with the Oscillator mode chosen.
TABLE 2-1: CAPACITOR SELECTION FOR
CERAMIC RESONATORS
Ranges Tested:
Mode
Freq
C1
C2
XT
455 kHz 68 - 100 pF 68 - 100 pF
2.0 MHz 15 - 68 pF 15 - 68 pF
4.0 MHz 15 - 68 pF 15 - 68 pF
HS
8.0 MHz 10 - 68 pF 10 - 68 pF
16.0 MHz 10 - 22 pF 10 - 22 pF
These values are for design guidance only.
See notes following this table.
Resonators Used:
2.0 MHz Murata Erie CSA2.00MG
± 0.5%
4.0 MHz Murata Erie CSA4.00MG
± 0.5%
8.0 MHz Murata Erie CSA8.00MT
± 0.5%
16.0 MHz Murata Erie CSA16.00MX
± 0.5%
All resonators used did not have built-in capacitors.
Note 1: Higher capacitance increases the stability
of the oscillator but also increases the
start-up time.
2: When operating below 3V VDD, or when
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.
3: Since each resonator/crystal has its own
characteristics, the user should consult the
resonator/crystal manufacturer for appro-
priate values of external components, or
verify oscillator performance.
 2003 Microchip Technology Inc.
Advance Information
DS39612A-page 21