PIC18F258 Datasheet, PDF (19/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN

2.0 OSCILLATOR
CONFIGURATIONS
2.1 Oscillator Types
The PIC18FXX8 can be operated in one of eight Oscil-
lator modes, programmable by three configuration bits
(FOSC2, FOSC1, and FOSC0).
1. LP
2. XT
3. HS
4. HS4
5. RC
6. RCIO
7. EC
8. ECIO
Low Power Crystal
Crystal/Resonator
High Speed Crystal/Resonator
High Speed Crystal/Resonator with
PLL enabled
External Resistor/Capacitor
External Resistor/Capacitor with I/O
pin enabled
External Clock
External Clock with I/O pin enabled
2.2 Crystal Oscillator/Ceramic
Resonators
In XT, LP, HS or HS4 (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. An external clock source may also
be connected to the OSC1 pin, as shown in Figure 2-3
and Figure 2-4.
The PIC18FXX8 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 manufacturer’s
specifications.
PIC18FXX8
FIGURE 2-1:
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP OSC
CONFIGURATION)
C1⁽¹⁾
OSC1
XTAL
RF⁽³⁾
To
Internal
Logic
RS⁽²⁾
C2⁽¹⁾
OSC2
SLEEP
PIC18FXX8
Note 1: See Table 2-1 and Table 2-2 for recommended
values of C1 and C2.
2: A series resistor (RS) may be required for AT
strip cut crystals.
3: RF varies with the crystal chosen.
TABLE 2-1: CERAMIC RESONATORS
Ranges Tested:
Mode
Freq
OSC1
OSC2
XT
455 kHz 68 - 100 pF 68 - 100 pF
2.0 MHz
4.0 MHz
15 - 68 pF 15 - 68 pF
15 - 68 pF 15 - 68 pF
HS
8.0 MHz 10 - 68 pF 10 - 68 pF
16.0 MHz
20.0 MHz
10 - 22 pF
TBD
10 - 22 pF
TBD
25.0 MHz
TBD
TBD
HS+PLL 4.0 MHz
TBD
TBD
8.0 MHz
10.0 MHz
10 - 68 pF
TBD
10 - 68 pF
TBD
These values are for design guidance only.
See notes following Table 2-2.
Resonators Used:
455 kHz Panasonic EFO-A455K04B ± 0.3%
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.
 2002 Microchip Technology Inc.
Preliminary
DS41159B-page 17