PIC18LF452 Microchip Technology, PIC18LF452 Datasheet - Page 19

• Manufacturer Part Number: PIC18LF452
• Description: (PIC18LFxx2) Enhanced FLASH Microcontrollers
• Manufacturer: Microchip Technology

2.0
2.1
The PIC18FXX2 can be operated in eight different
Oscillator modes. The user can program three configu-
ration 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 PIC18FXX2 oscillator design requires the use of a
parallel cut crystal.
FIGURE 2-1:
Note:
2002 Microchip Technology Inc.
Note 1: See
LP
XT
HS
HS + PLL
RC
RCIO
EC
ECIO
C1
C2
OSCILLATOR
CONFIGURATIONS
Oscillator Types
Crystal Oscillator/Ceramic
Resonators
(1)
(1)
2: A series resistor (R
3: R
Use of a series cut crystal may give a fre-
quency out of the crystal manufacturers
specifications.
recommended values of C1 and C2.
AT strip cut crystals.
XTAL
R
F
S
(2)
varies with the Oscillator mode chosen.
Low Power Crystal
Crystal/Resonator
High Speed Crystal/Resonator
High Speed Crystal/Resonator
with PLL enabled
External Resistor/Capacitor
External Resistor/Capacitor with
External Clock
External
enabled
I/O pin enabled
OSC2
OSC1
Table 2-1
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
CONFIGURATION)
Clock
R
S
and
F
) may be required for
(3)
with
Table 2-2
SLEEP
PIC18FXXX
I/O
To
Internal
Logic
for
pin
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
455 kHz Panasonic EFO-A455K04B
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 appro-
priate values of external components, or
verify oscillator 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:
PIC18FXX2
68 - 100 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
C1
DS39564B-page 17
DD
68 - 100 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
, or when
0.3%
0.5%
0.5%
0.5%
0.5%
C2