PIC18F2423 MICROCHIP [Microchip Technology], PIC18F2423 Datasheet - Page 25

• Manufacturer Part Number: PIC18F2423
• Description: 28/40/44-Pin, Enhanced Flash Microcontrollers with 12-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

2.0
2.1
PIC18LF2423/2523/4423/4523 devices can be oper-
ated in ten different oscillator modes. The user can pro-
gram the Configuration bits, FOSC3:FOSC0, in
Configuration Register 1H to select one of these ten
modes:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. ECIO
2.2
In XT, LP, HS or HSPLL 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 oscillator design requires the use of a parallel cut
crystal.
© 2007 Microchip Technology Inc.
Note:
LP
XT
HS
HSPLL High-Speed Crystal/Resonator
RC
RCIO
INTIO1 Internal Oscillator with F
INTIO2 Internal Oscillator with I/O on RA6
EC
OSCILLATOR
CONFIGURATIONS
Oscillator Types
Crystal Oscillator/Ceramic
Resonators
Use of a series cut crystal may give a fre-
quency out of the crystal manufacturer’s
specifications.
Low-Power Crystal
Crystal/Resonator
High-Speed Crystal/Resonator
with PLL Enabled
External Resistor/Capacitor with
F
External Resistor/Capacitor with I/O
on RA6
on RA6 and I/O on RA7
and RA7
External Clock with F
External Clock with I/O on RA6
OSC
/4 Output on RA6
OSC
OSC
/4 Output
/4 Output
PIC18F2423/2523/4423/4523
Preliminary
FIGURE 2-1:
TABLE 2-1:
Capacitor values are for design guidance only.
Different capacitor values may be required to produce
acceptable oscillator operation. The user should test
the performance of the oscillator over the expected
V
See the notes following Table 2-2 for additional
information.
Note 1: See Table 2-1 and Table 2-2 for initial values of
DD
Note:
Mode
XT
and temperature range for the application.
C1
C2
2: A series resistor (R
3: R
(1)
(1)
Typical Capacitor Values Used:
C1 and C2.
strip cut crystals.
When using resonators with frequencies
above 3.6 MHz, the use of HS mode,
rather than XT mode, is recommended.
HS mode may be used at any V
which the controller is rated. If HS is
selected, it is possible that the gain of the
oscillator will overdrive the resonator.
Therefore, a series resistor should be
placed between the OSC2 pin and the
resonator. As a good starting point, the
recommended value of R
F
3.58 MHz
XTAL
varies with the oscillator mode chosen.
R
Freq.
S (2)
CAPACITOR SELECTION FOR
CERAMIC RESONATORS
OSC2
OSC1
CRYSTAL/CERAMIC
RESONATOR OPERATION
(XT, LP, HS OR HSPLL
CONFIGURATION)
S
) may be required for AT
OSC1
15 pF
R
F
PIC18FXXXX
(3)
DS39755B-page 23
S
is 330Ω.
Sleep
To
OSC2
15 pF
Internal
Logic
DD
for