PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 20

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18FXX8
TABLE 2-2:
DS41159B-page 18
LP
XT
HS
HS+PLL
These values are for design guidance only.
See notes on this page.
Note 1: Recommended values of C1 and C2 are
Osc Type
20.0 MHz
32.0 kHz
1.0 MHz
4.0 MHz
8.0 MHz
200 kHz
2: Higher capacitance increases the stability
3: Since each resonator/crystal has its own
4: Rs may be required in HS mode, as well as
identical to the ranges tested (Table 2-1).
of the oscillator, but also increases the
start-up time.
characteristics, the user should consult the
resonator/crystal manufacturer for
appropriate values of external components.
XT mode, to avoid overdriving crystals with
low drive level specification.
EPSON CA-301 8.000M-C
Epson C-001R32.768K-A
EPSON CA-301 20.000M-
20.0 MHz
25.0 MHz
10.0 MHz
32.0 kHz
200 kHz
200 kHz
1.0 MHz
4.0 MHz
4.0 MHz
8.0 MHz
4.0 MHz
8.0 MHz
Crystal
STD XTL 200.000KHz
Freq
ECS ECS-10-13-1
ECS ECS-40-20-1
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Crystals Used
C
Cap. Range
15-33 pF
15-33 pF
47-68 pF
15-33 pF
33 pF
15 pF
15 pF
15 pF
15 pF
15 pF
TBD
TBD
C1
Cap. Range
± 20 PPM
± 20 PPM
± 50 PPM
± 50 PPM
± 30 PPM
± 30 PPM
47-68 pF
15-33 pF
15-33 pF
15-33 pF
33 pF
15 pF
15 pF
15 pF
15 pF
15 pF
TBD
TBD
C2
Preliminary
2.3
For timing insensitive applications, the “RC” and
"RCIO" device options offer additional cost savings.
The RC oscillator frequency is a function of the supply
voltage, the resistor (R
ues and the operating temperature. In addition to this,
the oscillator frequency will vary from unit to unit due to
normal process parameter variation. Furthermore, the
difference in lead frame capacitance between package
types will also affect the oscillation frequency, espe-
cially for low C
into account variation due to tolerance of external R
and C components used. Figure 2-2 shows how the RC
combination is connected.
In the RC Oscillator mode, the oscillator frequency
divided by 4 is available on the OSC2 pin. This signal
may be used for test purposes or to synchronize other
logic.
FIGURE 2-2:
The RCIO Oscillator mode functions like the RC mode,
except that the OSC2 pin becomes an additional
general purpose I/O pin.
C
V
Recommended values:
R
EXT
SS
EXT
V
DD
RC Oscillator
F
EXT
OSC
/4
values. The user also needs to take
RC OSCILLATOR MODE
OSC1
OSC2/CLKO
EXT
 2002 Microchip Technology Inc.
3 k Ω ≤ R
C
EXT
) and capacitor (C
> 20 pF
PIC18FXX8
EXT
≤ 100 k Ω
Internal
Clock
EXT
) val-