PIC18LF452 Microchip Technology, PIC18LF452 Datasheet - Page 20

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

PIC18FXX2
TABLE 2-2:
An external clock source may also be connected to the
OSC1 pin in the HS, XT and LP modes, as shown in
Figure 2-2.
FIGURE 2-2:
DS39564B-page 18
These values are for design guidance only.
See notes following this table.
20.0 MHz
32.0 kHz
200 kHz
1.0 MHz
4.0 MHz
8.0 MHz
Note 1: Higher capacitance increases the stability
Clock from
Ext. System
Mode
HS
LP
XT
2: Rs may be required in HS mode, as well
3: Since each resonator/crystal has its own
of the oscillator, but also increases the
start-up time.
as XT mode, to avoid overdriving crystals
with low drive level specification.
characteristics, the user should consult the
resonator/crystal manufacturer for appro-
priate values of external components., or
verify oscillator performance.
20.0 MHz
25.0 MHz
Epson CA-301 20.000M-C ± 30 PPM
Open
32.0 kHz
1.0 MHz
4.0 MHz
4.0 MHz
8.0 MHz
Epson C-001R32.768K-A
200 kHz
200 kHz
Epson CA-301 8.000M-C
STD XTL 200.000KHz
Freq
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
ECS ECS-10-13-1
ECS ECS-40-20-1
Ranges Tested:
Crystals Used
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
OSC1
OSC2
22-68 pF
15-33 pF
15-33 pF
15-33 pF
33 pF
15 pF
15 pF
15 pF
15 pF
C1
PIC18FXXX
± 20 PPM
± 20 PPM
± 30 PPM
± 50 PPM
± 50 PPM
22-68 pF
15-33 pF
15-33 pF
15-33 pF
33 pF
15 pF
15 pF
15 pF
15 pF
C2
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 2-3 shows how the
R/C 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 2-3:
The RCIO Oscillator mode functions like the RC mode,
except that the OSC2 pin becomes an additional gen-
eral purpose I/O pin. The I/O pin becomes bit 6 of
PORTA (RA6).
C
V
Recommended values:3 k
Note:
R
EXT
SS
EXT
V
DD
RC Oscillator
If the oscillator frequency divided by 4 sig-
nal is not required in the application, it is
recommended to use RCIO mode to save
current.
EXT
F
OSC
values. The user also needs to take
/4
RC OSCILLATOR MODE
OSC1
C
OSC2/CLKO
EXT
EXT
2002 Microchip Technology Inc.
) and capacitor (C
> 20pF
R
EXT
100 k
PIC18FXXX
Internal
Clock
EXT
) val-