PIC18C242 MICROCHIP [Microchip Technology], PIC18C242 Datasheet - Page 16

• Manufacturer Part Number: PIC18C242
• Description: High-Performance Microcontrollers with 10-Bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18CXX2
TABLE 2-1:
TABLE 2-2:
DS39026B-page 16
Ranges Tested:
Mode
XT
HS
Resonators Used:
455 kHz
2.0 MHz
4.0 MHz
8.0 MHz
16.0 MHz
Osc Type
32.0 kHz
200 kHz
1.0 MHz
4.0 MHz
8.0 MHz
20.0 MHz
Note 1: Recommended values of C1 and C2 are
All resonators used did not have built-in capacitors.
HS
LP
XT
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
These values are for design guidance only. See
notes at bottom of page.
These values are for design guidance only. See
notes at bottom of page.
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 appropri-
ate values of external components.
XT mode, to avoid overdriving crystals with
low drive level specification.
Freq
455 kHz
2.0 MHz
4.0 MHz
8.0 MHz
16.0 MHz
Panasonic EFO-A455K04B
Murata Erie CSA2.00MG
Murata Erie CSA4.00MG
Murata Erie CSA8.00MT
Murata Erie CSA16.00MX
Crystal
Freq
Epson C-001R32.768K-A
STD XTL 200.000KHz
ECS ECS-10-13-1
ECS ECS-40-20-1
EPSON CA-301 8.000M-C
EPSON CA-301 20.000M-C
20.0 MHz
25.0 MHz
32.0 kHz
200 kHz
200 kHz
1.0 MHz
4.0 MHz
4.0 MHz
8.0 MHz
CERAMIC RESONATORS
CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Crystals Used
Cap. Range
C1
OSC1
68 - 100 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
47-68 pF
15-33 pF
15-33 pF
33 pF
15 pF
15 pF
15 pF
15 pF
TBD
Cap.
Range
C2
OSC2
68 - 100 pF
15 - 68 pF
15 - 68 pF
10 - 68 pF
10 - 22 pF
± 20 PPM
± 20 PPM
± 50 PPM
± 50 PPM
± 30 PPM
± 30 PPM
47-68 pF
15-33 pF
15-33 pF
0.3%
0.5%
0.5%
0.5%
0.5%
33 pF
15 pF
15 pF
15 pF
15 pF
TBD
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,
especially for low C
take 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).
2.4
The EC and ECIO oscillator modes require an external
clock source to be connected to the OSC1 pin. The
feedback device between OSC1 and OSC2 is turned
off in these modes to save current. There is no oscilla-
tor startup time required after a Power-On-Reset or
after a recovery from SLEEP mode.
In the EC 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 2-4 shows the pin connections for the EC
oscillator mode.
C
V
Recommended values:
R
EXT
SS
EXT
V
DD
RC Oscillator
External Clock Input
F
OSC
RC OSCILLATOR MODE
EXT
/4
OSC1
OSC2/CLKO
EXT
values. The user also needs to
3 k
C
EXT
7/99 Microchip Technology Inc.
) and capacitor (C
> 20pF
R
EXT
100 k
PIC18CXXX
Internal
clock
EXT
) val-