PIC16C71X
8.2
Oscillator Configurations
TABLE 8-1:
CERAMIC RESONATORS,
PIC16C71
8.2.1
OSCILLATOR TYPES
Ranges Tested:
The PIC16CXX can be operated in four different oscil-
lator modes. The user can program two configuration
bits (FOSC1 and FOSC0) to select one of these four
modes:
Mode
XT
Freq
OSC1
OSC2
455 kHz
2.0 MHz
4.0 MHz
47 - 100 pF 47 - 100 pF
15 - 68 pF 15 - 68 pF
15 - 68 pF 15 - 68 pF
• LP
• XT
• HS
• RC
Low Power Crystal
Crystal/Resonator
HS
8.0 MHz
15 - 68 pF 15 - 68 pF
10 - 47 pF 10 - 47 pF
16.0 MHz
High Speed Crystal/Resonator
Resistor/Capacitor
These values are for design guidance only. See
notes at bottom of page.
8.2.2
CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
Resonators Used:
455 kHz
Panasonic EFO-A455K04B ± 0.3%
In XT, LP or HS modes a crystal or ceramic resonator
is connected to the OSC1/CLKIN and OSC2/CLKOUT
pins to establish oscillation (Figure 8-4). The
PIC16CXX Oscillator design requires the use of a par-
allel cut crystal. Use of a series cut crystal may give a
frequency out of the crystal manufacturers specifica-
tions. When in XT, LP or HS modes, the device can
have an external clock source to drive the OSC1/
CLKIN pin (Figure 8-5).
2.0 MHz Murata Erie CSA2.00MG
4.0 MHz Murata Erie CSA4.00MG
8.0 MHz Murata Erie CSA8.00MT
± 0.5%
± 0.5%
± 0.5%
16.0 MHz Murata Erie CSA16.00MX ± 0.5%
All resonators used did not have built-in capacitors.
TABLE 8-2:
CAPACITOR SELECTION
FOR CRYSTAL OSCILLATOR,
PIC16C71
FIGURE 8-4: CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
Mode
Freq
OSC1
OSC2
LP
32 kHz
200 kHz
33 - 68 pF
15 - 47 pF
33 - 68 pF
15 - 47 pF
OSC CONFIGURATION)
XT
100 kHz
500 kHz
1 MHz
2 MHz
4 MHz
47 - 100 pF
20 - 68 pF
15 - 68 pF
15 - 47 pF
15 - 33 pF
47 - 100 pF
20 - 68 pF
15 - 68 pF
15 - 47 pF
15 - 33 pF
OSC1
C1
XTAL
OSC2
SLEEP
PIC16CXXX
RF
HS
8 MHz
20 MHz
15 - 47 pF
15 - 47 pF
15 - 47 pF
15 - 47 pF
To internal
logic
RS
(2)
C2
Note1
These values are for design guidance only. See
notes at bottom of page.
See Table 8-1 and Table 8-1 for recommended values of
C1 and C2.
Note 1: A series resistor may be required for AT strip
cut crystals.
2: The buffer is on the OSC2 pin.
FIGURE 8-5: EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
OSC1
OSC2
Clock from
ext. system
PIC16CXXX
Open
1997 Microchip Technology Inc.
DS30272A-page 49
MICROCHIP [ MICROCHIP ]
