PIC16C71T-04/SP View Datasheet(PDF) - Microchip Technology
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PIC16C71T-04/SP Datasheet PDF : 176 Pages
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8.2 Oscillator Configurations
8.2.1 OSCILLATOR TYPES
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:
• LP
• XT
• HS
• RC
Low Power Crystal
Crystal/Resonator
High Speed Crystal/Resonator
Resistor/Capacitor
8.2.2 CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
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).
FIGURE 8-4:
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
OSC CONFIGURATION)
OSC1
C1
XTAL
RF
OSC2
SLEEP
PIC16CXXX
RS
C2 Note1
(2)
To internal
logic
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)
Clock from
ext. system
Open
OSC1
PIC16CXXX
OSC2
PIC16C71X
TABLE 8-1: CERAMIC RESONATORS,
PIC16C71
Ranges Tested:
Mode
Freq
OSC1
OSC2
XT
455 kHz
47 - 100 pF 47 - 100 pF
2.0 MHz
15 - 68 pF 15 - 68 pF
4.0 MHz
15 - 68 pF 15 - 68 pF
HS
8.0 MHz
15 - 68 pF 15 - 68 pF
16.0 MHz 10 - 47 pF 10 - 47 pF
These values are for design guidance only. See
notes at bottom of page.
Resonators Used:
455 kHz Panasonic EFO-A455K04B ± 0.3%
2.0 MHz Murata Erie CSA2.00MG ± 0.5%
4.0 MHz Murata Erie CSA4.00MG ± 0.5%
8.0 MHz Murata Erie CSA8.00MT ± 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
Mode
Freq
OSC1
OSC2
LP
32 kHz 33 - 68 pF 33 - 68 pF
200 kHz 15 - 47 pF 15 - 47 pF
XT
100 kHz 47 - 100 pF 47 - 100 pF
500 kHz 20 - 68 pF 20 - 68 pF
1 MHz
15 - 68 pF 15 - 68 pF
2 MHz
15 - 47 pF 15 - 47 pF
4 MHz
15 - 33 pF 15 - 33 pF
HS
8 MHz
15 - 47 pF 15 - 47 pF
20 MHz 15 - 47 pF 15 - 47 pF
These values are for design guidance only. See
notes at bottom of page.
© 1997 Microchip Technology Inc.
DS30272A-page 49
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