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PIC16F87XATI/SP Datasheet - Page 145

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14.2
Oscillator Configurations
14.2.1
OSCILLATOR TYPES
The PIC16F87XA can be operated in four different
oscillator modes. The user can program two configura-
tion bits (F
1 and F
0) to select one of these four
OSC
OSC
modes:
• LP
Low-Power Crystal
• XT
Crystal/Resonator
• HS
High-Speed Crystal/Resonator
• RC
Resistor/Capacitor
14.2.2
CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1/CLKI and OSC2/CLKO pins
to establish oscillation (Figure 14-1). The PIC16F87XA
oscillator design requires the use of a parallel cut crys-
tal. Use of a series cut crystal may give a frequency out
of the crystal manufacturer’s specifications. When in
XT, LP or HS modes, the device can have an external
clock source to drive the OSC1/CLKI pin (Figure 14-2).
FIGURE 14-1:
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
OSC CONFIGURATION)
(1)
C1
OSC1
XTAL
(3)
RF
OSC2
(2)
R
s
(1)
PIC16F87XA
C2
Note 1: See Table 14-1 and Table 14-2 for recommended
values of C1 and C2.
2: A series resistor (R
) may be required for AT
s
strip cut crystals.
3: RF varies with the crystal chosen.
 2001-2013 Microchip Technology Inc.
FIGURE 14-2:
Clock from
Ext. System
TABLE 14-1:
Mode
XT
HS
16.0 MHz
These values are for design guidance only.
See notes following Table 14-2.
2.0 MHz
Murata Erie CSA2.00MG
4.0 MHz
Murata Erie CSA4.00MG
8.0 MHz
To
16.0 MHz
Murata Erie CSA16.00MX
Internal
All resonators used did not have built-in capacitors.
Logic
Sleep
PIC16F87XA
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR
LP OSC CONFIGURATION)
OSC1
PIC16F87XA
OSC2
Open
CERAMIC RESONATORS
Ranges Tested:
Freq.
OSC1
OSC2
455 kHz
68-100 pF
68-100 pF
2.0 MHz
15-68 pF
15-68 pF
4.0 MHz
15-68 pF
15-68 pF
8.0 MHz
10-68 pF
10-68 pF
10-22 pF
10-22 pF
Resonators Used:
 0.5%
 0.5%
 0.5%
Murata Erie CSA8.00MT
 0.5%
DS39582C-page 145

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