Datasheet

 1998-2013 Microchip Technology Inc. DS40182D-page 51
PIC16CE62X
10.2 Oscillator Configurations
10.2.1 OSCILLATOR TYPES
The PIC16CE62X can be operated in four different
oscillator options. The user can program two
configuration bits (FOSC1 and FOSC0) to select one of
these four modes:
• LP Low Power Crystal
• XT Crystal/Resonator
• HS High Speed Crystal/Resonator
• RC Resistor/Capacitor
10.2.2 CRYSTAL OSCILLATOR / CERAMIC
RESONATORS
In XT, LP or HS modes, a crystal or ceramic resonator
is connected to the OSC1 and OSC2 pins to establish
oscillation (Figure 10-1). The PIC16CE62X oscillator
design requires the use of a parallel cut crystal. Use of
a series cut crystal may give a frequency out of the
crystal manufacturers specifications. When in XT, LP or
HS modes, the device can have an external clock
source to drive the OSC1 pin (Figure 10-2).
FIGURE 10-1: CRYSTAL OPERATION
(OR CERAMIC RESONATOR)
(HS, XT OR LP OSC
CONFIGURATION)
FIGURE 10-2: EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
See Table 10-1 and Table 10-2 for recommended values
of C1 and C2.
Note: A series resistor may be required for AT
strip cut crystals.
C1
C2
XTAL
OSC2
RS
OSC1
RF
SLEEP
To Internal Logic
PIC16CE62X
see Note
Clock From
ext. system
PIC16CE62X
OSC1
OSC2
Open
TABLE 10-1: CERAMIC RESONATORS,
PIC16CE62X
TABLE 10-2: CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR,
PIC16CE62X
1. Recommended values of C1 and C2 are identical to
the ranges tested table.
2. Higher capacitance increases the stability of oscillator,
but also increases the start-up time.
3. Since each resonator/crystal has its own characteris-
tics, the user should consult the resonator/crystal
manufacturer for appropriate values of external com-
ponents.
4. Rs may be required in HS mode, as well as XT mode,
to avoid overdriving crystals with low drive level spec-
ification.
Ranges Tested:
Mode Freq OSC1 OSC2
XT 455 kHz
2.0 MHz
4.0 MHz
68 - 100 pF
15 - 68 pF
15 - 68 pF
68 - 100 pF
15 - 68 pF
15 - 68 pF
HS 8.0 MHz
16.0 MHz
10 - 68 pF
10 - 22 pF
10 - 68 pF
10 - 22 pF
These values are for design guidance only. See notes at
bottom of page.
Osc Type
Crystal
Freq
Cap. Range
C1
Cap. Range
C2
LP 32 kHz 33 pF 33 pF
200 kHz 15 pF 15 pF
XT 200 kHz 47-68 pF 47-68 pF
1 MHz 15 pF 15 pF
4 MHz 15 pF 15 pF
HS 4 MHz 15 pF 15 pF
8 MHz 15-33 pF 15-33 pF
20 MHz 15-33 pF 15-33 pF
These values are for design guidance only. See notes at
bottom of page.