Datasheet

PIC16C62B/72A
DS35008C-page 56 Preliminary  1998-2013 Microchip Technology Inc.
10.2 Oscillator Configurations
10.2.1 OSCILLATOR TYPES
The PIC16CXXX 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 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/CLKIN and OSC2/CLKOUT
pins to establish oscillation (Figure 10-2). The
PIC16CXXX 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 use
an external clock source to drive the OSC1/CLKIN pin
(Figure 10-3).
FIGURE 10-2: CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
OSC CONFIGURATION)
FIGURE 10-3: EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR LP
OSC CONFIGURATION)
TABLE 10-1 CERAMIC RESONATORS
TABLE 10-2 CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Note1: See Table 10-1 and Table 10-2 for recom-
mended values of C1 and C2.
2: A series resistor (RS) may be required for
AT strip cut crystals.
3: RF varies with the crystal chosen.
C1
(1)
C2
(1)
XTAL
OSC2
OSC1
RF
(3)
SLEEP
To
logic
PIC16CXXX
RS
(2)
internal
OSC1
OSC2
Open
Clock from
ext. system
PIC16CXXX
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.
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%
Resonators did not have built-in capacitors.
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.
Crystals Used
32 kHz Epson C-001R32.768K-A ± 20 PPM
200 kHz STD XTL 200.000KHz ± 20 PPM
1 MHz ECS ECS-10-13-1 ± 50 PPM
4 MHz ECS ECS-40-20-1 ± 50 PPM
8 MHz EPSON CA-301 8.000M-C ± 30 PPM
20 MHz EPSON CA-301 20.000M-C ± 30 PPM
Note 1: Higher capacitance increases the stability of the
oscillator, but also increases the start-up time.
2: Since each resonator/crystal has its own charac-
teristics, the user should consult the resona-
tor/crystal manufacturer for appropriate values of
external components.
3: Rs may be required in HS mode, as well as XT
mode, to avoid overdriving crystals with low drive
level specification.
4: Oscillator performance should be verified when
migrating between devices (including
PIC16C62A to PIC16C62B and PIC16C72 to
PIC16C72A)