PIC16F716-I Datasheet, PDF (65/136 Pages) Microchip Technology – 8-bit Flash-based Microcontroller with A/D Converter and Enhanced Capture/Compare/PWM

9.2 Oscillator Configurations
9.2.1 OSCILLATOR TYPES
The PIC16F716 can be operated in four different
oscillator modes. The user can program two Configura-
tion 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
9.2.2
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 9-1). The
PIC16F716 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/CLKIN pin (Figure 9-2).
FIGURE 9-1:
C1⁽¹⁾
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
OSC CONFIGURATION)
OSC1
XTAL
OSC2
RS⁽²⁾
C2⁽¹⁾
RF⁽³⁾
To
internal
logic
Sleep
PIC16F716
Note 1:
2:
3:
See Table 9-1 and Table 9-2 for
recommended values of C1 and C2.
A series resistor (RS) may be required.
RF varies with the crystal chosen.
FIGURE 9-2:
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR
LP OSC
CONFIGURATION)
Clock from
ext. system
Open
OSC1
PIC16F716
OSC2
PIC16F716
TABLE 9-1: CERAMIC RESONATORS
Ranges Tested:
Mode
XT
HS
Note 1:
Freq
OSC1 (C1) OSC2 (C2)
455 kHz
2.0 MHz
68-100 pF 68-100 pF
15-68 pF 15-68 pF
4.0 MHz
8.0 MHz
16.0 MHz
10-68 pF
15-68 pF
10-22 pF
10-68 pF
15-68 pF
10-22 pF
These values are for design guidance
only. See notes at bottom of page.
TABLE 9-2: CAPACITOR SELECTION FOR
CRYSTAL OSCILLATOR
Osc Type
Crystal
Freq
Cap. Range Cap. Range
C1
C2
LP
XT
HS
Note 1:
32 kHz
15-33 pF
15-33 pF
200 kHz
5-10 pF
5-10 pF
200 kHz
47-68 pF
47-68 pF
1 MHz
15-33 pF
15-33 pF
4 MHz
15-33 pF
15-33 pF
4 MHz
15-33 pF
15-33 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.
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
characteristics, the user should consult
the resonator/crystal manufacturer for
appropriate values of external
components.
3: RS may be required to avoid overdriving
crystals with low drive level specification.
4: When using an external clock for the
OSC1 input, loading of the OSC2 pin
must be kept to a minimum by leaving the
OSC2 pin unconnected.
© 2007 Microchip Technology Inc.
DS41206B-page 63