PIC16C63A/65B/73B/74B
13.2
13.2.1
Oscillator Configurations
OSCILLATOR TYPES
FIGURE 13-1:
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
CRYSTAL/CERAMIC
RESONATOR OPERATION
(HS, XT OR LP
OSC CONFIGURATION)
OSC1
To internal
logic
SLEEP
PIC16CXX
C1
XTAL
OSC2
RS
C2
(Note 1)
R
F
13.2.2
CRYSTAL OSCILLATOR/CERAMIC
RESONATORS
See Table 13-1 and Table 13-2 for recommended values of C1
and C2.
Note 1:
A series resistor may be required for AT strip cut crystals.
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 13-1). 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 13-2). See the PICmicro™ Mid-
Range MCU Reference Manual (DS33023) for details
on building an external oscillator.
FIGURE 13-2:
EXTERNAL CLOCK INPUT
OPERATION (HS, XT OR
LP OSC CONFIGURATION)
OSC1
PIC16CXX
Clock from
ext. system
Open
OSC2
DS30605C-page 86
2000 Microchip Technology Inc.
MICROCHIP [ MICROCHIP TECHNOLOGY ]
