PIC16F72X/PIC16LF72X
Clock source modes are configured by the FOSC bits
in Configuration Word 1 (CONFIG1). The oscillator
module can be configured for one of eight modes of
operation.
7.0
7.1
OSCILLATOR MODULE
Overview
The oscillator module has a wide variety of clock sources
and selection features that allow it to be used in a wide
range of applications while maximizing performance and
minimizing power consumption. Figure 7-1 illustrates a
block diagram of the oscillator module.
1. RC – External Resistor-Capacitor (RC) with
FOSC/4 output on OSC2/CLKOUT.
2. RCIO – External Resistor-Capacitor (RC) with
I/O on OSC2/CLKOUT.
3. INTOSC – Internal oscillator with FOSC/4 output
on OSC2 and I/O on OSC1/CLKIN.
Clock sources can be configured from external
oscillators, quartz crystal resonators, ceramic resonators
and Resistor-Capacitor (RC) circuits. In addition, the
system can be configured to use an internal calibrated
high-frequency oscillator as clock source, with a choice
of selectable speeds via software.
4. INTOSCIO – Internal oscillator with I/O on
OSC1/CLKIN and OSC2/CLKOUT.
5. EC – External clock with I/O on OSC2/CLKOUT.
6. HS – High Gain Crystal or Ceramic Resonator
mode.
7. XT
– Medium Gain Crystal or Ceramic
Resonator Oscillator mode.
8. LP – Low-Power Crystal mode.
FIGURE 7-1:
SIMPLIFIED PIC® MCU CLOCK SOURCE BLOCK DIAGRAM
FOSC<2:0>
(Configuration Word 1)
External Oscillator
OSC2
OSC1
Sleep
LP, XT, HS, RC, EC
System Clock
(CPU and Peripherals)
Internal Oscillator
500 kHz
IRCF<1:0>
(OSCCON Register)
INTOSC
0
1
16 MHz/500 kHz
11
10
01
00
32x
PLL
8 MHz/250 kHz
4 MHz/125 kHz
2 MHz/62.5 kHz
PLLEN
(Configuration Word 1)
© 2009 Microchip Technology Inc.
DS41341E-page 89
MICROCHIP [ MICROCHIP ]
