PIC16F720_13 Datasheet, PDF (65/254 Pages) Microchip Technology – 20-Pin Flash Microcontrollers

PIC16(L)F720/721
7.0 OSCILLATOR MODULE
7.1 Overview
The oscillator module has a variety of clock sources and
selection features that allow it to be used in a range of
applications while maximizing performance and
minimizing power consumption. Figure 7-1 illustrates a
block diagram of the oscillator module.
The system can be configured to use an internal
calibrated high-frequency oscillator as clock source, with
a choice of selectable speeds via software. In addition,
the system can also be configured to use an external
clock source via the CLKIN pin.
Clock source modes are configured by the FOSC bits
in Configuration Word 1 (CONFIG1). The oscillator
module can be configured for one of the following
modes of operation.
1. EC – CLKOUT function on RA4/CLKOUT pin,
CLKIN on RA5/CLKIN.
2. EC – I/O function on RA4/CLKOUT pin, CLKIN
on RA5/CLKIN.
3. INTOSC – CLKOUT function on RA4/CLKOUT
pin, I/O function on RA5/CLKIN
4. INTOSCIO – I/O function on RA4/CLKOUT pin,
I/O function on RA5/CLKIN
FIGURE 7-1:
SIMPLIFIED PIC^® MCU CLOCK SOURCE BLOCK DIAGRAM
FOSC<1:0>
(Configuration Word 1)
CLKIN
Internal Oscillator
500 kHz
MFINTOSC
0
32x
PLL
1
IRCF<1:0>
(OSCCON Register)
16 MHz/500 kHz
11
8 MHz/250 kHz
10
4 MHz/125 kHz
01
2 MHz/62.5 kHz
00
PLLEN
(Configuration Word 1)
EC
INTOSC
System Clock
(CPU and Peripherals)
 2010-2013 Microchip Technology Inc.
DS41430D-page 65