PIC12F1822 MICROCHIP [Microchip Technology], PIC12F1822 Datasheet - Page 55

• Manufacturer Part Number: PIC12F1822
• Description: 8/14-Pin Flash Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

5.0
5.1
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 perfor-
mance and minimizing power consumption. Figure 5-1
illustrates a block diagram of the oscillator module.
Clock sources can be supplied from external oscillators,
quartz crystal resonators, ceramic resonators and
Resistor-Capacitor (RC) circuits. In addition, the system
clock source can be supplied from one of two internal
oscillators and PLL circuits, with a choice of speeds
selectable via software. Additional clock features
include:
• Selectable system clock source between external
• Two-Speed Start-up mode, which minimizes
• Fail-Safe Clock Monitor (FSCM) designed to
• Oscillator Start-up Timer (OST) ensures stability
FIGURE 5-1:
 2010 Microchip Technology Inc.
or internal sources via software.
latency between external oscillator start-up and
code execution.
detect a failure of the external clock source (LP,
XT, HS, EC or RC modes) and switch
automatically to the internal oscillator.
of crystal oscillator sources
T1OSO
T1OSI
OSC2
OSC1
OSCILLATOR MODULE (WITH
FAIL-SAFE CLOCK MONITOR)
Overview
Oscillator
Oscillator
External
Oscillator
500 kHz
Internal
Source
Source
HFPLL
31 kHz
Block
SIMPLIFIED PIC
Timer1
T1OSCEN
Enable
Oscillator
Sleep
(HFINTOSC)
(MFINTOSC)
31 kHz (LFINTOSC)
16 MHz
500 kHz
®
MCU CLOCK SOURCE BLOCK DIAGRAM
PIC12F/LF1822/16F/LF1823
Preliminary
31.25 kHz
FOSC<2:0> = 100
62.5 kHz
125 kHz
500 kHz
250 kHz
16 MHz
8 MHz
4 MHz
2 MHz
1 MHz
31 kHz
IRCF<3:0>
The oscillator module can be configured in one of six
clock modes.
1.
2.
3.
4.
5.
6.
Clock Source modes are selected by the FOSC<2:0>
bits in the Configuration Word 1. The FOSC bits
determine the type of oscillator that will be used when
the device is first powered.
The EC clock mode relies on an external logic level
signal as the device clock source. The LP, XT, and HS
clock modes require an external crystal or resonator to
be connected to the device. Each mode is optimized for
a different frequency range. The RC clock mode
requires an external resistor and capacitor to set the
oscillator frequency.
The INTOSC internal oscillator block produces low,
medium, and high frequency clock sources, designated
LFINTOSC,
Internal Oscillator Block, Figure 5-1). A wide selection
of device clock frequencies may be derived from these
three clock sources.
EC – External clock (ECL, ECM, ECH. See
Section 5.2.1.1 “EC Mode”).
LP – 32 kHz Low-Power Crystal mode.
XT – Medium Gain Crystal or Ceramic Resonator
Oscillator mode.
HS – High Gain Crystal or Ceramic Resonator
mode.
RC – External Resistor-Capacitor (RC).
INTOSC – Internal oscillator.
4 x PLL
LP, XT, HS, RC, EC
Two-Speed Start-up and other modules
Internal Oscillator
WDT, PWRT, Fail-Safe Clock Monitor
MFINTOSC,
FOSC<2:0>
T1OSC
Clock Source Option
for other modules
Control
Clock
and
SCS<1:0>
Sleep
HFINTOSC.
DS41413A-page 55
Peripherals
CPU and
(see