PIC12F1840 MICROCHIP [Microchip Technology], PIC12F1840 Datasheet - Page 47

• Manufacturer Part Number: PIC12F1840
• Description: 8-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.
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
 2011 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.
OSCILLATOR MODULE (WITH
FAIL-SAFE CLOCK MONITOR)
Overview
Figure 5-1
Preliminary
The oscillator module can be configured in one of eight
clock modes.
1.
2.
3.
4.
5.
6.
7.
8.
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,
of device clock frequencies may be derived from these
three clock sources.
ECL – External Clock Low Power mode
(0 MHz to 0.5 MHz)
ECM – External Clock Medium Power mode
(0.5 MHz to 4 MHz)
ECH – External Clock High Power mode
(4 MHz to 32 MHz)
LP – 32 kHz Low-Power Crystal mode.
XT – Medium Gain Crystal or Ceramic Resonator
Oscillator mode (up to 4 MHz)
HS – High Gain Crystal or Ceramic Resonator
mode (4 MHz to 20 MHz)
RC – External Resistor-Capacitor (RC).
INTOSC – Internal oscillator (31 kHz to 32 MHz).
MFINTOSC,
PIC12F/LF1840
Figure
and
5-1). A wide selection
HFINTOSC.
DS41441A-page 47
(see