Datasheet

PIC12(L)F1501
DS40001615C-page 42  2011-2015 Microchip Technology Inc.
5.0 OSCILLATOR MODULE
5.1 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 perfor-
mance and minimizing power consumption. Figure 5-1
illustrates a block diagram of the oscillator module.
Clock sources can be supplied from an external clock or
from one of two internal oscillators, with a choice of
speeds selectable via software. Additional clock features
include:
• Selectable system clock source between external
or internal sources via software.
• Fast start-up oscillator allows internal circuits to
power-up and stabilize before switching to the 16
MHz HFINTOSC
The oscillator module can be configured in one of the
following clock modes.
1. ECL – External Clock Low-Power mode
(0 MHz to 0.5 MHz)
2. ECM – External Clock Medium Power mode
(0.5 MHz to 4 MHz)
3. ECH – External Clock High-Power mode
(4 MHz to 20 MHz)
4. INTOSC – Internal oscillator (31 kHz to 16 MHz)
Clock Source modes are selected by the FOSC<1:0>
bits in the Configuration Words. The FOSC bits
determine the type of oscillator that will be used when
the device is first powered.
The ECH, ECM, and ECL clock modes rely on an
external logic level signal as the device clock source.
The INTOSC internal oscillator block produces a low and
high-frequency clock source, designated LFINTOSC and
HFINTOSC. (See Internal Oscillator Block, Figure 5-1). A
wide selection of device clock frequencies may be derived
from these two clock sources.