Oscillator Module Overview

The oscillator module contains multiple clock sources and selection features that allow it to be used in a wide range of applications while maximizing performance and minimizing power consumption.

Clock sources can be supplied either internally or externally. External sources include:
Internal sources include:
Special features of the oscillator module include:

The Reset Oscillator (RSTOSC) Configuration bits determine the type of oscillator that will be used when the device runs after a Reset, including when the device is first powered up (see the table below).

Table 1. RSTOSC Selection Table
RSTOSC SFR Reset Values Clock Source
COSC OSCFRQ
11 11 000 EXTOSC per FEXTOSC
10 10 HFINTOSC @ 1 MHz
01 01 LFINTOSC
00 00 101 HFINTOSC @ 32 MHz
If an external clock source is selected by the RSTOSC bits, the External Oscillator Mode Select (FEXTOSC) Configuration bits must be used to select the external clock mode. These modes include:

The ECH and ECL modes rely on an external logic-level signal as the device clock source. Each mode is optimized for a specific frequency range. The internal oscillator block produces both low-frequency and high-frequency clock signals, designated LFINTOSC and HFINTOSC, respectively. Multiple system operating frequencies may be derived from these clock sources.

Figure 1 illustrates a block diagram of the oscillator module.

Figure 1. Clock Source Block Diagram