11 OSC - Oscillator Module
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.
- External clock oscillators
- Secondary Oscillator (SOSC)
- High-Frequency Internal Oscillator (HFINTOSC)
- Low-Frequency Internal Oscillator (LFINTOSC)
- Analog-to-Digital Converter RC Oscillator (ADCRC)
- Oscillator Start-up Timer (OST): Ensures stability of the Secondary Oscillator’s 32.768 kHz crystal oscillator.
- HFINTOSC Frequency Adjustment: Provides the ability to adjust the HFINTOSC frequency.
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).
RSTOSC | SFR Reset Values | Clock Source | |
COSC | OSCFRQ | ||
111 | 111 | 000 (1
MHz) | EXTOSC per FEXTOSC |
110 | 110 | HFINTOSC @ 1 MHz | |
101 | 101 | LFINTOSC | |
100 | 100 | SOSC | |
011 | 011 | Reserved | |
010 | 010 | Reserved | |
001 | 011 | Reserved | |
000 | 000 | 101 (32 MHz) | HFINTOSC @ 32 MHz |
- ECL: External Clock Low Power mode
- ECH: External Clock High Power mode
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.
The figure below illustrates a block diagram of the oscillator module.