2.1.2 Multiple Oscillator Options and Features

All of the devices in the PIC18F27/47Q10family offer several different oscillator options. The PIC18F27/47Q10 family can be clocked from several different sources:

• HFINTOSC
  • 1-64 MHz precision digitally controlled internal oscillator
• LFINTOSC
  • 31 kHz internal oscillator
• EXTOSC
  • External clock (EC)
  • Low-power oscillator (LP)
  • Medium power oscillator (XT)
  • High power oscillator (HS)
• SOSC
  • Secondary oscillator circuit optimized for 31 kHz clock crystals
• A Phase Lock Loop (PLL) frequency multiplier (4x) is available to the External Oscillator modes enabling clock speeds of up to 64 MHz
• Fail-Safe Clock Monitor: This option constantly monitors the main clock source against a reference signal provided by the LFINTOSC. If a clock failure occurs, the controller is switched to the internal oscillator block, allowing for continued operation or a safe application shutdown.