12.1.1.2 HS Modes

The High Speed (HS) oscillator modes support the use of quartz crystals or ceramic resonators connected to the OSC1 and OSC2 pins, as shown in the figures below. These modes work best for crystals or ceramic resonators that require operating frequencies from 4 MHz up to 32 MHz. Depending on the operating frequency, the appropriate HS power mode (8, 16, 24, or 32 MHz) should be selected to control the drive strength and optimize current consumption, which can help eliminate the need of an external series resistor.

The figures below show typical circuits for quartz crystal and ceramic resonators.

Figure 12-3. Quartz Crystal Operation
Note:
  1. A series resistor (RS) may be required for quartz crystals with low drive level.
  2. The value of RF varies with the Oscillator mode selected (typically between 2 MΩ and 10 MΩ).
Figure 12-4. Ceramic Resonator Operation
Note:
  1. A series resistor (RS) may be required for ceramic resonators with low drive level.
  2. The value of RF varies with the Oscillator mode selected (typically between 2 MΩ and 10 MΩ).
  3. An additional parallel feedback resistor (RP) may be required for proper ceramic resonator operation.