8.2.1.2 LP, XT, HS Modes

The LP, XT and HS modes support the use of quartz crystal resonators or ceramic resonators connected to OSC1 and OSC2 (Figure 8-3). The three modes select a low, medium or high gain setting of the internal inverter-amplifier to support various resonator types and speed.

LP Oscillator mode selects the lowest gain setting of the internal inverter-amplifier. LP mode current consumption is the least of the three modes. This mode is designed to drive only 32.768 kHz tuning-fork type crystals (watch crystals). but can operate up to 100 kHz.

XT Oscillator mode selects the intermediate gain setting of the internal inverter-amplifier. XT mode current consumption is the medium of the three modes. This mode is best suited to drive crystals and resonators with a frequency range up to 4 MHz.

HS Oscillator mode selects the highest gain setting of the internal inverter-amplifier. HS mode current consumption is the highest of the three modes. This mode is best suited for resonators that require operating frequencies up to 20 MHz.

Figure 8-3 and Figure 8-4 show typical circuits for quartz crystal and ceramic resonators, respectively.

Note:

1. Quartz crystal characteristics vary according to type, package and manufacturer. The user may consult the manufacturer data sheets for specifications and recommended application.
2. Always verify oscillator performance over the V_DD and temperature range that is expected for the application.
3. For oscillator design assistance, reference the following Microchip application notes:
   • AN826, “Crystal Oscillator Basics and Crystal Selection for PIC^® and PIC^® Devices” (DS00826)
   • AN849, “Basic PIC^® Oscillator Design” (DS00849)
   • AN943, “Practical PIC^® Oscillator Analysis and Design” (DS00943)
   • AN949, “Making Your Oscillator Work” (DS00949)