The Active Clock Tuning feature on the PIC16(L)F191xx family of devices can provide a higher accuracy clock source than the HFINTOSC alone. As shown in Section 2: Active Clock Tuning Accuracy, with the addition of an external crystal and associated capacitors for the Secondary Oscillator, this is achievable. In applications requiring a higher accuracy clock, instead of using an expensive external clock source, an inexpensive 32.768 kHz crystal tied to the SOSC pins and ACT can meet the clock specification of the application.