The Specified-Frequency Internal Oscillator (SFINTOSC) generates a constant 1MHz clock output. The SFINTOSC clock signal is created from the HFINTOSC using dynamic divider logic, which provides constant SFINTOSC clock rates regardless of the selected HFINTOSC frequency.

The SFINTOSC cannot be used as the system clock, but provides a constant 1 MHz clock signal that is used for NVM Write and Erase operations. Additionally, SFINTOSC can be used as a clock source for certain peripherals.