NXP Semiconductors K22F series, Reference Manual, Page: 539 / 1407

Chapter 25
Multipurpose Clock Generator (MCG)
25.1 Introduction
NOTE
For the chip-specific implementation details of this module's
instances, see the chip configuration information.
The multipurpose clock generator (MCG) module provides several clock source choices
for the MCU.
The module contains a frequency-locked loop (FLL) and a phase-locked loop (PLL). The
FLL is controllable by either an internal or an external reference clock. The PLL is
controllable by the external reference clock. The module can select either an FLL or PLL
output clock, or a reference clock (internal or external) as a source for the MCU system
clock. The MCG operates in conjuction with a crystal oscillator, which allows an external
crystal, ceramic resonator, or another external clock source to produce the external
reference clock.
25.1.1 Features
Key features of the MCG module are:
• Frequency-locked loop (FLL):
• Digitally-controlled oscillator (DCO)
• DCO frequency range is programmable for up to four different frequency ranges.
• Option to program and maximize DCO output frequency for a low frequency
external reference clock source.
• Option to prevent FLL from resetting its current locked frequency when
switching clock modes if FLL reference frequency is not changed.
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 539