NXP Semiconductors K22F series, Reference Manual, Page: 573 / 1407

• C1[IREFS] set to 1 to select the internal reference clock as the reference
clock source.
• C1[FRDIV] remain unchanged because the reference divider does not affect
the internal reference.
b. Loop until S[IREFST] is 1, indicating the internal reference clock has been
selected as the reference clock source.
c. Loop until S[CLKST] are 2'b01, indicating that the internal reference clock is
selected to feed MCGOUTCLK.
4. Lastly, FBI transitions into BLPI mode.
a. C2 = 0x02
• C2[LP] is 1
• C2[RANGE], C2[HGO], C2[EREFS], C1[IRCLKEN], and C1[IREFSTEN]
bits are ignored when the C1[IREFS] bit is set. They can remain set, or be
cleared at this point.
Chapter 25 Multipurpose Clock Generator (MCG)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 573