Section number Title Page
18.2.4 External Clock Source - CLKIN....................................................................................................................308
18.3 Pin Description..............................................................................................................................................................309
18.3.1 External Clock Reference..............................................................................................................................309
18.3.2 Oscillator IO (XTAL, EXTAL).....................................................................................................................309
18.3.3 CLKO - Output Pins......................................................................................................................................309
18.4 Memory Map and Register Descriptions......................................................................................................................310
18.4.1 PLL Control Register (OCCS_CTRL)...........................................................................................................310
18.4.2 PLL Divide-By Register (OCCS_DIVBY)....................................................................................................312
18.4.3 OCCS Status Register (OCCS_STAT)..........................................................................................................314
18.4.4 Oscillator Control Register 1 (OCCS_OSCTL1)...........................................................................................316
18.4.5 Oscillator Control Register 2 (OCCS_OSCTL2)...........................................................................................317
18.4.6 External Clock Check Reference (OCCS_CLKCHKR)................................................................................319
18.4.7 External Clock Check Target (OCCS_CLKCHKT)......................................................................................320
18.4.8 Protection Register (OCCS_PROT)...............................................................................................................320
18.5 Functional Description..................................................................................................................................................321
18.6 Relaxation Oscillators...................................................................................................................................................325
18.6.1 Trimming Frequency on the Internal 8 MHz Relaxation Oscillator..............................................................325
18.6.2 Trimming Frequency on the Internal 200 kHz Relaxation Oscillator...........................................................325
18.7 External Reference........................................................................................................................................................326
18.8 Crystal Oscillator..........................................................................................................................................................326
18.8.1 Switching Clock Sources...............................................................................................................................326
18.9 Phase Locked Loop.......................................................................................................................................................328
18.9.1 PLL Recommended Range of Operation.......................................................................................................328
18.9.2 PLL Lock Time Specification........................................................................................................................328
18.9.2.1 Lock Time Definition.................................................................................................................328
18.9.2.2 Parametric Influences on Reaction Time...................................................................................328
18.10 PLL Frequency Lock Detector Block...........................................................................................................................329
18.11 Loss of Reference Clock Detector................................................................................................................................329
18.12 Resets............................................................................................................................................................................330
MC56F823xx Reference Manual, Rev. 3, 10/2013
16 Freescale Semiconductor, Inc.