
PLL Programming
MOTOROLA
Phase-Locked Loop and Clock Dividers
4-3
PLLDIV
(See Note 5)
Input frequency (Fin) is divided by (PLLDIV + 2) to determine the PLL compare frequency.
Note:
1. If this bit is written 0, the PLL is not used, and the crystal clock is sent directly to the CPU. Write this bit 0 before
changing any other bit in this register. Write back to 1 after writing new settings. After writing 1 to this bit, new
setting will become active after a hardware controlled delay. This delay is ca. 0.5 mS. Clock frequencies described
in other notes are only valid when this bit is set 1.
Note:
2. PLL may require up to 10.0 mS to lock
Note:
3. Fin is input frequency to PLL. Nominal setting for CRSEL is ‘1’ for 33.8688 Mhz X-tal, ‘0’ for 16.9344 Mhz X-tal.
Note:
4. AUDIOCLK is clock for audio interfaces. May be 11.2896MHz, 16.9344 or 33.8688 Mhz.
Note:
5. Fvco = Fin * (VCODIV + 2)/ (PLLDIV + 2)
Note:
6. FVCOOUT depends on Fvco (note 5) and VCOOUT setting as shown in the following table:
Note:
7. This bit selects between two different functions implemented on an external pin.
Note:
8. Fcpu = FVCOOUT / CPUDIV; Fcpu is the frequency the processor is running at.
Note:
9. If field is “000”, divide by 8
Note:
10. Fvco max. is 400 Mhz
Note:
11. This bit selects the function of the aux_dsi/intmon1, aux_bkpt_b/TA, aux_dsclk/intmon2, and aux-dso/A27 pins.
If this bit = 0, the primary function (aux_dsi,aux_bkpt_b,aux_dsclk, and aux_dso) is selected. If this bit = 1, the
secondary function (intmon1, TA,intmon2, and A27) is selected.
Note:
12. This field determines the frequency of the DAC clocks. Fxtal/3 and Fxtal/4 should not be used normally:
Table 4-2 PLLCR Bit Descriptions (Continued)
BIT NAME
DESCRIPTION
VCO OUT
SETTING
FVCO OUT
0
Fvco
1
Fvco/2
2
Fvco/2
3
Fvco/4
CRSEL
CLSEL
FREQUENCY
MCLK2
FREQUENCY
MCLK1
1
000
FXTAL
FXTAL/2
1
001
FXTAL
1
010
FXTAL/2
1
011
FXTAL/2
FXTAL
1
100
FXTAL
FXTAL/2
1
101
FXTAL
1
110
FXTAL/2
1
111
FXTAL/2
FXTAL
0
000
FXTAL/2
0
001
FXTAL/2
FXTAL/3
0
010
FXTAL/2
FXTAL/4
0
011
FXTAL/3
FXTAL/2
0
100
FXTAL/3
0
101
FXTAL/3
FXTAL/4
0
110
FXTAL/4
FXTAL/2
0
111
FXTAL/4
FXTAL/3
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Freescale Semiconductor, Inc.
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