The Main PLL uses the reference clock from pins X1 (external oscillator) or X1/X2 (external crystal/resonator). The input clock is multiplied by an integer multiplier and a fractional multiplier as selected by the SPLLIMULT and SPLLFMULT fields of the SYSPLLMULT register. For example, to achieve PLL multiply of 28.5, the integer multiplier should be set to 28, and the fractional multiplier to 0.5. The output clock from the Main PLL must be between 150 MHz and 300 MHz. The PLL output clock is then divided by 2 before entering a mux that selects between this clock and the PLL input clock – OSCCLK (used in PLL bypass mode). The PLL bypass mode is selected by setting the SPLLIMULT field of the SYSPLLMULT register to 0. The output clock from the mux next enters a divider controlled by the SYSDIVSEL register, after which the output clock becomes the PLLSYSCLK. Figure 8-8 shows the Main PLL function and configuration examples. Table 8-19 to Table 8-22 list the integer multiplier configuration values.
Table 8-19 Main PLL Integer Multiplier Configuration
(Bypass PLL to × 31)SPLLIMULT(6:0) | MULT VALUE |
---|
0000000 b | Bypass PLL |
0000001 b | × 1 |
0000010 b | × 2 |
0000011 b | × 3 |
0000100 b | × 4 |
0000101 b | × 5 |
0000110 b | × 6 |
0000111 b | × 7 |
| |
0001000 b | × 8 |
0001001 b | × 9 |
0001010 b | × 10 |
0001011 b | × 11 |
0001100 b | × 12 |
0001101 b | × 13 |
0001110 b | × 14 |
0001111 b | × 15 |
| |
0010000 b | × 16 |
0010001 b | × 17 |
0010010 b | × 18 |
0010011 b | × 19 |
0010100 b | × 20 |
0010101 b | × 21 |
0010110 b | × 22 |
0010111 b | × 23 |
| |
0011000 b | × 24 |
0011001 b | × 25 |
0011010 b | × 26 |
0011011 b | × 27 |
0011100 b | × 28 |
0011101 b | × 29 |
0011110 b | × 30 |
0011111 b | × 31 |
Table 8-20 Main PLL Integer Multiplier Configuration
(× 32 to × 63)SPLLIMULT(6:0) | MULT VALUE |
---|
0100000 b | × 32 |
0100001 b | × 33 |
0100010 b | × 34 |
0100011 b | × 35 |
0100100 b | × 36 |
0100101 b | × 37 |
0100110 b | × 38 |
0100111 b | × 39 |
| |
0101000 b | × 40 |
0101001 b | × 41 |
0101010 b | × 42 |
0101011 b | × 43 |
0101100 b | × 44 |
0101101 b | × 45 |
0101110 b | × 46 |
0101111 b | × 47 |
| |
0110000 b | × 48 |
0110001 b | × 49 |
0110010 b | × 50 |
0110011 b | × 51 |
0110100 b | × 52 |
0110101 b | × 53 |
0110110 b | × 54 |
0110111 b | × 55 |
| |
0111000 b | × 56 |
0111001 b | × 57 |
0111010 b | × 58 |
0111011 b | × 59 |
0111100 b | × 60 |
0111101 b | × 61 |
0111110 b | × 62 |
0111111 b | × 63 |
Table 8-21 Main PLL Integer Multiplier Configuration
(× 64 to × 95)SPLLIMULT(6:0) | MULT VALUE |
---|
1000000 b | × 64 |
1000001 b | × 65 |
1000010 b | × 66 |
1000011 b | × 67 |
1000100 b | × 68 |
1000101 b | × 69 |
1000110 b | × 70 |
1000111 b | × 71 |
| |
1001000 b | × 72 |
1001001 b | × 73 |
1001010 b | × 74 |
1001011 b | × 75 |
1001100 b | × 76 |
1001101 b | × 77 |
1001110 b | × 78 |
1001111 b | × 79 |
| |
1010000 b | × 80 |
1010001 b | × 81 |
1010010 b | × 82 |
1010011 b | × 83 |
1010100 b | × 84 |
1010101 b | × 85 |
1010110 b | × 86 |
1010111 b | × 87 |
| |
1011000 b | × 88 |
1011001 b | × 89 |
1011010 b | × 90 |
1011011 b | × 91 |
1011100 b | × 92 |
1011101 b | × 93 |
1011110 b | × 94 |
1011111 b | × 95 |
Table 8-22 Main PLL Integer Multiplier Configuration
(× 96 to × 127)SPLLIMULT(6:0) | MULT VALUE |
---|
1100000 b | × 96 |
1100001 b | × 97 |
1100010 b | × 98 |
1100011 b | × 99 |
1100100 b | × 100 |
1100101 b | × 101 |
1100110 b | × 102 |
1100111 b | × 103 |
| |
1101000 b | × 104 |
1101001 b | × 105 |
1101010 b | × 106 |
1101011 b | × 107 |
1101100 b | × 108 |
1101101 b | × 109 |
1101110 b | × 110 |
1101111 b | × 111 |
| |
1110000 b | × 112 |
1110001 b | × 113 |
1110010 b | × 114 |
1110011 b | × 115 |
1110100 b | × 116 |
1110101 b | × 117 |
1110110 b | × 118 |
1110111 b | × 119 |
| |
1111000 b | × 120 |
1111001 b | × 121 |
1111010 b | × 122 |
1111011 b | × 123 |
1111100 b | × 124 |
1111101 b | × 125 |
1111110 b | × 126 |
1111111 b | × 127 |