wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 58

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

WM8351
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12.4.1
To generate 12.288 MHz output (F
Note that, for best performance, FLL Fractional Mode should always be used. If the calculations yield
an integer value of N.K, then it is recommended to adjust FLL_RATIO in order to obtain a non-integer
value of N.K.
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EXAMPLE FLL CALCULATION
Determine FLL_OUTDIV for the required output frequency as given by Table 16:
For F
Calculate F
F
Calculate the required N.K x FLL_RATIO for the given F
N.K x FLL_RATIO = F
Determine FLL_REF_FREQ for the given F
For F
Determine FLL_RATIO as given by Table 17:
For High Frequency Reference, FLL_RATIO = 1
Calculate N.K for the given FLL_RATIO:
N.K = 8.192 / 1 = 8.192
Determine FLL_N and FLL_K from the integer and fractional portions of N.K:
FLL_N is 8. FLL_K is 0.192
Set FLL_FRAC according to whether fractional mode is required:
FLL_K is 0.192, so fractional mode is required; FLL_FRAC = 1
VCO
OUT
= F
REF
OUT
= 12MHz, FLL_REF_FREQ = 0
= 12.288 MHz, FLL_OUTDIV = 2h (divide by 8)
VCO
* FLL_OUTDIV = 12.288 MHz * 8 = 98.304 MHz
for the given FLL_OUTDIV:
VCO
OUT
/ F
) from a 12.000 MHz reference clock (F
REF
= 8.192
REF
as given by Table 17:
REF
and F
VCO
PD, June 2009, Rev 4.1
REF
.:
):
Production Data
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