wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 69

• Manufacturer Part Number: wm9081
• Description: Mono Dac With 2.6w Class Ab/d Speaker Driver, Dynamic Range Controller And Retune Mobile Parametric Equalizer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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The FLL operating frequency, F
F
F
Note that the output frequencies that do not lie within the ranges quoted above cannot be guaranteed
across the full range of device operating temperatures.
In order to follow the above requirements for F
according to the desired output F
Table 40 Selection of FLL_OUTDIV
The value of FLL_FRATIO should be selected as described in Table 41.
Table 41 Selection of FLL_FRATIO
In order to determine the remaining FLL parameters, the FLL operating frequency, F
calculated, as given by the following equation:
The value of FLL_N and FLL_K can then be determined as follows:
Note that F
For best performance, FLL Fractional Mode should always be used. Therefore, if the calculations
yield an integer value of N.K, then it is recommended to adjust FLL_FRATIO in order to obtain a non-
integer value of N.K.
REF
VCO
2.8125 MHz - 3.125 MHz
5.625 MHz - 6.25 MHz
11.25 MHz - 12.5 MHz
22.5 MHz - 25 MHz
1MHz - 13.5MHz
256kHz - 1MHz
128kHz - 256kHz
64kHz - 128kHz
Less than 64kHz
REFERENCE FREQUENCY F
is the input frequency, as determined by FLL_CLK_REF_DIV.
must be in the range 90-100 MHz. Frequencies outside this range cannot be supported.
OUTPUT FREQUENCY F
F
F
F
N.K = F
REF
OUT
VCO
VCO
is the input frequency, after division by FLL_CLK_REF_DIV, where applicable.
= (F
= (F
= (F
VCO
VCO
OUT
REF
/ (FLL_FRATIO x F
/ FLL_OUTDIV)
x FLL_OUTDIV)
x N.K x FLL_FRATIO)
VCO
OUT
OUT
is set according to the following equation:
REF
, as described in Table 40.
REF
4h (divide by 32)
3h (divide by 16)
2h (divide by 8)
1h (divide by 4)
0h (divide by 1)
1h (divide by 2)
2h (divide by 4)
3h (divide by 8)
4h (divide by 16)
)
VCO
, the value of FLL_OUTDIV should be selected
FLL_OUTDIV
FLL_FRATIO
PP, Rev 3.0, April 2009
VCO
WM9081
, must be
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