wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 50

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
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Table 16 FLL Register Map
FLL POWER DOMAIN
Operation of the FLL requires an appropriate power supply to be connected to the FLLVDD power
domain. This supply is referenced to AGND. The operating range for this supply is detailed in the
“Recommended Operating Conditions” section.
EXAMPLE FLL CALCULATION
To generate 12.288 MHz output (F
R62 (3Eh)
FLL Control 3
R63 (3Fh)
FLL Control 4
REGISTER
ADDRESS
•
•
•
•
•
•
•
•
Determine FLL_OUTDIV for the required output frequency as given by Table 15:-
For F
Calculate F
F
Calculate the required N.K x FLL_FRATIO for the given F
N.K x FLL_FRATIO = F
Determine FLL_REF_FREQ for the given F
For F
Determine FLL_FRATIO as given by Table 16:-
For High Frequency Reference, FLL_FRATIO = 1
Calculate N.K for the given FLL_FRATIO:-
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
9:0
6:3
2:0
* FLL_OUTDIV = 12.288 MHz * 8 = 98.304 MHz
BIT
for the given FLL_OUTDIV:-
FLL_N[9:0]
FLL_TRK_GAIN
[3:0]
FLL_OUTDIV
[2:0]
VCO
OUT
LABEL
/ F
) from a 12.000 MHz reference clock (F
REF
= 8.192
DEFAULT
0h
0h
3h
REF
as given by Table 16:-
Integer multiply for CLK_REF
Gain applied to error
0000 = x 1 (Recommended value)
0001 = x 2
0010 = x 4
0011 = x 8
0100 = x 16
0101 = x 32
0110 = x 64
0111 = x 128
1000 = x 256
Recommended that these are not
changed from default.
F
000 = F
001 = F
010 = F
011 = F
100 = F
101 = Reserved
110 = Reserved
111 = Reserved
OUT
REF
clock divider
and F
VCO
VCO
VCO
VCO
VCO
/ 2
/ 4
/ 8 (best performance)
/ 16
/ 32
DESCRIPTION
VCO
REF
PP, April 2009, Rev 3.0
):
.:-
Pre-Production
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