wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 49

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

w
Pre-Production
Once F
the recommendations in Table 16. The value of N.K can then be determined using the equation
above. FLL_REF_FREQ should be set as described in Table 16.
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. It is also recommended for best audio performance, that high input clocks
frequencies (above 1MHz), are used.
The register fields that control the FLL are described in Table 16. Example settings for a variety of
reference frequencies and output frequencies are shown in Table 17.
R3 (03h)
Power
Management 2
R60 (3Ch)
FLL Control 1
R61 (3Dh)
FLL Control 2
REGISTER
ADDRESS
VCO
has been determined, the value of FLL_FRATIO should be selected in accordance with
15
12
11:10
9
8
7:5
4:0
15:0
BIT
FLL_ENA
FLL_REF_FREQ
FLL_CLK_SRC
[1:0]
FLL_FRAC
FLL_OSC_ENA
FLL_CTRL_RAT
E
[2:0]
FLL_FRATIO
[4:0]
FLL_K[15:0]
LABEL
DEFAULT
0
1
0
0
0h
8
0h
FLL Digital enable
0 = FLL disabled
1 = FLL enabled
FLL_OSC_ENA must be enabled
before enabling FLL_ENA. The order is
important.
Low frequency reference locking
0 = Lock achieved after 509 ref clks
(Recommended for Reference clock >
48kHz)
1 = Lock achieved after 49 ref clks
(Recommended for Reference clock <=
48kHz)
FLL Clock source
00 = MCLK
01 = DAC LRCLK
10 = ADC LRCLK
11 = GPIO6
Fractional enable
0 = Integer Mode
1 = Fractional Mode
1 recommended in all cases
FLL Analogue enable
0 = FLL disabled
1 = FLL enabled
FLL_OSC_ENA must be enabled
before enabling FLL_ENA. The order is
important.
Frequency of the FLL control block
000 = F
001 = F
010 = F
011 = F
100 = F
101 = F
Recommended that these are not
changed from default.
CLK_VCO is divided by this integer,
valid from 1 .. 31.
1 recommended for high freq reference
8 recommended for low freq reference
Fractional multiply for CLK_REF
VCO
VCO
VCO
VCO
VCO
VCO
DESCRIPTION
/ 1 (Recommended value)
/ 2
/ 4
/ 8
/ 16
/ 32
PP, April 2009, Rev 3.0
WM8400
49