WM8959 Wolfson Microelectronics Ltd., WM8959 Datasheet - Page 63

• Manufacturer Part Number: WM8959
• Description: Mobile Multimedia DAC with Dual-mode Class AB/D Speaker Driver
• Manufacturer: Wolfson Microelectronics Ltd.

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Pre-Production
The speaker mixer SPKMIX, the speaker PGA SPKPGA and the outputs SPKN and SPKP are
controlled as described in Table 29. Care should be taken to avoid clipping when enabling more than
one path to the speaker mixer.
Register bits SPKATTN control the speaker output attenuation and can be used to avoid clipping
when more than one full scale signal is input to the mixer. Fine adjustment of the speaker output can
be made using the SPKVOL register field.
To prevent "zipper noise" when adjusting the SPKVOL, a zero-cross function is provided so that,
when enabled, volume updates will not take place until a zero-crossing is detected. In the event of a
long period without zero-crossings, a timeout function is available. When this function is enabled
(using the TOCLK_ENA register bit), the volume will update after the timeout period if no earlier zero-
cross has occurred. The timeout period is set by TOCLK_RATE. See “Clocking and Sample Rates”
for more information on these fields.
Table 29 Speaker Output Volume Control
R54 (36h)
R34 (22h)
R38 (26h)
REGISTER
ADDRESS
BIT
1:0
6:0
7
6
5
4
3
2
1
0
7
LB2SPK
RB2SPK
LI2SPK
RI2SPK
LOPGASPK
ROPGASPK
LDSPK
RDSPK
SPKATTN
[1:0]
SPKZC
SPKVOL
[6:0]
LABEL
DEFAULT
0b
0b
0b
0b
0b
0b
0b
0b
11b
0b
79h
(0dB)
AINLMUX Output to SPKMIX
0 = Mute
1 = Un-mute
AINRMUX Output to SPKMIX
0 = Mute
1 = Un-mute
LIN2 to SPKMIX
0 = Mute
1 = Un-mute
RIN2 to SPKMIX
0 = Mute
1 = Un-mute
LOPGA to SPKMIX
0 = Mute
1 = Un-mute
ROPGA to SPKMIX
0 = Mute
1 = Un-mute
Left DAC to SPKMIX
0 = Mute
1 = Un-mute
Note: LDSPK must be muted when
LDLO=1
0 = Mute
1 = Un-mute
Note: RDSPK must be muted when
RDRO=1
Speaker Output Attenuation (SPKN
and SPKP)
00 = 0dB
01 = -6dB
10 = -12dB
11 = mute
SPKPGA Zero Cross Enable
0 = Zero cross disabled
1 = Zero cross enabled
SPKPGA Volume
(see Table 28 for SPKPGA volume
control range)
Right DAC to SPKMIX
DESCRIPTION
PP, May 2008, Rev 3.1
WM8959
63