wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 47

• 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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OUTPUT SIGNAL PATH
There are two output signal paths from the analogue mixer. These are the Line Output (on the
LINEOUT pin) and the speaker output (on SPKOUTP and SPKOUTN).
The Line Output driver is enabled by setting LINEOUT_ENA. The Line Output can be muted or
adjusted using the LINEOUT_MUTE and LINEOUT_VOL register fields, as described in Table 27.
The Speaker Output signal path is enabled in two parts, using SPKPGA_ENA and SPK_ENA. When
powering up the speaker driver, the SPKPGA_ENA bit should be set before the SPK_ENA bit is set.
The reverse sequence should be followed when powering down the speaker driver. The Speaker
Output can be muted or adjusted using the SPKPGA_MUTE and SPKPGA_VOL register fields, as
described in Table 27.
The speaker driver incorporates pop suppression circuits controlled by the SPK_INV_MUTE and
OUT_SPK_CTRL registers. The default setting of these bits is logic 1. In normal operation, these bits
must be set to logic 0. In Class D mode, these bits are controlled automatically by the WM9081 when
SPK_ENA is written to. In Class AB mode, these bits must be set to logic 0 before SPK_ENA is
enabled.
To prevent "zipper noise", a zero-cross function is provided on the Line Output and Speaker Output
volume controls. When this feature is enabled, volume updates will not take place until a zero-
crossing is detected. In the case of a long period without zero-crossings, a timeout function is
provided. When the zero-cross function is enabled, the volume will update after the timeout period if
no earlier zero-cross has occurred. The timeout clock is enabled using CLK_TO_ENA, the timeout
period is set by CLK_TO_DIV. See “Clocking and Sample Rates” for more information on these
fields.
R2 (02h)
Analogue
Lineout
R3 (03h)
Analogue
Speaker PGA
REGISTER
ADDRESS
BIT
5:0
5:0
7
6
7
6
LINEOUT_MUTE
LINEOUT_ZC
LINEOUT_VOL
[5:0]
SPKPGA_MUTE
SPKPGA_ZC
SPKPGA_VOL
[5:0]
LABEL
DEFAULT
39h (0dB)
11_1001
1
0
1
0
LINEOUT Mute
0 = Un-mute
1 = Mute
LINEOUT Zero Cross Detection
0 = Change gain immediately
1 = Change gain on zero cross only
LINEOUT Volume
00 0000 = -57dB
00 0001 = -56dB
…
11 1001 = 0dB
…
11 1111 = 6dB
Speaker PGA Mute
0 = Un-mute
1 = Mute
Speaker PGA Zero Cross Detection
0 = Change gain immediately
1 = Change gain on zero cross only
Speaker PGA Volume
00 0000 = -57dB
00 0001 = -56dB
…
11 1001 = 0dB
…
11 1111 = 6dB
DESCRIPTION
PP, Rev 3.0, April 2009
WM9081
47