WM8956 View Datasheet(PDF) - Cirrus Logic
Part Name
Description
MFG CO.
'WM8956' PDF : 80 Pages View PDF
WM8956
REGISTER BIT
LABEL
ADDRESS
7
RMP3
8
RMN1
Table 3 Input PGA Control
DEFAULT
Production Data
DESCRIPTION
0
Connect RINPUT3 to non-inverting input of
Right Input PGA
0 = RINPUT3 not connected to PGA
1 = RINPUT3 connected to PGA
(Constant input impedance)
1
Connect RINPUT1 to inverting input of
Right Input PGA
0 = RINPUT1 not connected to PGA
1 = RINPUT1 connected to PGA
INPUT PGA VOLUME CONTROLS
The input PGAs have a gain range from -17.25dB to +30dB in 0.75dB steps. The gains from the
inverting inputs (LINPUT1 and RINPUT1) to the PGA outputs and from the non-inverting inputs
(LINPUT2/RINPUT2 and LINPUT3/RINPUT3) to the PGA output are always common in differential
configuration and controlled by the register bits LINVOL[5:0] and RINVOL[5:0].
The left and right input PGAs can be independently muted using the LINMUTE and RINMUTE register
bits.
To allow simultaneous volume updates of left and right channels, PGA gains are not altered until a 1
is written to the IPVU bit.
To prevent "zipper noise", 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 TOEN register bit),
the volume will update automatically after a timeout. The timeout period is set by TOCLKSEL. Note
that an MCLK must be input to the device and SYSCLK running internally to use the timeout function.
REGISTER
ADDRESS
R0 (00h)
Left Channel
PGA
BIT
8
LABEL
IPVU
7
LINMUTE
6
LIZC
5:0
LINVOL
[5:0]
R1 (01h)
8
Right Channel
PGA
IPVU
DEFAULT
DESCRIPTION
0
1
0
010111
( 0dB )
0
Input PGA Volume Update
0 = Store LINVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (left = LINVOL, right =
intermediate latch)
Left Input PGA Analogue Mute
1 = Enable Mute
0 = Disable Mute
Note: IPVU must be set to un-mute.
Left Input PGA Zero Cross Detector
1 = Change gain on zero cross only
0 = Change gain immediately
Left Input PGA Volume Control
111111 = +30dB
111110 = +29.25dB
. . 0.75dB steps down to
000000 = -17.25dB
Input PGA Volume Update
0 = Store RINVOL in intermediate
latch (no gain change)
1 = Update left and right channel
gains (right = RINVOL, left =
intermediate latch)
w
PD, November 2011, Rev 4.1
20
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