WM8734 Просмотр технического описания (PDF) - Wolfson Microelectronics plc
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WM8734 Datasheet PDF : 46 Pages
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WM8734
LINEIN
12.5K
VMID
Production Data
To
ADC
Figure 8 Line Input Schematic
The gain between the line inputs and the ADC is logarithmically adjustable from +12dB to –34.5dB in
1.5dB steps under software control. The ADC Full Scale input is 1.0V rms at AVDD = 3.3 volts. Any
voltage greater than full scale will possibly overload the ADC and cause distortion. Note that the full
scale input tracks directly with AVDD. The gain is independently adjustable on both Right and Left
Line Inputs. However, by setting the INBOTH bit whilst programming the volume control, both
channels are simultaneously updated with the same value. Use of INBOTH reduces the required
number of software writes required. The line inputs to the ADC can be muted in the analogue domain
under software control. The software control registers are shown below.
REGISTER
ADDRESS
0000000
Left Line In
BIT
LABEL
4:0 LINVOL[4:0]
7
LINMUTE
8
LRINBOTH
0000001
Right Line In
4:0 RINVOL[4:0]
7
RINMUTE
8
RLINBOTH
Table 1 Line Input Software Control
DEFAULT
DESCRIPTION
10111
( 0dB )
1
0
10111
( 0dB )
1
0
Left Channel Line Input Volume
Control
11111 = +12dB . . 1.5dB steps down
to 00000 = -34.5dB
Left Channel Line Input Mute to ADC
1 = Enable Mute
0 = Disable Mute
Left to Right Channel Line Input
Volume and Mute Data Load Control
1 = Enable Simultaneous Load of
LINVOL[4:0] and LINMUTE to
RINVOL[4:0] and RINMUTE
0 = Disable Simultaneous Load
Right Channel Line Input Volume
Control
11111 = +12dB . .1.5dB steps down
to 00000 = -34.5dB
Right Channel Line Input Mute to
ADC
1 = Enable Mute
0 = Disable Mute
Right to Left Channel Line Input
Volume and Mute Data Load Control
1 = Enable Simultaneous Load of
RINVOL[4:0] and RINMUTE to
LINVOL[4:0] and LINMUTE
0 = Disable Simultaneous Load
w
PD Rev 4.1 November 2006
17
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