WM8739 查看數據表（PDF） - Wolfson Microelectronics plc
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WM8739 Datasheet PDF : 35 Pages
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WM8739 / WM8739L
LINEIN
12.5K
VMID
Advanced Information
To
ADC
Figure 8 Line Input Schematic
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. Use of INBOTH reduces the required number of software
writes required. The line inputs 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[0:4]
7
LINMUTE
8
LRINBOTH
0000001
Right Line In
4:0 RINVOL[0:4]
7
RINMUTE
8
RLINBOTH
Table 2 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
1 = Enable Mute
0 = Disable Mute
Left to Right Channel Line Input Volume
and Mute Data Load Control
1 = Enable Simultaneous Load of
LINVOL[0:4] and LINMUTE to
RINVOL[0:4] and RINMUTE
0 = Disable Simultaneous Load
Right Channel Line Input Volume Control
11111 = +12dB
. . 1.5dB steps down to
00000 = -34.5dB
Left Channel Line Input Mute
1 = Enable Mute
0 = Disable Mute
Right to Left Channel Line Input Volume
and Mute Data Load Control
1 = Enable Simultaneous Load of
RINVOL[0:4] and RINMUTE to
LINVOL[0:4] and LINMUTE
0 = Disable Simultaneous Load
AI Rev 2.2 September 2001
12
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