wm8952 Wolfson Microelectronics plc, wm8952 Datasheet - Page 17

• Manufacturer Part Number: wm8952
• Description: Mono Adc With Microphone Pre-amplifier
• Manufacturer: Wolfson Microelectronics plc

Pre Production
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Table 4 Input PGA Volume Control
AUXILIARY INPUT
Figure 7 Auxiliary Input Circuit
Table 5 Auxiliary Input Buffer Control
An auxiliary input circuit (Figure 7) is provided which consists of an amplifier which can be configured
either as an inverting buffer for a single input signal or as a mixer/summer for multiple inputs with the
use of external resistors. The circuit is enabled by the register bit AUXEN.
The AUXMODE register bit controls the auxiliary input mode of operation:
In buffer mode (AUXMODE=0) the switch labelled AUXSW in Figure 7 is open and the signal at the
AUX pin will be buffered and inverted through the aux circuit using only the internal components.
In mixer mode (AUXMODE=1) the on-chip input resistor is bypassed, this allows the user to sum in
multiple inputs with the use of external resistors.
variations through this path from part to part due to the variation of the internal 20kΩ resistors
relative to the higher tolerance external resistors.
R45
Input PGA
volume
control
R32
ALC control 1
R1
Power
management 1
R44
Input control
REGISTER
ADDRESS
REGISTER
ADDRESS
7
6
5:0
8
BIT
6
3
BIT
INPPGAZC
INPPGAMUTE
INPPGAVOL
ALCSEL
AUXEN
AUXMODE
LABEL
LABEL
0
1
010000
0
0
0
DEFAULT
DEFAULT
When used in this mode there will be gain
Input PGA zero cross enable:
0=Update gain when gain register changes
1=Update gain on 1
register write.
Mute control for input PGA:
0=Input PGA not muted, normal operation
1=Input PGA muted (and disconnected from
the following input BOOST stage).
Input PGA volume
000000 = -12dB
000001 = -11.25db
.
010000 = 0dB
.
111111 = 35.25dB
ALC function select:
0=ALC off (PGA gain set by INPPGAVOL
register bits)
1=ALC on (ALC controls PGA gain)
Auxiliary input buffer enable
0 = OFF
1 = ON
0 = inverting buffer
1 = mixer (on-chip input resistor bypassed)
DESCRIPTION
DESCRIPTION
PP, Rev 3.0, December 2008
st
zero cross after gain
WM8952
17