WM9714L_06 WOLFSON [Wolfson Microelectronics plc], WM9714L_06 Datasheet - Page 36

• Manufacturer Part Number: WM9714L_06
• Description: AC 97 Audio CODEC
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

WM9714L
AUDIO INPUTS
LINE INPUT
MICROPHONE INPUT
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The following sections give an overview of the analogue audio input pins and their function. For more
information on recommended external components, please refer to the “Applications Information”
section.
The LINEL and LINER inputs are designed to record line level signals, and/or to mix into one of the
analogue outputs.
Both pins are directly connected to the record selector. The record PGA adjusts the recording
volume, controlled by register 12h or by the ALC function.
For analogue mixing, the line input signals pass through a separate PGA, controlled by register 0Ah.
The signals can be mixed into the headphone, speaker and mono mixer paths (see “Audio Mixers”).
Each LINE-to-mixer path has an independent mute bit. When all LINE-to-mixer paths are muted the
line PGA is muted automatically. When the line inputs are not used, the line PGA can be switched off
to save power (see “Power Management” section).
LINEL and LINER are biased internally to the reference voltage VREF. Whenever the inputs are
muted or the device placed into standby mode, the inputs remain biased to VREF using special anti-
thump circuitry to suppress any audible clicks when changing inputs.
Table 22 Line Input Control
Additionally, line inputs can be used as single-ended microphone inputs through the record mux to
provide a clickless ALC function by bypassing offset introduced through the microphone pre-amps.
Note that the line inputs to the mixers should all be deselected if this is input configuration is used.
MICROPHONE PRE-AMPS
There are two microphone pre-amplifiers, MPA and MPB, which can be configured in a variety of
ways to accommodate up to 3 selectable differential microphone inputs or 2 differential microphone
inputs operating simultaneously for stereo or noise cancellation. The microphone input circuit is
shown in Figure 12.
0Ah
REGISTER
ADDRESS
15
14
13
12:8
4:0
BIT
L2H
L2S
L2M
LINEL
VOL
LINER
VOL
LABEL
1
1
1
01000
(0dB)
01000
(0dB)
DEFAULT
Mute LINE path to headphone mixer
1: Mute, 0: No mute (ON)
Mute LINE path to speaker mixer
1: Mute, 0: No mute (ON)
Mute LINE path to mono mixer
1: Mute, 0: No mute (ON)
LINEL input gain
00000: +12dB
… (1.5dB steps)
11111: -34.5dB
LINER input gain
similar to LINELVOL
DESCRIPTION
PP Rev 3.0 June 2006
Pre-Production
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