wm9712l Wolfson Microelectronics plc, wm9712l Datasheet - Page 15

• Manufacturer Part Number: wm9712l
• Description: Ac?97 Audio And Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
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AUDIO INPUTS
LINE INPUT
MICROPHONE INPUT
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 LINEINL and LINEINR 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 1Ch or by the ALC function.
For analogue mixing, the line input signals pass through a separate PGA, controlled by register 10h.
The signals can be routed into all three output mixers (headphone, speaker and phone). Each
LINEIN-to-mixer path has an independent mute bit. When the line inputs are not used, the line-in
PGA can be switched off to save power (see “Power Management” section).
LINEINL and LINEINR 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 2 Line Input Control
The MIC1 and MIC2 inputs are designed for direct connection to single-ended mono, stereo or
differential mono microphone. If the microphone is mono, the same signal appears on both left and
right channels. In stereo mode, MIC1 is routed to the left and MIC2 to the right channel.
For voice recording, the microphone signal is directly connected to the record selector. The record
PGA adjusts the recording volume, controlled by register 1Ch or by the ALC function.
For analogue mixing, the signal passes through a separate PGA, controlled by register 0Eh. The
microphone signal can be routed into the phone mixer (for normal phone call operation) and/or the
headphone mixer (using register 14h, see “Audio Mixers / Sidetone Control” section), but not into the
speaker mixer (to prevent acoustic feedback from the speaker into the microphone). When the
microphone inputs are not used, the microphone PGA can be switched off to save power (see
“Power Management” section).
MIC1 and MIC2 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.
10h
REGISTER
ADDRESS
12:8
4:0
15
14
13
BIT
LINEINL
VOL
LINEINR
VOL
L2H
L2S
L2P
LABEL
01000
(0dB)
01000
(0dB)
1
1
1
DEFAULT
LINEINL input gain
00000: +12dB
… (1.5dB steps)
11111: -34.5dB
LINEINR input gain
similar to LINEINLVOL
Mute LINEIN path to headphone mixer
1: Mute, 0: No mute (ON)
Mute LINEIN path to speaker mixer
1: Mute, 0: No mute (ON)
Mute LINEIN path to phone mixer
1: Mute, 0: No mute (ON)
DESCRIPTION
PD Rev 4.5 August 2006
WM9712L
15