wm9714l Wolfson Microelectronics plc, wm9714l Datasheet - Page 50

• Manufacturer Part Number: wm9714l
• Description: Ac?97 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

WM9714L
MONOIN INPUT
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Pin 20 (MONOIN) is a mono input designed to connect to the receive path of a telephony device. The
pin connects directly to the record selector for phone call recording (Note: to record both sides of a
phone call, one ADC channel should record the MONOIN signal while the other channel records the
MIC signal). The record PGA adjusts the recording volume, and is controlled by register 12h or by
the ALC function (see “Record Gain” and “Automatic Level Control” sections).
Table 28 Record PGA Routing Control
To listen to the MONOIN signal, the signal passes through a separate PGA, controlled by register
08h. The signal can be routed into the headphone mixer (for normal phone call operation) and/or the
speaker mixer (for speakerphone operation), but not into the mono mixer (to prevent forming a
feedback loop). When the signal is not selected as an input to any of the mixers the output of the
PGA is muted automatically.
When not in use the MONOIN PGA can be powered down using the Powerdown register bit MOIN
(register 3Eh, bit 4).
MONOIN is biased internally to the reference voltage VREF. Whenever the input is muted or the
device placed into standby mode, the input remains biased to VREF using special anti-thump
circuitry to suppress any audible clicks when changing inputs.
Table 29 Mono PGA Control
14h
Record
Routing
08h
MONOIN
PGA Vol /
Routing
REGISTER
REGISTER
ADDRESS
ADDRESS
15:14
13:11
10:9
8
15
14
12:8
BIT
BIT
R2H
R2HVOL
R2M
R2MBST
M2H
M2S
MONOIN
VOL
LABEL
LABEL
11 (mute)
010 (0dB)
11 (mute)
0 (0dB)
1
1
01000
(0dB)
DEFAULT
DEFAULT
Record Mux to Headphone Mixer Path
Control
00 = stereo
01 = left record mux only
10 = right rec mux only
11=mute left and right
Record Mux to Headphone Mixer Path
Volume Control
000 = +6dB
… (+3dB steps)
111 = -15dB
Record Mux to Mono Mixer Path Control
00 = stereo
01 = left record mux only
10 = right record mux only
11 = mute left and right
Record Mux to Headphone Mixer Boost
Control
1 = +20dB
0 = 0dB
MONOIN to Headphone Mixer Mute
Control
1 = Mute
0 = No mute
MONOIN to Speaker Mixer Mute Control
1 = Mute
0 = No mute
MONOIN to Mixers Volume Control
00000 = +12dB
… (1.5dB steps)
11111 = -34.5dB
DESCRIPTION
DESCRIPTION
PP, Rev 3.2, October 2008
Pre-Production
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