Rev 1.9.1 Feb.09
Proprietary and Confidential
55
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Note: Data mixing is not supported. If mixing of voice signal is
required, it must be done by the host processor.
Figure 4-3: MC8775V / MC8785V / MC8790V / MC8791V / MC8792V Audio system block
Modes of operation
These
modules
support
four
operational
modes:
headset,
handset,
car
kit,
and
speakerphone—end
products
can
use
any
combination
of
these
modes.
The
host
device
must
use
host
‐
modem
messaging
to
tell
the
module
which
mode
to
use
for
each
call.
Sidetone support
The
sidetone
path
mixes
the
near
‐
end
transmit
voice
to
the
near
‐
end
receive.
This
gives
the
near
‐
end
user
some
feedback
that
indicates
that
the
call
is
up
and
that
the
audio
system
is
functioning.
The
sidetone
path
can
be
enabled
in
either
the
PDA
codec
or
the
Mini
Card
modem—each
path
is
equally
valid.
It
should
not
be
added
to
both
devices,
and
for
speakerphone
or
car
kit
applications,
both
sidetone
paths
should
be
disabled.
The
typical
handset
sidetone
is
12
dB
below
transmit
voice
levels.
Decoder
RX DAC
Encoder
TX ADC
HPF &
Slope
HPF
Echo Cancel
la
ti
on
NS &
AAGC
Tx FIR
Rx FIR
13K CELP/
EVRC
Decoder
AAGC
13 bit A/D
13 bit D/A
CodecRxGain
RX_HPF_DIS_N
CodecSTGain
CodecTxGain
TX_HPF_DIS_N
TX_SLOPE_FILT_DIS_N
MIC_AMP1_GAIN
-6dB to +49.5dB
in 1.5dB steps
nsSwitch
TxPCMFilt TxVolume
RxVolume
RxPCMFilt
AMP_SEL
001 010 100
35mW @ +3dBm0
RF Filter
33n
22p
PC
M I/
F
+12dB
-25dB
-84dB
+12dB
-3dB
-84dB
+12dB
0dB
-81dB
+12dB
-48dB
-96dB
+12dB
0dB
-84dB
57.3mVrms
@ 0dBm0
SPK_P
SPK_N
MIC_P
MIC_N
13K CELP/
EVRC
Encoder
DTMF
Encoder
DTMF Rx Gain
DTMF Tx Gain
DTMF
Decoder
Audio In
Audio Out
RF
Interface
PCM Audio interface