
9
INDUSTRIAL TEMPERATURE RANGE
IDT821034 QUAD PCM CODEC WITH PROGRAMMABLE GAIN
Figure
5.
Typical
Application
Circuit
Note:
1.
Recommended
value
for
R1
is
between
40
k
and
100
k
.
2.
The
value
of
R3
is
chosen
to
implement
the
desired
transmit
gain.
The
CODEC
Transmit
Gain
=
R1/R3.
3.
The
value
of
R2
is
chosen
to
cancel
the
echo
due
to
hybrid
and
impedance
mismatch.
Assume
the
receive
level
is
VFRO(t)
and
the
4-line
output
with
SLIC
input
properly
terminated
is
V4out(t),
the
value
of
R2
should
be
chosen
as
follows:
VFRO(t)/R2
=
V4out(t)/R3
VDD
CNF
DX
DR
TSX
FS
MCLK
BCLK
CO
CI
CS
CCLK
I
D
T
8
2
1
0
3
4
+5V
SUPPLY
VFRO
VDDA
GNDA
GND
I/O0_1
I/O0_0
VFXI
O0_2
O0_3
O0_4
CH0
SLIC
GSX0
K1
K2
K3K3
2k
VCC
0.1
F
0.1
F
68K
R1
R2
R3
off
/on
hook
line
reverse
Ring
Tip
TestBUS
RingBUS
protector
K1
K2
K3
V4out
V4in
Control Bus
PCM Bus
4
6
5
5
100
100
100
100