LUCL8576BP-D AGERE [Agere Systems], LUCL8576BP-D Datasheet - Page 22

• Manufacturer Part Number: LUCL8576BP-D
• Description: Dual Ringing SLIC
• Manufacturer: AGERE [Agere Systems]

L8576B Dual Ringing SLIC
Applications
ac Design
Transmit Gain
Transmit gain will be specified as a gain from T/R to
PCM, T
assumed to be 0 dB, and in the case of T/R being refer-
enced to some complex impedance other than 600
resistive, the effects of the impedance transformation
must be taken into account.
Again specified complex termination impedance at T/R
is of the form:
First calculate the equivalent resistance of this network
at the midband frequency of 1000 Hz.
R
Using R
into account the impedance transformation:
T
22
X
EQ
---------------------------------------------------------------------------- -
2
(dB) = T
=
f
1
Figure 21. ac Interface Circuit Using First-Generation Codec (Blocking Capacitors Not Shown)
X
2
EQ
+
C
(dB). Since PCM is referenced to 600
, calculate the desired transmit gain, taking
1 2
2
X (specified[dB])
R
(continued)
–I
f
1
195
R
2
T/R
R
2 2
(continued)
2 2
R
+
1
C
R
1 2
1
+ 20log
+
R
R
TGP
2
R
C
R
2
2
AX
RCVN
RCVP
TGS
= 24.4 k
+
---------- -
R
-------------------------------------------------- -
1
600
C
EQ
+
TGS
2
2
f
R
f
V
2 2
ITR
2
R
C
2 2
1
C
1 2
5-6396(F)
and
2
T
impedance at the PCM and R
the T/R. 20log
due to the impedance transformation.
Note in the case of a 600
at T/R 20log
Thus, there is no power loss/gain due to impedance
transformation and T
Finally, convert T
T
The ratio of R
with a dual Agere codec such as T8503
R
----------
R
R
X (specified[dB])
X
X
R
R
T2
X
(dB) = 20log G
< 200 k
N1
N2
= G
C
N
TX
x
195
--------- -
is the specified transmit gain. 600
R
R
X
M
---------- -
R
/R
600
T1
GP
R
R
EQ
---------- -
R
600
T2
RCV
X
T2
TX
EQ
(dB) to a ratio, G
is used to set the transmit gain:
= 20log
X
represents the power loss/gain
(dB) = T
R
HB
–
+
R
OP AMP
CODEC
pure resistive termination
x
EQ
600
--------- -
600
X (specified[dB])
is the impedance at
CODEC
OUTPUT
DRIVE
AMP
= 0.
TX
Agere Systems Inc.
:
.
May 2001
5-6400a(F)
is the