LUCL9311AP-D AGERE [Agere Systems], LUCL9311AP-D Datasheet - Page 43

• Manufacturer Part Number: LUCL9311AP-D
• Description: Line Interface and Line Access Circuit Full-Feature SLIC with High Longitudinal Balance, Ringing Relay,and GR-909 Test Access
• Manufacturer: AGERE [Agere Systems]

July 2001
ac Applications
First-Generation Codec ac Interface Network: Resistive Termination
Example 1, Real Termination
The following design equations refer to the circuit in
Figure 15. Use these to synthesize real termination
impedance.
Termination Impedance:
Receive Gain:
Agere Systems Inc.
V
S
Z
T/R
Z
Z
g
g
T
rcv
T
rcv
+
–
=
I
V
T/R
R
=
R
=
T/R
P
76
P
RING
------------------------------------------------------------------
V
----------- -
V
TIP
1
T/R
FR
+
+
R
-----------
R
SWITCH
SWITCH
Z
BREAK
BREAK
(continued)
R C V
2
T
T 3
18
18
R
=
P
+
+
V
------------
–
I
R
----------- -
T/R
T/R
---------------------------------- -
1
R
8
R C V
CURRENT
G P
+
SENSE
-------- -
R
R
20
20
2400
G P
T 3
1
+
+
----------- -
R
Figure 15. ac Equivalent Circuit
-------- -
Z
R
Z
R C V
T/R
T3
T
A
A
V
V
= 1
= –1
–0.300 V/mA
L9311
A
V
= 4
Transmit Gain:
Hybrid Balance:
To optimize the hybrid balance, the sum of the currents
at the VFX input of the codec op amp should be set to
0. The expression for ZHB becomes:
VITR
–
+
Ringing Relay, and GR-909 Test Access
RCVN
RCVP
V
REF
V
REF
h
bal
R
R
R
GP
H B
= 20 log
R
R
T3
h
RCV
T6
bal
R
k
HB1
g
t x
= 20 log
g
=
tx
=
(continued)
–
-------- -
-------------- -
R
=
R
------------------ -
g
R
R
H B1
T 6
t x
V
---------- -
V
X
X
R
GSX
T/R
V
-------------- -
VFR
VF
VF
–
X
V
g
-------- -
Z
300
GSX
g
FR
rcv
X
X
T/R
tx
IN
IP
1/4 T7504 CODEC
–
+
g
R
X
rcv
2.4 V
12-3580C (F)
VGSX
43