LUCL9215AAU-D AGERE [Agere Systems], LUCL9215AAU-D Datasheet - Page 36

• Manufacturer Part Number: LUCL9215AAU-D
• Description: Short-Loop Sine Wave Ringing SLIC
• Manufacturer: AGERE [Agere Systems]

Short-Loop Sine Wave Ringing SLIC
ac Applications
Design Examples
First-Generation Codec ac Interface Network—
Resistive Termination (continued)
This is a lower feature application example and uses
single battery operation, fixed overhead, current limit,
and loop closure threshold.
Resistor R
match of input bias voltage at the RCVN/RCVP inputs.
If it is not used, there may be a slight offset at tip and
ring due to mismatch of input bias voltage at the
RCVN/RCVP inputs. It is very common to simply tie
RCVN directly to ground in this particular mode of oper-
ation. If used, to calculate RGN, the impedance from
RCVN to ac ground should equal the impedance from
RCVP to ac ground.
Example 1, Real Termination
The following design equations refer to the circuit in
Figure 22. Use these to synthesize real termination
impedance.
Termination Impedance:
36
V
S
Z
T/R
Z
z
T
T
GN
+
–
=
I
V
T/R
R
R
is optional. It compensates for any mis-
T/R
P
50
P
RING
TIP
+
(continued)
z
(continued)
2
T
R
=
P
CURRENT
------------
–
V
+
SENSE
I
18
T/R
18
T/R
---------------------------------- -
1
+
-------- -
R
R
2400
G P
T 1
+
Figure 22. ac Equivalent Circuit
----------- -
R
R
R CV
T1
A
A
V
V
= –1
= 1
–
+
+
–
–0.300 V/mA
L9215
A
V
= 4
Receive Gain:
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 the following:
VITR
+
–
RCVN
RCVP
g
g
rcv
rcv
R
h
GP
=
bal
=
R
R
H B
------------------------------------------------------------------
V
----------- -
R
V
= 20log
R
T1
1
h
RCV
T2
T/R
FR
R
bal
g
+
k
HB1
t x
R
-----------
= 20log
g
R
R CV
tx
=
T1
=
=
–
-------- -
R
----------- -
R
R
R
------------------ -
g
+
T2
V
---------- -
HB
V
X
tx
X
R
----------- -
GSX
R
T/R
R
8
R C V
–
V
-------------- -
G P
V
V
VF
VF
X
-------- -
Z
300
g
g
GSX
FR
FR
T/R
rcv
tx
X
X
September 2001
IN
IP
1/4 T7504 CODEC
Agere Systems Inc.
1
g
–
+
R
rcv
+
X
+2.4 V
-------- -
Z
Z
T/R
T
12-2554.V (F)
VGSX