LUCL9310AP-D AGERE [Agere Systems], LUCL9310AP-D Datasheet - Page 53

• Manufacturer Part Number: LUCL9310AP-D
• Description: Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device
• Manufacturer: AGERE [Agere Systems]

July 2001
ac Applications
First-Generation Codec ac Interface Network: Complex Termination
Blocking Capacitors
Figure 18. ac Interface Using First-Generation Codec (Including Blocking Capacitors) for Complex
If a 5 V only codec such as the Agere T7504 is used,
dc blocking capacitors must be added as shown in Fig-
ure 18. This is because the codec is referenced to
2.5 V and the SLIC to ground—with the ac coupling, a
dc bias at T/R is eliminated and power associated with
this bias is not consumed.
Typically, values of 0.1 µF to 0.47 µF capacitors are
used for dc blocking. The addition of blocking capaci-
tors will cause a shift in the return loss and hybrid bal-
ance frequency response toward higher frequencies,
degrading the lower-frequency response. The lower
Agere Systems Inc.
Termination Impedance
324.5
–I
T/R
(continued)
R
TGP
R
RCVN
RCVP
TGS
= 6.34 k
C
GS
Full-Feature SLIC, Ringing Relay, and Test Access Device
V
TX
0.1 F
T
XI
V
REF
the value of the blocking capacitor, the more pro-
nounced the effect is, but the cost of the capacitor is
lower. It may be necessary to scale resistor values
higher to compensate for the low-frequency response.
This effect is best evaluated via simulation. A PSPICE
model for the L9310 is available.
Design equation calculations seldom yield standard
component values. Conversion from the calculated
value to standard value may have an effect on the ac
parameters. This effect should be evaluated and opti-
mized via simulation.
R
R
15
N1
N2
C
N
V
ITR
V
REF
R
R
R
R
T3
GP
T6
RCV
C
R
C
B1
HB
B2
(continued)
–
+
OUTPUT
OP AMP
CODEC
CODEC
DRIVE
AMP
R
x
2.5 V
5-6401.K (F)
53