LUCL8574DP-D AGERE [Agere Systems], LUCL8574DP-D Datasheet - Page 30

• Manufacturer Part Number: LUCL8574DP-D
• Description: L8574D Resistive Subscriber Line Interface Circuit(SLIC), Ring Relay,and Protector(SRP)for Long Loop and TR-57 Applications
• Manufacturer: AGERE [Agere Systems]

L8574D Resistive Subscriber Line Interface Circuit (SLIC), Ring
Relay, and Protector (SRP) for Long Loop and TR-57 Applications
ac Design
Design Equations
The Tip/Ring differential current is given by:
The voltage at pin XMT is given by:
The component values in the ac interface of Figure 12
are calculated (for the transmit and receive gains
defined by the respective gain constants K
and for the termination impedance seen in Figure 11)
using the following equations:
30
R
1
Figure 12. Initial ac Interface for Complex Termination Between L8574 SLIC and T7504 Codec
R
C
2
1
Z
(continued)
T/R
I
T/R
V
Note: dc Blocking Capacitor (C
+
T/R
–
R
R
V
C
=
RV1
RV2
I
T/R
XMT
R
200 I
(continued)
RESISTOR
=
MODULE
=
=
200 k
200 k
=
K
------------------- -
100R
------------------ -
100R
------------------ -
RP
RCV
100
–
------------- -
K
K
V
RCV
RCV
–
2
V
100 k
T/R
C
BAT
---------- -
Z
V
1
2
100 k
IRP
RN
200
200
1 k
1 k
RX
TS
RS
PT
PR
and K
–
+
AX
RCV
V
B
BAT
) Not Shown, C
,
INTERFACE
1/2 L8574
RECEIVE
Note that the 200
the termination impedance. The termination impedance
associated with the circuit in Figure 12 consists of this
inherent 400
The negative and positive impedance terms are used
to adjust the termination impedance from the inherent
400
A negative impedance, where,
A positive impedance, where,
to any complex termination.
C
400
XMT
V
I
----------------------------- -
R
RP
T
T
RN
R
GX1
and C
=
R
GX
V
V
L
XMT
GX1
RN
RP
--------- - 1
100
R
= 2 x 200
+
C
feeding impedance in parallel with:
=
T2
R
R
R
Z
R
C
2
R
T1
+
T2
IRP
T1
T
Separate
feed resistors contribute 400
T2
x
------------- -
j C
+
=
K
--------- -
100
1
R
------------ - 1
=
2
R
R
TX
C
R
R
------------ -
T
GX1
100
RV1
R
GX1
T1
R
-------------- -
R
RV1
R
x
•
R
HB1
C
2
RV2
feed resistors
----------------------------- -
R
GX1
R
----------------------------- -
T
C
Lucent Technologies Inc.
GX1
--------- -
600
GX1
+
R
1
VFXIN
+
R
1/4 T7504 CODEC
100R
------------------ -
GX1
R
VFRO
+
R
T1
+
–
RV1
R
T1
--------
R
R
October 1998
1
T1
R
1
T1
1
–
+
GX
Data Sheet
+2.4 V
12-3429.b (F).r3
GSX
to