LUCL9218AAR-D AGERE [Agere Systems], LUCL9218AAR-D Datasheet - Page 21

• Manufacturer Part Number: LUCL9218AAR-D
• Description: Low-Cost Line Interface
• Manufacturer: AGERE [Agere Systems]

Data Sheet
November 2001
Agere Systems Inc.
Applications
dc Applications
Ring Trip Detection
The ring trip circuit is a comparator that has a special input section optimized for this application. The equivalent
circuit is shown in Figure 15, along with its use in an application using unbalanced, battery-backed ringing.
Ring trip detection threshold is given by the following equation:
Longitudinal Balance
The SLIC is graded to certain longitudinal balance specifications. The numbers are guaranteed by testing (Figure
5 and Figure 8). However, for specific applications, the longitudinal balance may also be determined by termination
impedance, protection resistance, and especially by the mismatch between protection resistors at tip and ring. This
can be illustrated by the following equation:
LB = 20 x log
where:
LB: longitudinal balance.
RP: protection resistor value in .
ZT: magnitude of the termination impedance in .
The
longitudinal balance specification on a specific code.
Now with
Be aware that ZT may vary with frequency for complex impedance applications.
: protection resistor mismatch in .
: SLIC internal tip/ring sensing mismatch.
can be calculated using the above equation with these exceptions:
available, the equation will predict the actual longitudinal balance for RP, ZT, and .
------------------------------------------------------------------------------------------ -
368
368 RP
(continued)
(continued)
+
2
Figure 15. Ring Trip Equivalent Circuit and Equivalent Application
I
TH
ZT 2
(mA) =
–
V
RC PHONE
368 ZT RP
HOOK SWITCH
BAT
PHONE
+
RP
------------------------------------------------------------------------------------------------------------------------------------------------------------------------ -
V
RTSN M
RING
R
–
LOOP
+
R
402
S
3.32 M 3.40 M
+
0.015 RTSP M
2.94 M
510
R
RTSN M
R
TSN
TSP
–
C
0.015 F
RTS1
R
R
+
TSN
TSP
0.015
+
–
I
15 k
P
L9218A/G Low-Cost Line Interface
= I
I
N
N
V
R
BAT
S
+
–
0, ZT = 600
–
8.6 V
8.6
NSTAT
1000
RP = 100
and the
2799 (F)
21