LUCL9218AAR-D AGERE [Agere Systems], LUCL9218AAR-D Datasheet - Page 20

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

L9218A/G Low-Cost Line Interface
Applications
dc Applications
Loop Range
The equation below can be rearranged to provide the loop range for a required loop current:
Off-Hook Detection
The loop closure comparator has built-in longitudinal rejection, eliminating the need for an external 60 Hz filter. The
loop closure detection threshold is set by resistor R
condition. The off-hook comparator goes low during an off-hook condition:
20
20
(continued)
(continued)
I
I
TR
TR
(mA) = 0.4167 R
(mA) = 0.4167 R
R
L
Figure 14. Off-Hook Detection Circuit
ITR
R
R
R
P
P
L
RING
LCTH
LCTH
=
TIP
--------------------------- -
V
(k ) – 1.9 mA ACTIVE off-hook to on-hook
(k ) + 2.7 mA SCAN on-hook to off-hook
B A T
LCTH
+
–
I
L
–
0.05 mA
. The supervision output bit NSTAT is high in an on-hook
V
0.125 V/mA
O H
–
2R
P
–
+
–
R
D C
LCTH
NSTAT
DCOUT
R
LCTH
November 2001
Agere Systems Inc.
Data Sheet
12-2553 (F).f