LUCL9219AAR-D AGERE [Agere Systems], LUCL9219AAR-D Datasheet - Page 20

• Manufacturer Part Number: LUCL9219AAR-D
• Description: Low-Cost Line Interface with Reverse Battery and Dual Current Limit
• Manufacturer: AGERE [Agere Systems]

L9219A/G Low-Cost Line Interface
with Reverse Battery and Dual Current Limit
Applications
dc Applications
Rate of Battery Reversal
The rate of battery reversal is controlled or ramped by
capacitors FB1 and FB2. A chart showing FB1/FB2 val-
ues versus typical ramp rate is given below. Leave
FB1/FB2 open if it is not desired to ramp the rate of
battery reversal.
Table 12. FB1/FB2 Values vs. Typical Ramp Time
Loop Range
The equation below can be rearranged to provide the
loop range for a required loop current:
20
20
C
0.01 F
0.22 F
0.47 F
1.22 F
FB1
0.1 F
1.0 F
1.3 F
1.4 F
1.6 F
R
L
/C
=
FB2
--------------------------- -
V
(continued)
B A T
(continued)
I
L
–
V
O H
–
Transition Time
2R
220 ms
440 ms
900 ms
P
20 ms
2.25 s
1.8 s
2.5 s
2.7 s
3.2 s
–
R
D C
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
high in an on-hook condition. The off-hook comparator
goes low during an off-hook condition:
I
I
R
TR
TR
L
(mA) = 0.4167 R
(mA) = 0.4167 R
ITR
R
R
Figure 14. Off-Hook Detection Circuit
P
P
LCTH
off-hook to on-hook
on-hook to off-hook
RING
TIP
. The supervision output bit (NSTAT) is
LCTH
LCTH
+
–
0.05 mA
(k ) – 1.9 mA ACTIVE
(k ) + 2.7 mA SCAN
0.125 V/mA
November 2001
Agere Systems Inc.
+
–
Data Sheet
LCTH
NSTAT
DCOUT
12-2553 (F).f
R
LCTH