LUCL9312AP-D AGERE [Agere Systems], LUCL9312AP-D Datasheet - Page 27

• Manufacturer Part Number: LUCL9312AP-D
• Description: Line Interface and Line Access Circuit Forward Battery SLIC and Ringing Relay for TR-57 Applications
• Manufacturer: AGERE [Agere Systems]

July 2001
Applications
dc Characteristics
Battery Feed (continued)
As illustrated in Figure 12, as loop length decreases,
the tip to ground voltage will decrease with a slope cor-
responding to one-half the internal dc feed resistance
of the SLIC (typical 75
will also decrease with a slope corresponding to one-
half the internal dc feed resistance of the SLIC, until the
SLIC reaches the current-limit region of operation. At
that point, the slope of the ring to ground voltage will
increase to the sum of one half the internal dc feed
resistance plus approximately 10 k .
The dc feed characteristic can be described by:
I
V
Where:
I
V
V
R
resistance.
R
R
Notes:
V
V
I
Agere Systems Inc.
LIM
LOOP
LOOP
BAT1
BAT2
V
T/R
T/R
OH
LOOP
P
dc
Figure 13. L9312 Loop Current vs. Loop Voltage
BAT
= 40 mA (R
= protection resistance.
= SLIC internal dc feed resistance.
= overhead voltage.
=
= dc loop voltage.
= –48 V.
= –24 V.
50
40
30
20
10
=
= dc loop current.
0
= loop resistance, including wire and handset
--------------------------------------------------------------- -
0
= battery voltage magnitude.
------------------------------------------------------
R
V
R
LOOP
BAT
LOOP
V
5
PROG
BAT
–
+
V
+
2R
10
= 66.5 k ).
–
OH
2R
(continued)
V
P
OH
P
+
15
+
LOOP VOLTAGE (V)
R
R
(continued)
R
LOOP
). The ring to ground voltage
dc
dc
20
10 k
1
25
Forward Battery SLIC and Ringing Relay for TR-57 Applications
30
35
40
12-3050.g (F)
R
1
dc
45
Refer to Figure 12 and Figure 13 in this section and to
Figure 11 in the Automatic Battery Switch section.
Starting from the on-hook condition and going through
to a short circuit, the curve passes through two regions:
Region 1: on-hook and low loop currents: the slope cor-
responds to the dc feed resistance of the SLIC (plus
any series resistance). The open-circuit voltage is the
battery voltage less the overhead voltage of the device.
Region 2: current limit: the dc current is limited to a
value determined by V
plate has a high resistance (10 k ).
Notice that the I-V curve is uninterrupted when the
power is shifted from the high-voltage battery to the
low-voltage battery (if auxiliary battery option is used).
This is shown in Figure 11 in the Automatic Battery
Switch section.
Longitudinal to Metallic Balance
Longitudinal to metallic balance at PT/PR is specified in
the Electrical Characteristics section of this data sheet.
Supervision
Loop Closure
Loop closure supervision threshold is programmed via
an applied voltage source or ground, through a resistor
at the LCTH input. Loop closure status is presented at
the NSTAT output. NSTAT is an unlatched output that
represents either the loop closure or ring trip status,
depending on the device state. See Table 2 for more
details. Loop closure threshold current (I
where:
R
voltage source.
V
There is a built-in hysteresis associated with the loop
closure detector. The above equation describes the on-
hook to off-hook threshold. To help prevent false
glitches, the off-hook to on-hook threshold will be a typ-
ical 20% lower than the corresponding on-hook to off-
hook threshold.
250 V
-------------------------------------------------- -
LCTH
LCTH
R
LCT H
is ground or an external voltage source.
is a resistor from the LCTH node to ground or a
REF
–
k
V
LC TH
= I
PROG
LCTH
. This region of the dc tem-
(mA)
LCTH
) is set by:
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