LUCL9310AP-D AGERE [Agere Systems], LUCL9310AP-D Datasheet - Page 36

• Manufacturer Part Number: LUCL9310AP-D
• Description: Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device
• Manufacturer: AGERE [Agere Systems]

Full-Feature SLIC, Ringing Relay, and Test Access Device
Applications
dc Characteristics
Overhead Voltage (continued)
The TESTSIG and RCV inputs will not overload with an
input signal swing betwen ground and V
However, the SLIC output saturation point (at PT/PR) is
a function of the device overhead. Default overhead
with OVH = 0 is 3.14 dBm into 900 . After that, output
signal swing increases 1 V for every volt that overhead
is increased.
Overhead voltage may need to be increased to accom-
modate on-hook transmission of higher-voltage sig-
nals, such as meter pulse. The following example is
meant to illustrate the design procedure that can be fol-
lowed.
Assume that an on-hook transmission of a 2.2 Vrms
meter pulse into 200
50
V
V
V
Adding 0.5 V for tolerance, the overhead needs to be
increased to (8.662 + 0.5) 9.16
undistorted on-hook transmission of a 2.2 Vrms meter
pulse into 200 .
The overhead is set with respect to battery voltage and
during a test mode, the battery voltage is unknown.
With zero voltage on RCV input, the output is battery
voltage minus the overhead on the input, which is the
main offset. The small RCV input offset that is multi-
plied by RCV gain to tip/ring output is inconsequential.
Loop Range
The dc loop range is calculated using:
R
V
being calculated. The loop resistance value where the
device automatically switches to V
the Automatic Battery Switch section of this data sheet.
Battery Feed
The L9310 operates in a dc unbalanced mode. In the
forward active state, under open circuit (on-hook) con-
ditions, with the default overhead chosen, the tip to ring
voltage will be a nominal 5.5 V less than the battery.
This is the overhead voltage. The tip and ring overhead
is achieved by biasing ring a nominal 3.5 V above bat-
tery and by biasing tip a nominal 2.0 V below ground.
36
OH
OH
OH
BAT1
L
=
= 4.0 V + (1+ (2 x Rp)/200) x Vpeak
= 4.0 + (1+ (2 x 50)/200) x 2.2 (1.414)
= 8.662 V
protection resistors are used.
is used because the maximum loop range is
----------------------------------
V
BAT
I
LOOP
–
V
OH
(continued)
– 2R
(continued)
is needed. Further assume
P
– R
dc
9.2 V to allow for an
BAT2
is calculated in
CC
– 0.5 V.
During off-hook conditions, some dc resistance will be
applied to the subscriber loop as a function of the phys-
ical loop length, protection, and telephone handset. As
the dc resistance decreases from infinity (on-hook) to
some finite value (off-hook), the tip to ring voltage will
decrease as shown in Figure 13.
As illustrated in Figure 13, 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
Refer to Figure 13 and Figure 14 in this section and to
Figure 12 in the Automatic Battery Switch section.
VRING TO GND
LOOP
LOOP
V
T/R
T/R
OH
LOOP
P
dc
VTIP TO GND
BAT
= protection resistance.
= SLIC internal dc feed resistance.
= overhead voltage.
=
= dc loop voltage.
=
= dc loop current.
= loop resistance, including wire and handset
--------------------------------------------------------------- -
------------------------------------------------------
R
= battery voltage magnitude.
V
V
R
BAT
LOOP
BAT
LOOP
V
Figure 13. Tip/Ring Voltage
BAT
–
+
+
V
2R
(1/2)R
(1/2)R
–
OH
2R
V
P
BEGIN CURRENT LIMITING
OH
P
dc
dc
+
+
R
R
R
LOOP
). The ring to ground voltage
dc
dc
DECREASING LOOP LENGTH
Agere Systems Inc.
July 2001
(1/2)R
12-3431a (F)
dc
+ R
LIM