LUCL9313AP-D AGERE [Agere Systems], LUCL9313AP-D Datasheet - Page 32

• Manufacturer Part Number: LUCL9313AP-D
• Description: Line Interface and Line Access Circuit Full-Feature SLIC and Ringing for TR-57 Applications
• Manufacturer: AGERE [Agere Systems]

Full-Feature SLIC and Ringing Relay for TR-57 Applications
Protection
Ring Mode Response at PT/PR
For power cross for lower-voltage faults, the ring return
switch will behave like the line break switches. How-
ever, tip return switch does not have the foldback
clamping feature that is included in the line break
switches; thus, in the on state, the voltage seen by the
ring return switch before damage is less than the line
break switches. The on-state voltage of the line break
switches can go up to the off-state voltage rating. The
ring return voltage should see less than 130 V in the on
state. Thus, the secondary protector on the ring side
should have a maximum crowbar voltage of 130 V.
With typical protection device tolerance, this implies a
minimum clamping voltage of 100 V. The users should
ensure, based on minimum loop length, ringing load,
and peak ring signal voltage, that the ring signal is not
distorted by the (lower) voltage rating of the tip-side
protector.
Internal Tertiary Protection
The external secondary protector and switch current
limit protect the 320 V high-voltage switches from light-
ning and power cross conditions. Integrated into the
LILAC IC is an internal tertiary protection scheme that
is meant to protect the 90 V SLIC portion of the device
from residue fault current and voltages that may be
passed through the switches to the actual SLIC inputs.
This scheme includes an internal diode bridge voltage
clamp and a battery out of range detector that forces
an all-off condition if the battery voltage falls high or low
out of the specified operating range.
Diode Bridge
The internal inputs of the actual SLIC chip are clamped
to ground and to V
Residual positive fault currents are clamped to ground,
and residual negative fault currents are clamped to bat-
tery. This implies that the battery have some current-
sinking capability.
High common-mode currents, as may be seen under a
fault condition, will be sensed and reduced to zero by
the battery monitor circuit (see Battery Out of Range
Detector: High [Magnitude] section). However, this
detector will not prevent longitudinal current from flow-
ing into battery. The battery supply must have the abil-
ity to sink longitudinal currents as specified in the
longitudinal current capability requirement in Table 6.
32
(continued)
BAT1
by an integrated diode bridge.
(continued)
Battery Out of Range Detector: High (Magnitude)
This feature is useful in remote power applications
where a dc-dc converter with limited ability to sink cur-
rent is used as the primary battery supply. Under a fault
condition, the diode bridge will want to sink current into
the battery. As a function of the dc-dc converter input
capacitance and design, this current may cause the
magnitude of supply voltage to rise and ultimately
cause damage to the supply. To prevent damage to the
supply, the LILAC device will monitor the battery supply
voltage. If the magnitude of the battery rises above the
maximum specified operating battery, the battery out of
range detector will force the line break switches and
ring access switches into an all-off state, and will also
force the SLIC into the disconnect state. This will stop
the current flow into the battery, preventing damage to
the battery fault conditions. NSTAT is forced low during
this mode of operation.
Battery Out of Range Detector: Low (Magnitude)
The LILAC device will monitor the battery supply volt-
age. If the magnitude of the battery drops below the
minimum specified operating battery, the battery out of
range detector will force the line break switches and
ring access switches into an all-off state, and will also
force the SLIC into the disconnect state. NSTAT is
forced low during this mode of operation.
ac Applications
ac Parameters
There are four key ac design parameters. Termination
impedance is the impedance looking into the 2-wire
port of the line card. It is set to match the impedance of
the telephone loop in order to minimize echo return to
the telephone set. Transmit gain is measured from the
2-wire port to the PCM highway, while receive gain is
done from the PCM highway to the transmit port.
Transmit and receive gains may be specified in terms
of an actual gain, or in terms of a transmission level
point (TLP), that is, the actual ac transmission level in
dBm. Finally, the hybrid balance network cancels the
unwanted amount of the receive signal that appears at
the transmit port.
Codec Types
At this point in the design, the codec needs to be
selected. The interface network between the SLIC and
codec can then be designed. Following is a brief codec
feature summary.
September 2001
Agere Systems Inc.