LUCL9312AP-D AGERE [Agere Systems], LUCL9312AP-D Datasheet - Page 30

• 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]

Forward Battery SLIC and Ringing Relay for TR-57 Applications
Protection
Active Mode Response at PT/PR
For a lower-voltage power cross, whose maximum
peak voltage is below the foldback voltage breakpoint 1
(V1), the current-limited break switch will pass the cur-
rent equal to the dc current limit. The current limit has a
negative temperate coefficient, so as the device contin-
ues to pass current, the current limit will reduce with
increasing device temperature. Ultimately, the device
will reach the thermal shutdown temperature and the
thermal shutdown mechanism will force an all-off state,
which will stop current flow and begin device cooling. In
the all-off state, the external protection device ensures
that the switch off-state voltage rating is not exceeded.
Once the device cools significantly, the break switches
will turn on, and current will begin to flow again, until
temperature forces the all-off state. This will continue
until the fault condition is gone.
Sneak-under surge is a voltage surge that is just below
the clamping threshold of the secondary protection
device. For this type of surge, when the surge voltage
is below the foldback voltage breakpoint 1, operation is
as described above. When the surge voltage rises
above the foldback voltage breakpoint 1 (V1), but is still
less than the secondary protector clamping voltage, the
line break switch will crowbar into the high-impedance
region of its I-V characteristic and reduce current to the
specified I
For surges whose magnitude range above the trigger
of the external secondary protector, the device will
operate as described above for the portion of the surge
below the secondary protector trigger voltage. When
the voltage rises above the external secondary protec-
tor’s trigger voltage, the secondary protector will crow-
bar on shunting fault current to ground and reducing
the tip/ring voltage seen at the device.
In the active mode, the external secondary protector
must ensure that the off-state voltage ratings of the ring
access and ring return switch are not exceeded. Nor-
mally, the ring return switch is connected to ground on
the TRING side and to the protector on the PT side;
thus, the protector on the tip side in the active mode
must clamp at less than 320 V. As will be seen in the
Ring Mode Response at PT/PR section, during the
power ringing mode, this clamp voltage on the tip side
is significantly less than 320 V.
Normally, the ring access switch is connected to the
ring generator on the RRING side and to the protector
on the PR side; thus, on one side of the switch there is
the battery voltage and the peak negative ring signal,
30
LIMIT
2 value.
(continued)
(continued)
and on the PR side, the maximum turn-on voltage of
the secondary protector. The ring access switch is of
pnpn construction. Thus, if the off-state voltage rating
of the ring access switch is exceeded, the device will
crowbar into a low-impedance state. This will cause a
surge into the ring generator and can cause the on-
state current rating of the switch to be exceeded.
The difference of the battery plus peak negative ring
signal voltage less the maximum turn on of the second-
ary protector must not exceed the off-state voltage rat-
ing of the ring access switch. Additionally, as the
secondary protector will see the power ring signal, the
minimum turn-on rating of the secondary protector
must be high enough to not clamp the ring signal and
cause clipping distortion. The ring side will see the full-
power ring voltage, and the tip side switch will see the
power ringing voltage that is attenuated by the ringing
load, subscriber loop, feed resistor, and protection
resistors; thus, the ring side secondary protector
requires a higher clamping voltage than the tip side.
Ring Mode Response at PT/PR
In this mode, the line break switches are off and the
ring access and ring return switch is on. The secondary
protectors must ensure that the minimum off-state volt-
age rating of the line break switches is not exceeded.
Note that the maximum differential voltage is the posi-
tive zener rating of the protection device less the bat-
tery voltage which will appear on the line feed side of
the switch.
The ring access switch is a pnpn type switch. This
switch has no internal current limiting. Thus, through
external current limit, the user must ensure that the
surge ratings (both dynamic and dc for lightning and
power cross faults) are not exceeded. A minimum
400
also will set the ring trip threshold. See the Ring Trip
section within the Supervision section of this data sheet.
During a lightning fault (typical 1000 V 10 x 700 s
applied surge), the current-limited tip return switch will
pass, typically 2.5 A for 0.5 s before forcing the switch
off. Once in the off state, the external protection device
must ensure that the off-state voltage rating of 320 V is
not exceeded.
ring feed resistor is recommended. This resistor
Agere Systems Inc.
July 2001