LUCL9312AP-D AGERE [Agere Systems], LUCL9312AP-D Datasheet - Page 5

• 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
Description
The switch point is a function of the user-programmed
dc current limit and the magnitude of the auxiliary bat-
tery. Switching from the high-voltage to low-voltage
battery is quiet, without interruption of the dc loop cur-
rent, thus preventing any impulse noise generation at
the switch point. Design equations for the switch point
and a graph showing loop/battery current versus loop
resistance are given in the dc Characteristics in the
Applications section of this data sheet.
If the user does not want to provide an auxiliary battery,
the design of the L9312 battery switch allows use of a
power control resistor at the auxiliary battery input. This
scheme will not reduce short-loop, off-hook power dis-
sipation, but it will control power dissipation on the
SLIC by sharing power among the SLIC, power resis-
tor, and dc loop. However, in most cases, without the
auxiliary battery, the power dissipation capabilities of
the 44-pin PLCC package are adequate so that the
power control resistor will not be needed. Design equa-
tions for power control options are given in the dc Char-
acteristics section of this data sheet.
The L9312 is a forward battery only SLIC that supports
on-hook transmission.
A low-power scan mode is available to reduce idle
mode on-hook power. This mode is realized by using a
scan clamp circuit. In low-power scan mode:
A forward disconnect mode, where all circuits are
turned off and power is denied to the loop, is also pro-
vided. During this mode, the NSTAT supervision output
will read on-hook.
In the ring mode, the line break switches are opened
and the power ring access switches are closed. In this
mode, the ring trip detector in the SLIC is active and all
other detectors and the tip/ring drive amplifiers are
turned off to conserve power.
Make-before-break or break-before-make switching is
achievable during ring cadence or ring trip. Toggling
directly into or directly out of the ring mode table will
give make-before-break switching. To achieve break-
before-make switching, go to an intermediate all-off
state (use forward disconnect state) before entering the
ring mode or before leaving the ring mode. See the
Agere Systems Inc.
The scan clamp circuitry is active.
Loop closure is active.
All ac transmission, dc feed, and other supervision
circuits, including ring trip, are shut down.
Thermal shutdown is active.
Low battery sense shutdown is on.
On-hook transmission is disabled.
(continued)
Forward Battery SLIC and Ringing Relay for TR-57 Applications
Switching Behavior section of this data sheet for more
details on switching behavior.
Voltage transients or impulse noise associated with
ring cadence or ring trip are minimized or eliminated
with the L9312, thus possibly eliminating the need for
external zero-cross switching circuitry.
Both the ring trip and loop closure supervision func-
tions are included. Loop closure threshold is set by
applying a voltage source to the LCTH input. The volt-
age source may be an external voltage source or
derived from the SLIC V
external voltage source may be used to provide soft-
ware control of the loop closure threshold. Design
equations for the loop closure threshold are given in
the Supervision section of this data sheet. Hysteresis is
included.
The ring trip detector requires only a single-pole filter at
the input. This will minimize the required number of
external components. To help minimize device power
dissipation, the ring trip detector is active only during
the power ring mode.
Ring trip and loop supervision status outputs appear in
a common output pin, NSTAT. NSTAT is an unlatched
supervision output; thus, an interrupt-based control
scheme may be used.
The dc current limit is set in the active modes via an
applied voltage source. The voltage source may be an
external voltage source. The voltage may be derived
via a resistor divider network from the V
put. A programmable external voltage source may be
used to provide software control of the loop closure
threshold. Design equations for this feature are given in
the dc Characteristics section of this data sheet. Pro-
gramming range is 10 mA to 45 mA.
Overhead is programmable in the active modes via an
applied voltage source. The voltage source may be an
external voltage source or derived via a resistor divider
network from the V
A programmable external voltage source may be used
to provide software control of the overhead voltage.
The rate of change of the overhead voltage may be
controlled by use of a single external capacitor at the
C
may be audible noise associated with this transition.
Design equations for this feature are given in the dc
Characteristics section of this data sheet.
If the overhead is not programmed via a resistor, the
device develops a default overhead adequate for a
3.14 dBm overload into 900 . For the default over-
head, OVH is connected to ground.
F1
node. If the rate of change is uncontrolled, there
REF
SLIC output.
REF
output. A programmable
REF
SLIC out-
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