Data Sheet
July 2001
L9310 Line Interface and Line Access Circuit
Full-Feature SLIC, Ringing Relay, and Test Access Device
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:
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Description
(continued)
The second chip is manufactured in Agere dielectrically
isolated 320 V bipolar CMOS diffused metal oxide
semiconductor (BCDMOS III) technology. This chip
contains the following:
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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.
PPM and test are powered down.
Thermal shutdown is active.
Low battery sense shutdown is on.
On-hook transmission is disabled.
Ring access relay
Scan clamp circuitry
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Logic control
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Ring trip
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Test
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PPM
Thermal shutdown
Battery monitor circuit
The LILAC family requires a +5 V and battery supply to
operate. No –5 V supply is required. A battery switch is
included that automatically, based on subscriber loop
length, will apply either the primary higher-voltage bat-
tery or an optional lower-voltage auxiliary battery. Use
of this feature will minimize off-hook power dissipation.
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 section of
this data sheet.
If the user does not want to provide an auxiliary battery,
the design of the L9310 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 L9310 has two active transmission ready states,
forward active and reverse active. Both on-hook and
off-hook transmission are provided during the forward
and reverse battery modes. Battery reversal is quiet,
without breaking the ac path. Rate of battery reversal
may be ramped to control switching time via optional
external capacitors. Equations relating rate of battery
reversal to these optional external capacitors are given
in the dc Characteristics, Power Control section of this
data sheet.
Agere Systems Inc.
When the scan clamp circuitry is on, overhead voltage
is fixed and not controlled by OVH. When the scan
clamp is on, current limit is not controlled by V
PROG
;
rather, it is set by the internal capabilities of the scan
clamp circuit. See the dc Loop Current Limit and Over-
head Voltage sections of this data sheet for more
details.
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
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 L9310, thus possibly eliminating the need for
external zero-cross switching circuitry.
A tip open switch configuration is also available for
ground start applications. A common-mode current
detector is included for ground start and ground key
applications.
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