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LUCL9313AP

Line Interface and Line Access Circuit Full-Feature SLIC and Ringing Relay for TR-57 Applications

Agere -> LSI Corporation 

Data Sheet

September 2001

L9313 Line Interface and Line Access Circuit

Full-Feature SLIC and Ringing Relay for TR-57 Applications

Description (continued)

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

Application section of this data sheet.

If the user does not want to provide an auxiliary battery,

the design of the L9313 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 L9313 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.

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:

s The scan clamp circuitry is active.

s Loop closure is active.

s All ac transmission, dc feed, and other supervision

circuits, including ring trip, are shut down.

s Thermal shutdown is active.

s Low battery sense shutdown is on.

s On-hook transmission is disabled.

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.

Agere Systems Inc.

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 L9313, 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.

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 VREF output. A programmable

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 VREF SLIC out-

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 VREF SLIC output.

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