LUCL9500AGF-DT datasheet(23/32 Pages) AGERE

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Preliminary Data Sheet

September 2001

High-Voltage Ringing SLIC for VoIP Applications

L9500A

Agere Systems Inc.

Applications (continued)

Battery Reversal Rate

The rate of battery reverse is controlled or ramped by

capacitors FB1 and FB2. A chart showing FB1 and FB2

values vs. typical ramp time is given below. Leave FB1

and FB2 open if it is not desired to ramp the rate of bat-

tery reversal.

Table 20. FB1 and FB2 Values vs. Typical Ramp

Time

Supervision

The L9500 offers the loop closure and ring trip supervi-

sion functions. Internal to the device, the outputs of

these detectors are multiplexed into a single package

output (NSTAT). The ring trip detector is valid on

NSTAT during the ring mode and loop closure detector

is valid on NSTAT during active and on-hook transmis-

sion modes. Additionally, common-mode current is

detected for ground start applications. This status is

output onto NSTAT and is valid during ground start

mode.

Loop Closure

The loop closure has a fixed typical 10.5 mA on- to off-

hook threshold in the active mode and a fixed 11.5 mA

on- to off-hook threshold from the scan mode. In either

case, there is a 2 mA hysteresis with VCC = 5 V and a

2 mA hysteresis with VCC = 3.3 V.

Ring Trip

The ring trip detector requires only a single-pole filter at

the input, minimizing external components. An R/C

combination of 383 k

Ω and 0.1 µF, for a filter pole at

5.15 Hz, is recommended.

The ring trip threshold is internally fixed as a function of

battery voltage and is given by:

RT (mA) = 67 * {(0.0045 * VBAT1) + 0.317}

where:

RT is ring trip current in mA.

VBAT1 is the magnitude of the ring battery in V.

There is a 6 mA to 8 mA hysteresis.

Ground Start

In the ground start applications, the loop closure detec-

tor detector is also used to indicate that ring-ground

has occurred. During ground start mode, loop current

will be common mode, rather than differential as in loop

start mode. Thus, in ground start the threshold of the

loop closure detector is reduced by one half the thresh-

old seen in the loop start mode.This ouput is seen at

the NSTAT output pin.

CFB1 and CFB2

Transition Time

0.01

µF

20 ms

0.1

µF

220 ms

0.22

µF

440 ms

0.47

µF

900 ms

1.0

µF

1.8 s

1.22

µF2.25 s

1.3

µF

2.5 s

1.4

µF

2.7 s

1.6

µF

3.2 s

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