L3037FN datasheet(7/22 Pages) STMICROELECTRONICS

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TIP OPEN MODE (TO)

This mode is selected when the SLIC is adopted

in a system using the Ground start feature. In this

mode the TIP termination is set in High Impedan-

ce (100Kohm) while the RING termination is acti-

ve and fixed at Vbat + 4.5V. In the case of con-

nection of RING termination to GND the sinked

current is limited to 30mA. When RING is connec-

ted to GND both off-hook and ground-key detec-

tors become active.

Power dissipation in this mode with a -48V battery

voltage is 100mW (including the power dissipa-

tion from +5/-5V supply).

POWER DOWN MODE (PD)

In this mode, both TIP and RING terminations are

open and no current is fed into the line.

The power dissipation is very low.

This mode is usually selected in emergency con-

dition or when the connected line is disabled.

This is also the mode into which the SLIC is auto-

matically forced, in the case of thermal overload

Tj > 150

°C typ.

RINGING MODE (RNG)

When this mode is selected the ringing signal is

injected on the line via the ext relay activated by

the L3037 relay driver.

When the ringing signal phase is provided at the

RGIN pin, the relay command is also synchroni-

zed with the ringing signal zero crossing.

The TIP and RING termination of the L3037 are

senses the line current which is then integrated

on the CRT capacitor.

TIP pin voltage is fixed at – 2.5V, RING pin volt-

age is fixed at VBAT + 4.5V, TIP, RING buffer cur-

rent capability is limited to 100mA.

When off-hook occurs during ringing burst the

voltage on CRT increase above a proper thre-

shold and ring trip is detected.

Once ring trip is detected the ringing signal is

automatically disconnected at the first zero cros-

sing. When the ringing signal phase is not provi-

ded at the RGIN pin the ringing signal is discon-

nected immediately after ring trip detection.

EXTERNAL COMPONENTS LIST

To set the SLIC into operation the following para-

meters have to be defined:

- The DC feeding resistance ”Rfeed” defined as

the resistance of

the

traditional feeding

system (most common Rfeed values are:

400, 800, 1000 ohm).

- The AC SLIC impedance at line terminals ”Zs” to

which the return loss measurements is referred.

It can be real (typ. 600ohm) or complex.

- The equivalent AC impedance of the line ”Zl”

used for evaluation

of the trans-hybrid loss

performance (2/4wire conversion). It

is usu-

ally a complex impedance.

- The value of the two protection resistors Rp in

series with the line termination.

- The line impedance at the TTX freq. Zlttx.

- The reverse polarity transition time defined as

”

∆VTR/∆T”.

Once, the above parameters are defined, it is

possible to calculate all the external components

using the following table.

The typical values has been obtained supposing:

- Rfeed = 400

Ω

- Zs = 600

Ω

- Zl = 600

Ω

-Rp = 40

Ω

- Zlttx = 216

Ω + 120nF @ 12KHz

- Re[Zlttx] = 216

Ω

- Im[Zlttx] = -110

Ω @12KHz

∆VTR/∆T = 4250[V/s]

CONTROL INTERFACE

INPUTS

OPERATING MODE

OUTPUTS

GST

LIM

ODET

OGK

X (*)

POWER DOWN

STANDBY D. P.

STANDBY R. P.

ACTIVE D. P.

ACTIVE R. P.

RING

A. OPEN

RESERVED

DISABLE

OFF/HK

RING-TRIP

OFF/HK

–

DISABLE

GDKEY

DISABLE

GDKEY

–

(*) LIM = 0

→ Ilim = 25mA; LIM = H. I. (open) → Ilim = 44mA; LIM = 1 → Ilim = 55mA.

L3037

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