DESCRIPTION

Circuit description

The L3235 Subscriber Line Interface Circuit

(SLIC) is a bipolar integrated circuit in 60V tech-

nology optimized for PABX application.

The L3235 supplies a line feed voltage with a cur-

rent limitation which can be modified by an exter-

nal resistor (RLIM).

The SLIC incorporates loop currents, ground key

detection functions with an externally programma-

ble constant time.

The two to four wires and four to two wires voice

frequency signal conversion is performed by the

L3235 and the line terminating and the balancing

impedances are externally programmable.

The device integrates an automatic power limita-

tion circuit. In short loop condition the extra power

is dissipated on one external transistor (Text).

This aproach allows to assembly the L3235 in a

low cost standard plastic PLCC28 package.

The chip is prote cted by thermal protection at

Tj = 150

°C.

The SLIC is able to give a power up command for

Combo in off hook condition and an enable logic

for solid state ringing injector L3234.

The L3235 package is 28 pin plastic PLCC.

The L3235 has been designed to operate

togheter

with

L3234

performing

complete

BORSHT function without any electromechanical

ringing relay (see the application circuit fig. 16).

PLCC28

L3235

Subscriber Line Interface Circuit

PIN CONNECTION

ABSOLUTE MAXIMUM RATINGS

Symbol

Parameter

Value

Unit

Battery Voltage

-54

V

Positive Supply Voltage

5.5

V

Negative Supply Voltage

-5.5

V

Max. Junction Temperature

150

°C

Storage Temperature

-55 to +150

°C

OPERATING RANGE

Symbol

Parameter

Min.

Max.

Unit

Battery Voltage

-52

-24

V

Positive Supply Voltage

4.75

5.25

V

Negative Supply Voltage

-5.25

-4.75

V

Operating Temperature for L3235

L3235T

0

-40

70

85

°C

°C

Max Junction Operating Temperature

130

°C

Note: Operating ranges define those limits between which the functionality of the device is guaranteed.

L3234 - L3235

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