L3121B

®

May 1999 - Ed:4A

PROGRAMMABLE TRANSIENT VOLTAGE

SUPPRESSOR FOR SLIC PROTECTION

SIP4

Application Specific Discretes

A.S.D.

TM

BIDIRECTIONAL FUNCTION WITH VOLTAGE

PROGRAMMABILITY IN BOTH POSITIVE AND

NEGATIVE POLARITIES.

PROGRAMMABLE BREAKDOWN VOLTAGE

UP TO 100 V.

HOLDING CURRENT = 150 mA min.

HIGH SURGE CURRENT CAPABILITY.

µs

FEATURES

This device has been especially designed to pro-

tect a subscriber line interface circuit (SLIC) with

an integrated ring generator.

Used with the recommended application circuit,

each line (TIP and RING) is protected against posi-

tive and negative surges. In the positive polarity,

the breakdown voltage is referenced to the + VB ,

and in the negative polarity, the breakdown voltage

is referenced to the -Vbat .

Its high surge current capability makes the L3121B

a reliable protection device for very exposed equip-

ment, or when series resistors are very low.

DESCRIPTION

CONNECTION DIAGRAM

Gate N

Gate P

GND

Line

SCHEMATIC DIAGRAM

1/7