Fig 1 : Topologyof the classical line card protection.

APPLICATION INFORMATION

Fig 2 : Classical use of the SSRP130B1.

The classical line card requires protection before

the ring relay and a second one for the SLIC (fig.1).

The use of new SLICs with integrated ring

generator or board based on solid state ring relay

suppresses this second protection (Fig. 2). Then

the only remaining stage, located between the line

and the ring relay, has to optimize the protection.

The classical symmetrical first stage protector

becomes not sufficient to avoid any circuit

destruction during surges.

The SSRP130B1 device takes into account this

fact and is based on asymmetrical voltage

characteristics (Fig.3a). The ring signal being

shifted

back

by

the

battery

voltage,

the

SSRP130B1 negative breakover value Vbo- is

greater than the positive one Vbo+. This point

guarantees a protection operationvery close to the

peak of the normal operating voltage without any

disturbance of the ring signal.

Fig 3 : SSRP130B1 electrical characteristics.

I

V

Vbo-

Vbo+

a : Line to ground characteristics.

b : Line to line characteristics.

In addition with the 2 crowbar functions which

perform the protection of both TIP and RING lines

versus ground, a third cell assumes the differential

mode protection of the SLIC. The breakdown

voltage values of this third cell are the same for

both

positive

and

negative

parts

of

the

characteristics and are equivalent to the negative

breakdown voltage value of the TIP and RING

lines versus GND cells (Fig.3 b).

PTC

PTC

R

R

SLIC

SSRP130B1

Tip

Ring

(*)

(*) SLIC with integrated ring generator or solid state relay.

LINE

1st

stage

2nd

stage

PTC

PTC

R

R

SLIC

Ring generator

Line

Tip

Ring

SSRP130B1

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