Obsolete

Product(s)

- Obsolete

Product(s)

Obsolete

Product(s)

- Obsolete

Product(s)

APPLICATION NOTE

2/13

1. Evolution of the SLIC protection

Over

the

years,

the

silicon

protection

performances have considerably changed.

The first generation of products like SMTHBTxx

and

SMTHDTxx

offered

fixed

overvoltage

protection against surges on either TIP or RING line

in four packages.

The following generation like THBTxx and

THDTxx still offered fixed overvoltage protection

against surges on both TIP and RING lines in two

packages.

The next step was the introduction of the LCP

devices which brought the advantage of full

programmable voltage.

Today, the CLP270M combines the features of all

the previous generations. In addition to that, it offers an overcurrent detection when operating in speech

mode and also a Failure Status output signal.

The figure 2 summarizes the firing modes of the CLP270M which basically holds the SLIC inside its correct

voltage and current values.

STMICROELECTRONICS CLP270M CONCEPT

Line card

operating

conditions

V

I

-I

+I

SWON

SWON

Programmable

thanks to an

external resistor

Programmable

thanks to any

external voltage

reference

Fig. 2: Line card protection

RINGS

-Vbat

-Vbat

Rp

Rsense

TIP

1

1

2

2

SLIC

(*)

(*) LCP1511D or THDT series or LCDP1511D

Ov v

ref

er oltage

erence

(+/- 270 V)

Overvoltage

detector

Overcurrent

detector

OR

Overvoltage

reference

(+/- 270 V)

Overvoltage

detector

Overcurrent

detector

OR

TIPL

TIPS

RINGL

FS

GND

SW3 SW1

SW4 SW2

Rsense

Rp

Ring

Generator

Fuse

Fuse

TIP

RING

External

voltage

reference

RING

I

Fig. 3 : CLP270M in line card