June 2011

Doc ID 10917 Rev 2

1/15

AN2053

Application note

SLIC protection for both classical and new networks

Introduction

Even with booming digital technologies, telecom analog lines remain the most used link in

the world. The market opening to new operators, reserved so far to national telecom

administration, makes an increase of new applications using this simple and cheap way to

supply speech information. POTS (plain old telephone set) is still alive.

Figure 1.

Proposed solutions for the subscriber

Figure 1 shows possibilities subscribers already have got and which will be in a growing

phase in the near future. This will split the SLIC (Subscriber Line Interface Circuit) in two

different types according to the application:

In the second case shown at the bottom of Figure 1, the long distance carrying of the signal

is assumed by modern digital supports like optical fibers, coax, RF link etc.

For both of these applications the protection needs remain one of the major issues of the

system design, so STMicroelectronics, which is one of the major players in the world of

telecom protection, already proposes optimized solutions for these two topologies.

Suscriber house

High speed digital link

Long line

Short line

Pots

Pots

Central office

High speed to

Pots coupling

www.st.com