L3000N datasheet(13/32 Pages) STMICROELECTRONICS

13 / 32 page

It is possible to do it because :

When the CS = + 5V the output pins (ONHK,

GDK) are in high impedance condition (> 100K

Ω).

The signals present at the input pins are not

transfered into the SLIC.

When the CS = 0V the output pins change in

function of the values of the line current (Iline) and

the longitudinal current (IGDK). The operating

status of the SLIC are set by the voltage applied

to the input pins.

The rising edge of the CS signal latches the sig-

nal applied to the input pins. The status of the

SLIC will not change until the CS signal will be

again equal to zero.

See timings fig 7 & 8.

An additional input pin MR (Master Reset) can be

useful during the system start up phase or in

emergency condition.

In fact when this pin is set to ”0” the SLIC will be

set in POWER DOWN MODE. This pin has an in-

ternal pull-up resistor of about 200K

Ω

EXTERNAL COMPONENTS LIST

To set up the SLIC kit into operation, the following

parameters have to be defined :

- The DC feeding resistance RFS, defined as

the resistance of each side of the tradi-

tional feeding system (most common value

for RFS are 200, 400 or 500).

- The AC input/output SLIC impedance at line

terminals, ZML, to which the return loss

measurement is refered. It can be real

(typically 600

Ω) or complex.

- The equivalent AC impedance of the line

Zline used for evaluation of the trans-hy-

brid loss (2/4 wire conversion). It is usually

a complex impedance.

- The frequency of the ringing signal Fr (SLIC

can work with this frequency ranging from

16 to 68Hz).

- The value of the two resistors RP in series

with the line terminals ; main purpose of

the a.m. resistors is to allow primary pro-

tection to fire..

With these assumptions the following compo-

nents list is defined :

Figure 7: Typical Application Circuit

L3000N

L3000N - L3092

13/32

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