L3000N datasheet(6/32 Pages) STMICROELECTRONICS

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FUNCTIONAL DESCRIPTION

L3000N - HIGH VOLTAGE CIRCUIT

The L3000N line interface provides battery feed

for telephone lines and ringing injection. Both

these operations are done in Balance Mode. This

is very important in order to avoid the generation

of common mode signals in particular during the

pulse dialling operation of the telephone set con-

nected to the SLIC. The IC contains a state de-

coder that under external control can force the fol-

lowing

operational

modes

stand-by,

conversation and ringing.

In addition Power down mode can be forced con-

necting the bias current resistor to VDD or leaving

it open.

Two pins, IL and IT, carry out the information con-

cerning line status which is detected by sensing

the line current into the output stage.

The L3000N amplifies both the AC and DC signals

entering at pin 6 (VIN) by a factor equal to 40.

Separate grounds are provided :

- Analog ground as reference for analog sig-

nals

- Battery ground as a reference for the output

stages

The two ground should be shorted together at a

low impedance point.

L3092 - LOW VOLTAGE CIRCUIT

The L3092 Low Voltage Control Unit controls the

L3000N line interface module providing set up

data to set line feed characteristics and to inject

ringing. An on chip digital parallel interface allows

microprocessor

second

generation

COMBO as the TS5070 to control all the opera-

tions.

L3092 defines working states of Line Interface

Circuit and also informs the card controller about

line status.

L3000N WORKING STATES

In order to carry out the different possible opera-

tions, the L3000N has several different working

states. Each state is defined by the voltage re-

spectively applied by pin 12 and 13 of L3092 to

the pins 12 and 11 of L3000N.

Three different voltage levels (–3, 0, +3) are avail-

able at each connection, so defining nine possible

states as listed in tab. 1.

Appropriate combinations of two pins define four

of the five possible L3000N working states that

are:

a) Stand-by (SBY)

b) Conversation (CVS)

FUNCTIONAL DIAGRAM

L3000N

L3000N - L3092

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