STLC3075_09 datasheet(12/36 Pages) STMICROELECTRONICS

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Functional description

STLC3075

12/36

AC characteristics

The SLIC provides the standard SLIC transmission functions.

Once in active mode the SLIC can operate with two different Tx, Rx gains set by the gain set

control bit (See Table 7 below).

●

Input impedance synthesis: can be real or complex and is set by a scaled (x 50 or

x 25) external ZAC impedance

●

Transmit and receive: The AC signal present on the 2W port (TIP and RING pins) is

transferred to the Tx output with a -6 dB or -12 dB gain and from the Rx input to the 2W

port with a 0 dB or +6 dB gain

●

2 to 4 wires conversion: The balance impedance can be real or complex, the proper

cancellation is obtained by means of two external impedances ZA and ZB

Once in active mode (D1=1) the SLIC can operate in different states setting properly D0 and

D2 control bits (see also Table 8).

Polarity reversal

The D2 bit controls the line polarity, the transition between the two polarities is performed in

a ’soft’ way. This means that the TIP and RING wires exchange their polarities following a

ramp transition (see Figure 5). The transition time is controlled by an external capacitor

CREV. This capacitor also sets the shape of the ringing trapezoidal waveform. When the

control pins set the battery reversal, the line polarity is reversed with a proper transition time

set via an external capacitor (CREV).

Figure 5.

TIP/RING typical transition from direct to reverse polarity

Table 7.

Gain set in active mode

Gain set

4 to 2 wires gain

2 to 4 wires gain

Impedance synthesis scale factor

0 dB

-6 dB

x 50

+6 dB

-12 dB

x 25

Table 8.

SLIC states in active mode

Operating mode

Active normal polarity

Active reverse polarity

Active TTX injection (normal polarity.)

Active TTX injection (reverse polarity.)

GND

TIP

RING

dV/dT set

by CREV

4V typ.

40V typ

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