STLC3055N_09 STMICROELECTRONICS [STMicroelectronics], STLC3055N_09 Datasheet - Page 12

• Manufacturer Part Number: STLC3055N_09
• Description: WLL and ISDN-TA subscriber line interface circuit
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Functional description
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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 wire exchange their polarities following a
ramp transition (see
CREV. This capacitor is also setting the shape of the ringing trapezoidal waveform. When
the control pins set battery reversal the line polarity is reversed with a proper transition time
set via an external capacitor (CREV).
Figure 5.
Metering pulse injection (Ttx)
The metering pulses circuit consists of a burst shaping generator that gives a square wave
shaped and a low pass filter to reduce the harmonic distortion of the output signal.
The metering pulse is obtained starting from two logic signals:
●
●
These two signals are processed by a dedicated circuitry integrated on chip that generate
the metering pulse as an amplitude modulated shaped squarewave (SQTTX)
(see
Both the amplitude and the envelope of the squarewave (SQTTX) can be programmed by
means of external components. In particular the amplitude is set by the two resistors RLV
and the shaping by the capacitor CS.
D0
0
0
1
1
CKTTX: is a square wave at the TTX frequency (12 or 16 kHz) and should be
permanently applied to the CKTTX pin or at least for all the duration of the TTX pulse
(including rising and decay phases).
D0: enable the TTX generation circuit and define the TTX pulse duration.
Figure
6).
D1
SLIC states in active mode
TIP/RING typical transition from direct to reverse polarity
1
1
1
1
Figure
D2
0
1
0
1
5). The transition time is controlled by an external capacitor
GND
TIP
RING
dV/dT set
by CREV
4V typ.
Active TTX injection (reverse polarity)
Active TTX injection (normal polarity)
Active reverse polarity
Active normal polarity
Operating Mode
40V typ
ON-HOOK
STLC3055N