STLC3065QTR 데이터 시트보기 (PDF) - STMicroelectronics

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STLC3065QTR

WLL SUBSCRIBER LINE INTERFACE CIRCUIT

STMicroelectronics 

STLC3065

Figure 5. Metering pulse generation circuit.

CTTX1

Low Pass Filter

C1

BURST

SHAPING CS

GENERATOR

RLV

SQTTX

RLV

D0

CKTTX

CTTX2

Square wave pulse metering

-

R1 R2 FTTX OP1

+

RTTX

CFL

C2

Sinusoidal wave

pulse metering

Required external components vs. filter order.

Order CFL R1 C! R2 C2 THD

1X

13%

2

X X X X 6%

3 X X X X X 3%

As already mentioned the metering pulse echo

cancellation is obtained by means of two external

components (RTTX and CTTX) that should match

the line impedance at the TTX frequency. This

simple network has a double effect:

Synthesise a low output impedance at the

TIP/RING pins at the TTX frequency.

Cut the eventual TTX echo that will be trans-

ferred from the line to the TX output.

Ringing

D0 D1 D2 P1 P2 DET DET1 DET2

1 0 0/1 1 1 RTrip disable disable

@fr

line 1+2

1 0 0/1 0 1 RTrip disable disable

@fr

line 2

1 0 0/1 1 0 RTrip disable disable

@fr

line 1

When this mode is selected STLC3065 self gen-

erate an higher negative battery (-70V typ.) in or-

der to allow a balanced ringing signal of typically

62Vpeak.

The SLIC core is set in ring mode via the control

inputs D0 and D1 set respectively to 0 and 1.

In this condition both the DC and AC feedback

loop are disabled and the SLIC core line drivers

operate as voltage buffers.

The ring waveform is obtained toggling the D2 con-

trol bit at the desired ring frequency. This bit in fact

controls the line polarity (0=direct; 1=reverse).

As in the ACTIVE mode the line voltage transition

is performed with a ramp transition, obtaining in

Figure 6. TIP/RING typical ringing waveform

GND

TIP

2.5V typ.

65V

typ.

dV/dT set

by CREV

RING

VBAT

2.5V typ.

this way a trapezoidal balanced ring waveform

(see fig.6).

The shaping is defined by the CREV external

capacitor.

Selecting the proper capacitor value it is possible

to get different crest fattor values. The following

table shows the crest factor values obtained with

a 20Hz and 25Hz ring frequency and with 1REN.

This value are valid either with European or USA

specification:

CREV

22nF

27nF

33nF

CREST

FACTOR

@20Hz

1.2

1.25

1.33

CREST

FACTOR

@25Hz

1.26

1.32

Not significant (*)

(*)Distorsion already less than 10%.

10/27

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