SC88E43S 데이터 시트보기 (PDF) - Unspecified

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SC88E43S

EXTENDED VOLTAGE CALLING NUMBER IDENTIFICATION CIRCUIT 2

Unspecified 

Silan

Semiconductors

SC88E43

FUNCTIONAL DESCRIPTION

Detection of CLIP/CID Call Arrival Indicators

The cricuit in Figure 3 illustrates the relationship between the TRIGRC and TRIGout sig nals.Tpically,the three

pin combination is used to detect an event indicated by an increase of the TRIGin voltage from Vss to above the

Schmitt trigger high going threshold VT+ (see DC electrical characteristics).

Figure 3 shows a circuit to detect any one of three CLIP/CID call arrival indicators:line reversal,ring burst and

ringing.

Tip/A

C1=100nF R1=499kΩ V3

V1

R3=200kΩ

TRIGin

C2=100nF

Ring/B

R2=499kΩ V4

Notes:

The application circuit must ensure rhat, VTRIGin>max VT+

Where max VT+=3.74V @VDD=5.5V.

Tolerance to noise between A/B and VSS is:

max Vnoise=(min VT+)/0.30+0.7=5.6Vrms@4.5VVDD

Suggested R5C3 component values:

R5 from 10kΩ to 500kΩ; C3 from 47nF to 0.68µF

An example is C3=220nF, R5=150kΩ; TRIGout low from

21.6ms to 37.6ms after TRIGin Signal stops triggering the

circuit.

TRIGRC

TRIGout

To Microcontroller

SC88E43

VDD

max VT+=0.68 VDD

min VT+=0.48 VDD

To determine values for C3 and R5:

R5C3=-t/ln(1-VTRIGRC /VDD)

Figure 3 Circuit to Detect Line Reversal, Ring Burst and Ringing

1.Line Reversal Detection

Line reversal,or polarity reversal on the A and B wires indicates the arrival of an inconming CDScall,as soecified in

SIN227.When the event (line reversal) occurs,TRIGin rises past the high going Schmitt threshold VT+ and

TRIGout ,which is normally high,is pulled low going Schmitt threshold VT- and TRIGout returns high.The

components R5 and C3 (see Figure 3) at TRIGout low interval.

In a TE designed for CLIP,the TRIGout high to low transition may be used to interrupt or wake-up the micro-

controller.The controller can thus be put into power-down mode to conserve power in a battery operater TE.

2.Ring Buost Detection

CCA doesnot support the dual tone alert signal (refer to Dual Tone Alert single burst og ringing (duration 200-

450ms) that precedes CLIPFSK data.The ring burst may vary fron 30 to 75Vrms and is approximately 25Hz.

Again in aTEdesigned for CCA CLIP ,the TRIGout high to low reansition may be used to interrupt or wake-up the

microcontroller.The controller can thus be put into power-down mode to conserve powerin a battery operated TE.

HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD

Rev: 1.0 2000.12.31

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