Hybrid Subscriber Line Interface Circuit (SLIC) Features Differential to single ended conversion No transformers required Minimum installation space Off-Hook detection and LED indicator drive Relay drive output Battery and ringing feed to line Logic interface:, OFHK, Mute of incoming audio Dial pulse detection oltage surge protection Applications Line Interface for: PABX Intercoms Key Systems Description ISSUE 5 April 995 Ordering Information 20 Pin SIL Package 0 C to 70 C The Zarlink Subscriber Line Interface Circuit provides a complete interface between the telephone line and a speech switch requiring only single bidirectional switch per crosspoint. The functions provided by the include bidirectional differential to single ended conversion in the speech path, line battery feed, ringing feed and loop and dial pulse detection. The device is fabricated as a thick film hybrid in a 20-pin single-inline package allowing optimum circuit board packing density. A A2 B C GND FEED Loop Feed/ Ring Feed Speech Circuit JUNCTOR A2 B CD OFHK RD RGND Relay Drive Circuit Loop Detection LED THRESH ADJ C2 Figure - Functional Block Diagram
A FEED IC C GND B LED OFHK THRESH ADJ A2 GND C2 JUNCTOR RD RGND CD 2 4 5 6 7 8 9 0 2 4 5 6 7 8 9 20 Pin Description Figure 2 - Pin Connections Pin # Name Description Tip Lead. Connects to the Tip lead (A-wire) of the telephone line. 2 A Positive Line Feed Supply oltage. Normally connected to A2. Ring Lead. Connects to the Ring lead (B-wire) of the telephone line. 4 FEED Negative Line Feed oltage and Ringing Input. Normally connected to Ring Relay. 5 IC Internal Connection. Leave open circuit. Use for testing only. 6 C Sense Input. Normally connected to negative line feed voltage supply. 7 GND Analog ground (0). Internally connected to pin. 8 B Negative Analog Supply oltage. 9 LED LED Drive Output. Drives an LED directly. Off-Hook condition, logic low. 0 OFHK Logic Low Output. Indicates closed loop condition (Off-Hook and dial pulsing). THRESH ADJ Allows adjustment of OFHK detection threshold. 2 A2 Positive Power Supply oltage. Normally connected to A. GND Analog Ground (0). Internally connected to pin 7. 4 C2 Loop Detector oltage Supply.Connected to negative line feed voltages supply. 5 Input mutes the incoming audio. Active low. 6 JUNCTOR Receive/transmit audio speech path. (referenced to 0 GND) 7 RD Relay Drive Output. Open collector sinks current when high. Diode clamp protected. 8 RGND Ground for Relay Drive Circuit. 9 Ring Control Input. Active high. 20 CD Clamping Diode. Normally connected to relay positive voltage. 2
Functional Description Speech Circuit The speech circuit converts the bidirectional and line pair to a bidirectional single ended junctor line. Figure illustrates a typical connection between two SLIC s through two crosspoint switches. This configuration gives optimum transhybrid loss as seen from Figure 4 given that the output impedance of the Junctor line is 604Ω. The input mutes signals coming from and to the junctor line while allowing the signal from the junctor to the tip-ring pair to be transmitted. Loop Detection The loop detection circuit determines whether a low enough impedances is across and to be recognized as an off-hook condition. (Threshold impedance = 5.4kΩ with no adjustment) This threshold level can be adjusted by the use of external resistors as shown in Figure 6. OFHK has low output drive capability so it may drive CMOS operating with different power supplies. Line Feed/Ring Feed Circuit The line feed circuit provides loop current and the ability to apply ringing onto and. The impedance from Ring Feed to GND is 600Ω which gives the loop current as: IL = oltage at FEED pin Telephone Impedance + 600 Amps The positive supply for the line feed circuit is A through the loop current is determined from FEED and GND. Relay Drive Circuit The relay drive circuit switches ringing onto FEED (Fig.7). The diode is present to suppress voltage transients during relay switches caused by the inductive coils of the relay. Ringing voltage includes AC ringing (90 typically) an ddc line feed voltage (-24 typically). JUNC 6 75Ω CROSSPOINT SWITCH JUNC 6 75Ω CROSSPOINT SWITCH Figure - SLIC Crosspoint Switch Connection
Absolute Maximum Ratings Parameter Symbol Min Max Units oltage Supplies - Ref to GND A, A2 B -8 +8 C, C2-5 2 Clamp Diode Breakdown oltage- Ref to RGND CD +5 Operating Temperature T AMB 0 +70 C 4 Storage Temperature T STG -40 +00 C 5 Power Dissipation P D.2 Watt Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied. AC Electrical Characteristics oltages are with respect to ground ( SS ), TA = 25 C, unless otherwise stated. Test conditions unless noted, A = A2 =+7, B =8, C2 =-24(+5%). Characteristics Sym Min Typ Max Units Test Conditions Junctor to differential output (tipring) gain. 2 Differential Input (tip-ring) to junctor gain On/Off Hook Detection Threshold Loop Resist Loop Current A JL 2.8 2.25 7 2.2 / db A LJ 0.0 0.2 0.2 / db R Thresh I Thresh 4.0.6 5.4 4.0 6.0 5. kω khz, 400m RMS source on pin 6. Note 2 khz, RMS Source on pins &. Note,2 Note. Note 4 Trans Hybrid Loss 55 db Notes,2. See Figure 2 5 Passband Linearity + db Notes,2 6 Power Supply Rejection Ratio (C to Junctor) 7 Common Mode Rejection Ratio (Tip and Ring to Junctor) 8 Low Frequency Cutoff (db) Junctor to Line Line to Junctor 9 High Frequency Cutoff (db) Line to Junctor Junctor to Line PSRR 40 db Notes,2 CMRR 40 db Notes,2 F LLJ 5 F LJL 20 F HLJ 800 F HJL 500 Hz Hz khz khz Notes,2 Notes,2 Notes,2 Notes,2 0 Longitudinal Balance 65 db Note Tip (or Ring) to ground AC input impedance Z I 00 Ω 2 Junctor output impedance Z OJ 604 Ω Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied. Typical figures are at 25 C with nominal+ 5 supplies and are for design aid only: not guaranteed and not subject to production testing. Note : 754Ω connected between JUNCTOR (pin 6) and O. Note 2: 604Ω connected between (pin ) and (pin ). 4
DC Electrical Characteristics. S U P Characteristics Sym Min Typ Max Units Test Conditions Operating Supply oltages 2 P Operating Supply Currents I A L Y High Level Input oltage 4 5 I N P U T S Low Level Input oltage High Level Input Current 6 Low Level input Current A, A2 B C, A2 - -0 I A2 I B I C I C2 IH IH 4.2 IL IL.8 I IH -28 I IH 700 I IL 00 I IL 7 Sink Current LED RD I LED I RD 2 65 6 00 OFHK, -6 CD==5,RGD=0 O RRD <.5 8 U T Diode Clamp Current I RLY 65 00 =RGND=0, CD=5 RRD <.5 9 P U High Level Output oltage OH 6 LED Unconnected 0 T Low Level Output oltage OL -6.5 LED Unconnected S OFHK High Level Output Current I OH 0 µa 2 Low Level Output Current I OL 0 µα Typical figures are at 25 C with nominal+ 5 supplies and are for design aid only: not guaranteed and not subject to production testing. -24 7 8 6.2. + -20 µa µa µa µa TRANSHYBRID LOSS (db) 0 20 0 40 50 60 550 600 650 700 750 800 850 900 950 LOAD IMPEDANCE ON JUNCTOR (Ω) Figure 4 - Return Loss S Junctor Load Impedance 5
O TR TR 604Ω 5 6 754Ω X 604Ω 0µF S 200Ω 0H 5 6 54Ω CAN BE MEASURED THAT TP =2X=2 TR (a) TRANSHYBRID LOSS = - 20LOG (O) (b) 2S Figure 5 - Transhybrid Loss Test Circuit R and R THRESH (kω) (a) GND R and R THRESH (kω) (a) C2 R R THRESH ADJ THRESH ADJ R (kω) (48 x R THRESH ) -28.8 R = R = 5.4 - R THRESH R (kω) (92 x R THRESH ) +604 R THRESH - 5.4 20 00 80 60 40 20 2000 000 2 4 5 6 R THRESH (kω) (a) 0 20 0 40 R THRESH (kω) (b) Figure 6 - Off-Hook Threshold Adjust 6
A LINE FEED/ FEED +90AC + FEED CLAMP DIODE CD RELAY COIL RD RELAY DRIE CIUIT RGND Figure 7 - Relay Drive Circuit 7
+7v +5 +5 CONTROL LOGIC A0 A A2 00 0 02 0 04 05 06 07 2 2 9 20 7 4 5 9 0 6 8 6 4 7 90AC ADDRESS OUT MD74SC7 OF 8 DECODER A0 A A2 00 0 02 0 04 05 06 07 5 MORE SLICS -8-24 0 +7 +5 +5 2 2 9 20 7 4 5 9 0 6 8 6 4 7 90AC A 0 -A 2 /D 0 -D L 0 MT882 Crosspoint Switch MD74SC7 OF 8 DECODER J 0 J J 2 J -L 7 5 MORE SLICS -8-24 0 +7 +5 +5 2 2 9 20 7 4 5 9 0 6 8 6 4 7 90AC A0 A A2 SELECT OUTPUT CMOS 452 8-INPUT MUX D 0 D D 2 D 7-8 -24 0 Figure 8 - PABX Typical Application 8
Side iew 0.080 Max (2.0 Max) 2.00 + 0.020 (50.8 + 0.5) 0.52+0.02 (.2+0.5) 2 4 9 20 0.00 + 0.002 (0.25 + 0.05) 0.2 Max (. Max) Notes: ) Not to scale 2) Dimensions in inches). ) (Dimensions in millimetres). *Dimensions to centre of pin & tolerance non accumulative. 0.05 + 0.0 (. + 0.5) 0.05 + 0.02 (. + 0.05) * * * 0.020 + 0.05 (0.5 + 0.) 0.00 + 0.0 (2.54 + 0.) 0.8 + 0.02 (4.6 + 0.5) Figure 9 -Mechanical Data 9
Notes: 0
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